From 4adbd0c075c6abb6df66908554868329956c98c3 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Tue, 23 Sep 2025 10:50:54 -0700
Subject: [PATCH 01/24] Feature: Adding initial intergration of join as a
 system call

---
 Makefile         |  1 +
 kernel/syscall.c |  2 ++
 kernel/syscall.h |  1 +
 user/join.c      | 32 ++++++++++++++++++++++++++++++++
 user/user.h      |  1 +
 user/usys.pl     |  1 +
 6 files changed, 38 insertions(+)
 create mode 100644 user/join.c

diff --git a/Makefile b/Makefile
index cf031b0..34a9540 100644
--- a/Makefile
+++ b/Makefile
@@ -142,6 +142,7 @@ UPROGS=\
 	$U/_logstress\
 	$U/_forphan\
 	$U/_dorphan\
+	$U/_join\
 
 fs.img: mkfs/mkfs README.md $(UPROGS)
 	mkfs/mkfs fs.img README.md $(UPROGS)
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 076d965..4c431a6 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -101,6 +101,7 @@ extern uint64 sys_unlink(void);
 extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
+extern uint64 sys_join(void);
 
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
@@ -126,6 +127,7 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
+[SYS_join]    sys_join,
 };
 
 void
diff --git a/kernel/syscall.h b/kernel/syscall.h
index 3dd926d..79645b7 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -20,3 +20,4 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+#define SYS_join   22
diff --git a/user/join.c b/user/join.c
new file mode 100644
index 0000000..0dbb4ff
--- /dev/null
+++ b/user/join.c
@@ -0,0 +1,32 @@
+#include "kernel/types.h"
+#include "user/user.h"
+
+int main(int argc, char *argv[]){
+    // ensure correct usage of command line args
+    if (argc != 3){
+        printf("Usage: join file1.txt file2.txt\n");
+        exit(1);
+    }
+
+    printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
+
+
+    // initiate data structure for file content
+    // set two arrays of 50 lines and 256 chars each
+    char file1_lines[50][256];
+    char file2_lines[50][256];
+
+
+    // read both files
+    printf("Reading first file...");
+    int count1 = read_file_lines(argv[1], file1_lines, 50);
+
+    printf("Reading second file...");
+    int count2 = read_file_lines(argv[2], file2_lines, 50);
+    
+    // join both files
+    printf("joining both files");
+    join_files(file1_lines, count1, file2_lines, count2);
+
+    exit(0);
+}
diff --git a/user/user.h b/user/user.h
index ac84de9..5dcac5a 100644
--- a/user/user.h
+++ b/user/user.h
@@ -24,6 +24,7 @@ int getpid(void);
 char* sys_sbrk(int,int);
 int pause(int);
 int uptime(void);
+void join(void);
 
 // ulib.c
 int stat(const char*, struct stat*);
diff --git a/user/usys.pl b/user/usys.pl
index c5d4c3a..58f406f 100755
--- a/user/usys.pl
+++ b/user/usys.pl
@@ -42,3 +42,4 @@ sub entry {
 entry("sbrk");
 entry("pause");
 entry("uptime");
+entry("join");

From 0fc2d869d97310c82b0dcf984448e11e49df4c15 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Tue, 23 Sep 2025 11:31:11 -0700
Subject: [PATCH 02/24] Feature: Adding methods to join syscall

---
 kernel/sysproc.c | 163 +++++++++++++++++++++++++++++++++++++++++++++++
 user/join.c      |   6 +-
 2 files changed, 166 insertions(+), 3 deletions(-)

diff --git a/kernel/sysproc.c b/kernel/sysproc.c
index 3044d00..2dc74c7 100644
--- a/kernel/sysproc.c
+++ b/kernel/sysproc.c
@@ -105,3 +105,166 @@ sys_uptime(void)
   release(&tickslock);
   return xticks;
 }
+
+void
+sys_join(void)
+{
+    // // Hector's functions
+    // void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2);
+    // void print_joined_line(char* field, char* rest1, char* rest2);
+    // char* get_rest_of_line(char* line);
+    // 
+    // 
+    // // Demetrius's functions
+    // char* get_first_field(char* line);
+    // int read_file_lines(char* filename, char lines[][256], int count2);
+    
+    /**
+     * Extracts the first field (word) from a line
+     * Returns a pointer to the first field, or NULL if line is empty
+     */
+    char* get_first_field(char* line) {
+        if (line == NULL || *line == '\0') {
+            return NULL;
+        }
+        
+        // Skip leading whitespace
+        while (*line == ' ' || *line == '\t') {
+            line++;
+        }
+        
+        // If line is empty after skipping whitespace
+        if (*line == '\0') {
+            return NULL;
+        }
+        
+        return line;
+    }
+
+    /**
+     * Function to get the rest of the line so it is everything 
+     * after the first word 
+    */
+    char* get_rest_of_line(char* line){
+
+        // return empty if line is not valid
+        if(line == NULL || *line == '\0'){
+            return "";
+        }
+
+        char* ptr = line;
+        // skip leading whitespace
+        while(*ptr ==  ' ' || *ptr == '\t'){
+            ptr++;
+        }
+        // skip first field until reached whitespace or end of line
+        while (*ptr != '\0' && *ptr != ' ' && *ptr != '\t' ){
+            ptr++;
+        }
+        // skip whitespace between first field and rest
+        while(*ptr == ' ' || *ptr == '\t'){
+            ptr++;
+        }
+        return ptr;
+    }
+
+    /**
+     * Reads lines from a file into the provided array
+     * Returns the number of lines successfully read
+     */
+    int read_file_lines(char* filename, char lines[][256], int max_count) {
+        int fd = open(filename, 0); // 0 = O_RDONLY
+        if (fd < 0) {
+            printf("Error: Cannot open file '%s'\n", filename);
+            return 0;
+        }
+        
+        int line_count = 0;
+        char buffer[256];
+        int pos = 0;
+        char c;
+        
+        while (line_count < max_count && read(fd, &c, 1) > 0) {
+            if (c == '\n') {
+                // End of line found
+                buffer[pos] = '\0';
+                
+                // Copy the line to the array
+                int i = 0;
+                while (i < 255 && buffer[i] != '\0') {
+                    lines[line_count][i] = buffer[i];
+                    i++;
+                }
+                lines[line_count][i] = '\0';
+                
+                line_count++;
+                pos = 0; // Reset position for next line
+            } else if (pos < 255) {
+                // Add character to buffer
+                buffer[pos] = c;
+                pos++;
+            }
+        }
+        
+        // Handle the last line if file doesn't end with newline
+        if (pos > 0 && line_count < max_count) {
+            buffer[pos] = '\0';
+            int i = 0;
+            while (i < 255 && buffer[i] != '\0') {
+                lines[line_count][i] = buffer[i];
+                i++;
+            }
+            lines[line_count][i] = '\0';
+            line_count++;
+        }
+        
+        close(fd);
+        return line_count;
+    }
+    /**
+     * function prints joined line 
+     * "first word" "rest line file 1" "rest line file 2"
+    */
+    void print_joined_line(char* field, char* rest1, char* rest2){
+        printf("%s %s %s\n", field, rest1, rest2);
+    }
+
+    /**
+     * Compares lines from both files and looks for matches in the 
+     * first field
+     * If the fields match then print joined line
+    */
+    void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2){
+
+        // iterate through each line from file 1 
+        for (int i =0; i< count1; i++){
+            char* field1 = get_first_field(field1_lines[i]); // reads full line but only gets first word to check for match
+            // skip is field is empty 
+            if(field1 == 0){
+                continue;
+            }
+
+
+            // iterate through lines in file two 
+            for (int j =0; j < count2; j++){
+                char* field2 = get_first_field(field2_lines[j]); // read full line but only gets first word
+                // skip if field is empty
+                if(field2 == 0){
+                    continue;
+                }
+
+                // check if both words are equal returns 0 if true
+                if(strcmp(field1, field2) == 0){
+                    // get rest of lines for both files from where we got field
+                    char* rest1 = get_rest_of_line(file1_lines[i]);
+                    char* rest2 = get_rest_of_line(file2_lines[j]);
+
+                    print_joined_line(field1, rest1, rest2);
+
+
+                }
+            }
+        }
+        printf("join_files() completed");
+    }
+}
diff --git a/user/join.c b/user/join.c
index 0dbb4ff..9709db8 100644
--- a/user/join.c
+++ b/user/join.c
@@ -19,14 +19,14 @@ int main(int argc, char *argv[]){
 
     // read both files
     printf("Reading first file...");
-    int count1 = read_file_lines(argv[1], file1_lines, 50);
+    int count1 = join.read_file_lines(argv[1], file1_lines, 50);
 
     printf("Reading second file...");
-    int count2 = read_file_lines(argv[2], file2_lines, 50);
+    int count2 = join.read_file_lines(argv[2], file2_lines, 50);
     
     // join both files
     printf("joining both files");
-    join_files(file1_lines, count1, file2_lines, count2);
+    join.join_files(file1_lines, count1, file2_lines, count2);
 
     exit(0);
 }

From 12bce47b7a4dfb451412006ea813f4921f89c47b Mon Sep 17 00:00:00 2001
From: HECTOR NUNEZ <hnunez2@dons.usfca.edu>
Date: Tue, 23 Sep 2025 18:16:52 -0700
Subject: [PATCH 03/24] bug fixes to join implementation, added to user dir
 only

---
 kernel/syscall.c |   3 +-
 kernel/syscall.h |   1 -
 kernel/sysproc.c | 162 -------------------------------
 user/join.c      | 248 ++++++++++++++++++++++++++++++++++++++++++++---
 user/user.h      |   1 -
 user/usys.pl     |   1 -
 6 files changed, 238 insertions(+), 178 deletions(-)

diff --git a/kernel/syscall.c b/kernel/syscall.c
index 4c431a6..6dc5deb 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -101,7 +101,7 @@ extern uint64 sys_unlink(void);
 extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
-extern uint64 sys_join(void);
+
 
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
@@ -127,7 +127,6 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
-[SYS_join]    sys_join,
 };
 
 void
diff --git a/kernel/syscall.h b/kernel/syscall.h
index 79645b7..3dd926d 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -20,4 +20,3 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
-#define SYS_join   22
diff --git a/kernel/sysproc.c b/kernel/sysproc.c
index 2dc74c7..6cc0bc6 100644
--- a/kernel/sysproc.c
+++ b/kernel/sysproc.c
@@ -106,165 +106,3 @@ sys_uptime(void)
   return xticks;
 }
 
-void
-sys_join(void)
-{
-    // // Hector's functions
-    // void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2);
-    // void print_joined_line(char* field, char* rest1, char* rest2);
-    // char* get_rest_of_line(char* line);
-    // 
-    // 
-    // // Demetrius's functions
-    // char* get_first_field(char* line);
-    // int read_file_lines(char* filename, char lines[][256], int count2);
-    
-    /**
-     * Extracts the first field (word) from a line
-     * Returns a pointer to the first field, or NULL if line is empty
-     */
-    char* get_first_field(char* line) {
-        if (line == NULL || *line == '\0') {
-            return NULL;
-        }
-        
-        // Skip leading whitespace
-        while (*line == ' ' || *line == '\t') {
-            line++;
-        }
-        
-        // If line is empty after skipping whitespace
-        if (*line == '\0') {
-            return NULL;
-        }
-        
-        return line;
-    }
-
-    /**
-     * Function to get the rest of the line so it is everything 
-     * after the first word 
-    */
-    char* get_rest_of_line(char* line){
-
-        // return empty if line is not valid
-        if(line == NULL || *line == '\0'){
-            return "";
-        }
-
-        char* ptr = line;
-        // skip leading whitespace
-        while(*ptr ==  ' ' || *ptr == '\t'){
-            ptr++;
-        }
-        // skip first field until reached whitespace or end of line
-        while (*ptr != '\0' && *ptr != ' ' && *ptr != '\t' ){
-            ptr++;
-        }
-        // skip whitespace between first field and rest
-        while(*ptr == ' ' || *ptr == '\t'){
-            ptr++;
-        }
-        return ptr;
-    }
-
-    /**
-     * Reads lines from a file into the provided array
-     * Returns the number of lines successfully read
-     */
-    int read_file_lines(char* filename, char lines[][256], int max_count) {
-        int fd = open(filename, 0); // 0 = O_RDONLY
-        if (fd < 0) {
-            printf("Error: Cannot open file '%s'\n", filename);
-            return 0;
-        }
-        
-        int line_count = 0;
-        char buffer[256];
-        int pos = 0;
-        char c;
-        
-        while (line_count < max_count && read(fd, &c, 1) > 0) {
-            if (c == '\n') {
-                // End of line found
-                buffer[pos] = '\0';
-                
-                // Copy the line to the array
-                int i = 0;
-                while (i < 255 && buffer[i] != '\0') {
-                    lines[line_count][i] = buffer[i];
-                    i++;
-                }
-                lines[line_count][i] = '\0';
-                
-                line_count++;
-                pos = 0; // Reset position for next line
-            } else if (pos < 255) {
-                // Add character to buffer
-                buffer[pos] = c;
-                pos++;
-            }
-        }
-        
-        // Handle the last line if file doesn't end with newline
-        if (pos > 0 && line_count < max_count) {
-            buffer[pos] = '\0';
-            int i = 0;
-            while (i < 255 && buffer[i] != '\0') {
-                lines[line_count][i] = buffer[i];
-                i++;
-            }
-            lines[line_count][i] = '\0';
-            line_count++;
-        }
-        
-        close(fd);
-        return line_count;
-    }
-    /**
-     * function prints joined line 
-     * "first word" "rest line file 1" "rest line file 2"
-    */
-    void print_joined_line(char* field, char* rest1, char* rest2){
-        printf("%s %s %s\n", field, rest1, rest2);
-    }
-
-    /**
-     * Compares lines from both files and looks for matches in the 
-     * first field
-     * If the fields match then print joined line
-    */
-    void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2){
-
-        // iterate through each line from file 1 
-        for (int i =0; i< count1; i++){
-            char* field1 = get_first_field(field1_lines[i]); // reads full line but only gets first word to check for match
-            // skip is field is empty 
-            if(field1 == 0){
-                continue;
-            }
-
-
-            // iterate through lines in file two 
-            for (int j =0; j < count2; j++){
-                char* field2 = get_first_field(field2_lines[j]); // read full line but only gets first word
-                // skip if field is empty
-                if(field2 == 0){
-                    continue;
-                }
-
-                // check if both words are equal returns 0 if true
-                if(strcmp(field1, field2) == 0){
-                    // get rest of lines for both files from where we got field
-                    char* rest1 = get_rest_of_line(file1_lines[i]);
-                    char* rest2 = get_rest_of_line(file2_lines[j]);
-
-                    print_joined_line(field1, rest1, rest2);
-
-
-                }
-            }
-        }
-        printf("join_files() completed");
-    }
-}
diff --git a/user/join.c b/user/join.c
index 9709db8..847d3e6 100644
--- a/user/join.c
+++ b/user/join.c
@@ -1,32 +1,258 @@
 #include "kernel/types.h"
 #include "user/user.h"
+#include "kernel/stat.h"
+
+
+    // // Hector's functions
+     //void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2);
+     //void print_joined_line(char* field, char* rest1, char* rest2);
+     //char* get_rest_of_line(char* line);
+    // 
+    // 
+    // // Demetrius's functions
+     //char* get_first_field(char* line);
+    // int read_file_lines(char* filename, char lines[][256], int count2);
+
+     // helper functions 
+    //compare_strings(char* str1, char* str2)
+    //terminate_first_field(char* line)
+    /**
+     * String comparison iterates through each char in both
+     * strings to see if they match if non return non-zero
+     */
+
+    static char file1_lines[50][256];
+    static char file2_lines[50][256];
+
+    int compare_strings(char* str1, char* str2){
+    	while (*str1 && *str2){
+    		if (*str1 != *str2){
+    			return *str1 - *str2;
+    		}
+    		str1++;
+    		str2++;
+    	}
+    	return *str1 - *str2;
+    }
+
+     /**
+     * Extracts the first field (word) from a line
+     * Returns a pointer to the first field, or NULL if line is empty
+     */
+
+    char* get_first_field(char* line) {
+        if (line == 0 || *line == '\0') {
+            return 0;
+        }
+        
+        // Skip leading whitespace
+        while (*line == ' ' || *line == '\t') {
+            line++;
+        }
+        
+        // If line is empty after skipping whitespace
+        if (*line == '\0') {
+            return 0;
+        }
+        
+        return line;
+    }
+
+    /**
+     * Function to get the rest of the line so it is everything 
+     * after the first word 
+    */
+    char* get_rest_of_line(char* line){
+
+        // return empty if line is not valid
+        if(line == 0 || *line == '\0'){
+            return "";
+        }
+
+        char* ptr = line;
+        // skip leading whitespace
+        while(*ptr ==  ' ' || *ptr == '\t'){
+            ptr++;
+        }
+        // skip first field until reached whitespace or end of line
+        while (*ptr != '\0' && *ptr != ' ' && *ptr != '\t' ){
+            ptr++;
+        }
+        // skip whitespace between first field and rest
+        while(*ptr == ' ' || *ptr == '\t'){
+            ptr++;
+        }
+        return ptr;
+    }
+
+    void terminate_first_field(char* line){
+    	char* ptr = line;
+
+		// skip whitespace
+    	while (*ptr == ' ' || *ptr == '\t'){
+    		ptr++;
+    	}
+
+    	// get the end of the first word
+    	while (*ptr != '\0' && *ptr != ' ' && *ptr != '\n' && *ptr != '\t'){
+    		ptr++;
+    	}
+    	// terminate first word
+    	if(*ptr != '\0'){
+    		*ptr = '\0';
+    	}
+    }
+
+    /**
+     * Reads lines from a file into the provided array
+     * Returns the number of lines successfully read
+     */
+    int read_file_lines(char* filename, char lines[][256], int max_count) {
+        int fd = open(filename, 0); // 0 = O_RDONLY
+        if (fd < 0) {
+            printf("Error: Cannot open file '%s'\n", filename);
+            return 0;
+        }
+        
+        int line_count = 0;
+        char buffer[256];
+        int pos = 0;
+        char c;
+        
+        while (line_count < max_count && read(fd, &c, 1) > 0) {
+            if (c == '\n') {
+                // End of line found
+                buffer[pos] = '\0';
+                
+                // Copy the line to the array
+                int i = 0;
+                while (i < 255 && buffer[i] != '\0') {
+                    lines[line_count][i] = buffer[i];
+                    i++;
+                }
+                lines[line_count][i] = '\0';
+                
+                line_count++;
+                pos = 0; // Reset position for next line
+            } else if (pos < 255) {
+                // Add character to buffer
+                buffer[pos] = c;
+                pos++;
+            }
+        }
+     
+        // Handle the last line if file doesn't end with newline
+        if (pos > 0 && line_count < max_count) {
+            buffer[pos] = '\0';
+            int i = 0;
+            while (i < 255 && buffer[i] != '\0') {
+                lines[line_count][i] = buffer[i];
+                i++;
+            }
+            lines[line_count][i] = '\0';
+            line_count++;
+        }
+        
+        close(fd);
+        return line_count;
+    }
+
+    /**
+         * function prints joined line 
+         * "first word" "rest line file 1" "rest line file 2"
+        */
+        void print_joined_line(char* field, char* rest1, char* rest2){
+            printf("%s %s %s\n", field, rest1, rest2);
+        }
+    
+        /**
+         * Compares lines from both files and looks for matches in the 
+         * first field
+         * If the fields match then print joined line
+        */
+        void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2){
+    
+            // iterate through each line from file 1 
+            for (int i =0; i< count1; i++){
+            	char line1_copy[256]; // make copy to avoid messing with original
+            	int k = 0;
+            	while (k<255 && file1_lines[i][k] != '\0'){
+            		line1_copy[k] = file1_lines[i][k];
+            		k++;
+            	}
+            	line1_copy[k] = '\0';
+            	
+                char* field1 = get_first_field(line1_copy); // reads full line but only gets first word to check for match
+                // skip is field is empty 
+                if(field1 == 0){
+                    continue;
+                }
+
+                terminate_first_field(field1); // get rid of first word to make comparing easier
+    
+            // iterate through lines in file two 
+            for (int j =0; j < count2; j++){
+            	char line2_copy[256]; // make copy to avoid messing with original
+            	            	int m = 0;
+            	            	while (m<255 && file2_lines[j][m] != '\0'){
+            	            		line2_copy[m] = file2_lines[j][m];
+            	            		m++;
+            	            	}
+            	            	line2_copy[m] = '\0';
+            	            
+                char* field2 = get_first_field(line2_copy); // read full line but only gets first word
+                // skip if field is empty
+                if(field2 == 0){
+                    continue;
+                }
+                terminate_first_field(field2);
+
+                // check if both words are equal returns 0 if true
+                if(compare_strings(field1, field2) == 0){
+                    // get rest of lines for both files from where we got field
+                    char* rest1 = get_rest_of_line(file1_lines[i]);
+                    char* rest2 = get_rest_of_line(file2_lines[j]);
+
+                    print_joined_line(field1, rest1, rest2);
+
+
+                }
+            }
+    }
+}
 
 int main(int argc, char *argv[]){
     // ensure correct usage of command line args
+    printf("DEBUG: starting join...\n");
     if (argc != 3){
         printf("Usage: join file1.txt file2.txt\n");
         exit(1);
     }
+    printf("DEBUG: Args okay, reading files\n");
 
     printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
 
 
-    // initiate data structure for file content
-    // set two arrays of 50 lines and 256 chars each
-    char file1_lines[50][256];
-    char file2_lines[50][256];
-
-
     // read both files
     printf("Reading first file...");
-    int count1 = join.read_file_lines(argv[1], file1_lines, 50);
+    int count1 = read_file_lines(argv[1], file1_lines, 50);
+    printf("Read %d lines from file1\n", count1);
+    if(count1 == 0){
+    	printf("ERROR: failed to read lines from %s\n", argv[1]);
+    	exit(1);
+    }
 
     printf("Reading second file...");
-    int count2 = join.read_file_lines(argv[2], file2_lines, 50);
-    
+    int count2 = read_file_lines(argv[2], file2_lines, 50);
+    printf("Read %d lines from file2\n", count2);
+        if(count2 == 0){
+    	printf("ERROR: failed to read lines from %s\n", argv[2]);
+    	exit(1);
+    }
     // join both files
-    printf("joining both files");
-    join.join_files(file1_lines, count1, file2_lines, count2);
+    printf("joining both files\n");
+    join_files(file1_lines, count1, file2_lines, count2);
+    printf("join completed\n");
 
     exit(0);
 }
diff --git a/user/user.h b/user/user.h
index 5dcac5a..ac84de9 100644
--- a/user/user.h
+++ b/user/user.h
@@ -24,7 +24,6 @@ int getpid(void);
 char* sys_sbrk(int,int);
 int pause(int);
 int uptime(void);
-void join(void);
 
 // ulib.c
 int stat(const char*, struct stat*);
diff --git a/user/usys.pl b/user/usys.pl
index 58f406f..c5d4c3a 100755
--- a/user/usys.pl
+++ b/user/usys.pl
@@ -42,4 +42,3 @@ sub entry {
 entry("sbrk");
 entry("pause");
 entry("uptime");
-entry("join");

From a0b3e9fa6c6b7e4ce3138d762f184f2a7e46f2db Mon Sep 17 00:00:00 2001
From: HECTOR NUNEZ <hnunez2@dons.usfca.edu>
Date: Tue, 23 Sep 2025 18:32:23 -0700
Subject: [PATCH 04/24] updating join, adding it to user dir only

---
 user/join.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/user/join.c b/user/join.c
index 847d3e6..86dd19d 100644
--- a/user/join.c
+++ b/user/join.c
@@ -171,6 +171,7 @@
          * If the fields match then print joined line
         */
         void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2){
+        	int matches_found = 0;
     
             // iterate through each line from file 1 
             for (int i =0; i< count1; i++){
@@ -209,6 +210,8 @@
 
                 // check if both words are equal returns 0 if true
                 if(compare_strings(field1, field2) == 0){
+                	matches_found++;
+                
                     // get rest of lines for both files from where we got field
                     char* rest1 = get_rest_of_line(file1_lines[i]);
                     char* rest2 = get_rest_of_line(file2_lines[j]);
@@ -218,17 +221,19 @@
 
                 }
             }
+            
+    }
+    if(matches_found == 0){
+    	printf("No matches found\n");
     }
 }
 
 int main(int argc, char *argv[]){
     // ensure correct usage of command line args
-    printf("DEBUG: starting join...\n");
     if (argc != 3){
         printf("Usage: join file1.txt file2.txt\n");
         exit(1);
     }
-    printf("DEBUG: Args okay, reading files\n");
 
     printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
 

From 1cd9c45502e786dc635308823b8116b2857bd500 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 24 Sep 2025 13:25:05 -0700
Subject: [PATCH 05/24] cleaned up indentation in join_files and added writing
 to txt file for the joined file

---
 user/join.c | 118 ++++++++++++++++++++++++++++++----------------------
 1 file changed, 68 insertions(+), 50 deletions(-)

diff --git a/user/join.c b/user/join.c
index 86dd19d..533ec0d 100644
--- a/user/join.c
+++ b/user/join.c
@@ -1,11 +1,12 @@
 #include "kernel/types.h"
 #include "user/user.h"
 #include "kernel/stat.h"
+#include "kernel/fcntl.h"
 
 
     // // Hector's functions
-     //void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2);
-     //void print_joined_line(char* field, char* rest1, char* rest2);
+     //void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file));
+     //void print_joined_line(int output_file, char* field, char* rest1, char* rest2);
      //char* get_rest_of_line(char* line);
     // 
     // 
@@ -16,6 +17,7 @@
      // helper functions 
     //compare_strings(char* str1, char* str2)
     //terminate_first_field(char* line)
+    
     /**
      * String comparison iterates through each char in both
      * strings to see if they match if non return non-zero
@@ -108,8 +110,8 @@
      * Returns the number of lines successfully read
      */
     int read_file_lines(char* filename, char lines[][256], int max_count) {
-        int fd = open(filename, 0); // 0 = O_RDONLY
-        if (fd < 0) {
+        int file = open(filename, 0); // 0 = O_RDONLY
+        if (file < 0) {
             printf("Error: Cannot open file '%s'\n", filename);
             return 0;
         }
@@ -119,7 +121,7 @@
         int pos = 0;
         char c;
         
-        while (line_count < max_count && read(fd, &c, 1) > 0) {
+        while (line_count < max_count && read(file, &c, 1) > 0) {
             if (c == '\n') {
                 // End of line found
                 buffer[pos] = '\0';
@@ -153,7 +155,7 @@
             line_count++;
         }
         
-        close(fd);
+        close(file);
         return line_count;
     }
 
@@ -161,46 +163,61 @@
          * function prints joined line 
          * "first word" "rest line file 1" "rest line file 2"
         */
-        void print_joined_line(char* field, char* rest1, char* rest2){
+        void print_joined_line(int output_file, char* field, char* rest1, char* rest2){
             printf("%s %s %s\n", field, rest1, rest2);
+
+            // Write to the file
+            write(output_file, field, strlen(field));
+            write(output_file, " ", 1);
+            write(output_file, rest1, strlen(rest1));
+            write(output_file, " ", 1);
+            write(output_file, rest2, strlen(rest2));
+            write(output_file, "\n", 1);
         }
     
-        /**
-         * Compares lines from both files and looks for matches in the 
-         * first field
-         * If the fields match then print joined line
-        */
-        void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2){
-        	int matches_found = 0;
-    
-            // iterate through each line from file 1 
-            for (int i =0; i< count1; i++){
-            	char line1_copy[256]; // make copy to avoid messing with original
-            	int k = 0;
-            	while (k<255 && file1_lines[i][k] != '\0'){
-            		line1_copy[k] = file1_lines[i][k];
-            		k++;
-            	}
-            	line1_copy[k] = '\0';
-            	
-                char* field1 = get_first_field(line1_copy); // reads full line but only gets first word to check for match
-                // skip is field is empty 
-                if(field1 == 0){
-                    continue;
-                }
+    /**
+     * Compares lines from both files and looks for matches in the 
+     * first field
+     * If the fields match then print joined line
+    */
+    void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file){
+        int matches_found = 0;
+
+        // Open the output file for writing (create it if it doesn't exist)
+        int output_fd = open(output_file, O_CREATE | O_RDWR);
+        if (output_fd < 0) {
+            printf("Error: Cannot open output file '%s'\n", output_file);
+            return;
+        }
+
+        // iterate through each line from file 1 
+        for (int i =0; i< count1; i++){
+            char line1_copy[256]; // make copy to avoid messing with original
+            int k = 0;
+            while (k<255 && file1_lines[i][k] != '\0'){
+                line1_copy[k] = file1_lines[i][k];
+                k++;
+            }
+            line1_copy[k] = '\0';
+            
+            char* field1 = get_first_field(line1_copy); // reads full line but only gets first word to check for match
+            // skip is field is empty 
+            if(field1 == 0){
+                continue;
+            }
+
+            terminate_first_field(field1); // get rid of first word to make comparing easier
 
-                terminate_first_field(field1); // get rid of first word to make comparing easier
-    
             // iterate through lines in file two 
             for (int j =0; j < count2; j++){
-            	char line2_copy[256]; // make copy to avoid messing with original
-            	            	int m = 0;
-            	            	while (m<255 && file2_lines[j][m] != '\0'){
-            	            		line2_copy[m] = file2_lines[j][m];
-            	            		m++;
-            	            	}
-            	            	line2_copy[m] = '\0';
-            	            
+                char line2_copy[256]; // make copy to avoid messing with original
+                int m = 0;
+                while (m<255 && file2_lines[j][m] != '\0'){
+                    line2_copy[m] = file2_lines[j][m];
+                    m++;
+                }
+                line2_copy[m] = '\0';
+                            
                 char* field2 = get_first_field(line2_copy); // read full line but only gets first word
                 // skip if field is empty
                 if(field2 == 0){
@@ -210,23 +227,23 @@
 
                 // check if both words are equal returns 0 if true
                 if(compare_strings(field1, field2) == 0){
-                	matches_found++;
+                    matches_found++;
                 
                     // get rest of lines for both files from where we got field
                     char* rest1 = get_rest_of_line(file1_lines[i]);
                     char* rest2 = get_rest_of_line(file2_lines[j]);
 
-                    print_joined_line(field1, rest1, rest2);
-
+                    print_joined_line(output_fd, field1, rest1, rest2);
 
                 }
-            }
-            
-    }
-    if(matches_found == 0){
-    	printf("No matches found\n");
+            }                
+        }
+        if(matches_found == 0){
+            printf("No matches found\n");
+        }
+        // Close the output file
+        close(output_fd);
     }
-}
 
 int main(int argc, char *argv[]){
     // ensure correct usage of command line args
@@ -256,7 +273,8 @@ int main(int argc, char *argv[]){
     }
     // join both files
     printf("joining both files\n");
-    join_files(file1_lines, count1, file2_lines, count2);
+    join_files(file1_lines, count1, file2_lines, count2, "joined.txt");
+    printf("saving in a new file called joined.txt\n");
     printf("join completed\n");
 
     exit(0);

From 274d6faf532cc07529dbc2a8b38c0a01903e14d3 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 24 Sep 2025 13:30:34 -0700
Subject: [PATCH 06/24] added txt files to be tested

---
 Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 34a9540..88f3211 100644
--- a/Makefile
+++ b/Makefile
@@ -144,8 +144,8 @@ UPROGS=\
 	$U/_dorphan\
 	$U/_join\
 
-fs.img: mkfs/mkfs README.md $(UPROGS)
-	mkfs/mkfs fs.img README.md $(UPROGS)
+fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt
+	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt
 
 -include kernel/*.d user/*.d
 

From 37af92b4ee560dd1da82df6d24200373534c3f37 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 24 Sep 2025 13:36:42 -0700
Subject: [PATCH 07/24] added 2 test txts with 25 lines each of ~40 chars per
 line

---
 file1.txt | 25 +++++++++++++++++++++++++
 file2.txt | 25 +++++++++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 file1.txt
 create mode 100644 file2.txt

diff --git a/file1.txt b/file1.txt
new file mode 100644
index 0000000..2cd7416
--- /dev/null
+++ b/file1.txt
@@ -0,0 +1,25 @@
+Alice Engineering Dept Robotics
+Bob Physics Dept Quantum Studies
+Charlie Chemistry Dept Polymers
+Diana Math Dept Applied Modeling
+Ethan Biology Dept Genetics Focus
+Fiona Economics Dept Global Trade
+George Literature Dept Classics
+Hannah History Dept Ancient World
+Ian Philosophy Dept Ethics
+Julia Music Dept Composition
+Kevin Art Dept Modern Painting
+Laura CS Dept Machine Learning
+Mark Stats Dept Data Analysis
+Nina Linguistics Dept Semantics
+Oliver Sociology Dept Inequality
+Paula Psychology Dept Cognition
+Quinn Anthropology Dept Culture
+Rachel Astronomy Dept Cosmology
+Steve PoliSci Dept Governance
+Tina EnvSci Dept Climate Studies
+Uma Business Dept Marketing
+Victor Education Dept Pedagogy
+Wendy Geography Dept GIS Mapping
+Xavier Law Dept International
+Yara Medicine Dept Physiology
diff --git a/file2.txt b/file2.txt
new file mode 100644
index 0000000..413c653
--- /dev/null
+++ b/file2.txt
@@ -0,0 +1,25 @@
+GradeA GPA3.9 HighPerformance
+GradeB GPA3.1 AveragePerformance
+GradeA GPA3.8 StrongPerformance
+GradeA GPA3.7 SolidPerformance
+GradeB GPA3.4 GoodPerformance
+GradeC GPA2.5 BelowPerformance
+GradeC GPA2.7 WeakPerformance
+GradeB GPA3.3 ConsistentWork
+GradeA GPA3.9 ExcellentWork
+GradeA GPA4.0 OutstandingWork
+GradeB GPA3.2 SatisfactoryWork
+GradeB GPA3.0 FairPerformance
+GradeA GPA3.5 StrongAnalysis
+GradeA GPA3.6 ClearThinking
+GradeB GPA3.4 GroupWorkGood
+GradeC GPA2.8 NeedsImprovement
+GradeC GPA2.6 PoorRetention
+GradeA GPA3.9 ExcellentResearch
+GradeA GPA3.8 HighAchievement
+GradeB GPA3.2 StableWork
+GradeB GPA3.0 AverageResults
+GradeA GPA3.8 GoodLearning
+GradeA GPA3.9 HighAccuracy
+GradeB GPA3.1 FairResults
+GradeB GPA3.3 SolidWork

From ef839f5472f9fb2f60c60b7dd05cae768fad43cf Mon Sep 17 00:00:00 2001
From: HECTOR NUNEZ <hnunez2@dons.usfca.edu>
Date: Wed, 24 Sep 2025 19:39:00 -0700
Subject: [PATCH 08/24] added functionality to output results to an output file
 in os

---
 Makefile     |  4 ++--
 grades.txt   |  5 +++++
 prices.txt   |  5 +++++
 products.txt |  5 +++++
 students.txt |  5 +++++
 user/join.c  | 46 +++++++++++++++++++++++++++++++---------------
 6 files changed, 53 insertions(+), 17 deletions(-)
 create mode 100644 grades.txt
 create mode 100644 prices.txt
 create mode 100644 products.txt
 create mode 100644 students.txt

diff --git a/Makefile b/Makefile
index 88f3211..2d9ed25 100644
--- a/Makefile
+++ b/Makefile
@@ -144,8 +144,8 @@ UPROGS=\
 	$U/_dorphan\
 	$U/_join\
 
-fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt
-	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt
+fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt
+	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt
 
 -include kernel/*.d user/*.d
 
diff --git a/grades.txt b/grades.txt
new file mode 100644
index 0000000..07b9dfb
--- /dev/null
+++ b/grades.txt
@@ -0,0 +1,5 @@
+001 A+ Excellent Outstanding
+002 B+ Good Solid
+003 A- Very Strong
+005 B Fair Average
+006 C Below Standard
diff --git a/prices.txt b/prices.txt
new file mode 100644
index 0000000..e98bf5e
--- /dev/null
+++ b/prices.txt
@@ -0,0 +1,5 @@
+P001 $999 Premium High
+P003 $599 Mid Reasonable
+P004 $299 Budget Low
+P007 $199 Clearance Sale
+P008 $149 Discount Special
diff --git a/products.txt b/products.txt
new file mode 100644
index 0000000..7d85455
--- /dev/null
+++ b/products.txt
@@ -0,0 +1,5 @@
+P001 Laptop Electronics Computing
+P002 Phone Mobile Communications
+P003 Tablet Portable Media
+P004 Watch Wearable Tech
+P005 Headphones Audio Sound
diff --git a/students.txt b/students.txt
new file mode 100644
index 0000000..7b57ae3
--- /dev/null
+++ b/students.txt
@@ -0,0 +1,5 @@
+001 Alice Engineering Robotics
+002 Bob Physics Quantum
+003 Charlie Chemistry Polymers
+004 Diana Math Modeling
+005 Ethan Biology Genetics
diff --git a/user/join.c b/user/join.c
index 533ec0d..11b7644 100644
--- a/user/join.c
+++ b/user/join.c
@@ -166,14 +166,17 @@
         void print_joined_line(int output_file, char* field, char* rest1, char* rest2){
             printf("%s %s %s\n", field, rest1, rest2);
 
-            // Write to the file
-            write(output_file, field, strlen(field));
-            write(output_file, " ", 1);
-            write(output_file, rest1, strlen(rest1));
-            write(output_file, " ", 1);
-            write(output_file, rest2, strlen(rest2));
-            write(output_file, "\n", 1);
+			// check if there is a valid file descriptor
+			if (output_file >= 0){
+            	// Write to the file 
+           		write(output_file, field, strlen(field));
+           		write(output_file, " ", 1);
+            	write(output_file, rest1, strlen(rest1));
+            	write(output_file, " ", 1);
+            	write(output_file, rest2, strlen(rest2));
+            	write(output_file, "\n", 1);
         }
+      }
     
     /**
      * Compares lines from both files and looks for matches in the 
@@ -182,12 +185,16 @@
     */
     void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file){
         int matches_found = 0;
+        int output_fd = -1;
 
         // Open the output file for writing (create it if it doesn't exist)
-        int output_fd = open(output_file, O_CREATE | O_RDWR);
+        if(output_file != 0){
+        	
+        output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC);
         if (output_fd < 0) {
             printf("Error: Cannot open output file '%s'\n", output_file);
             return;
+            }
         }
 
         // iterate through each line from file 1 
@@ -246,15 +253,20 @@
     }
 
 int main(int argc, char *argv[]){
+	// no output file before join
+	char* output_file = 0; 
     // ensure correct usage of command line args
-    if (argc != 3){
-        printf("Usage: join file1.txt file2.txt\n");
+    if (argc == 4){
+    	output_file = argv[3];
+    	printf("Joining files '%s' and '%s' -> output to '%s'...\n", argv[1], argv[2], argv[3]);
+	}else if (argc == 3){
+		printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
+	}
+    else{
+        printf("Usage: join file1.txt file2.txt [outputfile.txt]\n");
         exit(1);
     }
 
-    printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
-
-
     // read both files
     printf("Reading first file...");
     int count1 = read_file_lines(argv[1], file1_lines, 50);
@@ -273,8 +285,12 @@ int main(int argc, char *argv[]){
     }
     // join both files
     printf("joining both files\n");
-    join_files(file1_lines, count1, file2_lines, count2, "joined.txt");
-    printf("saving in a new file called joined.txt\n");
+    
+    join_files(file1_lines, count1, file2_lines, count2, output_file);
+    if(output_file != 0){
+    	printf("Output saved to %s\n", output_file);
+    }
+    
     printf("join completed\n");
 
     exit(0);

From 3aac05e7b743d124ed4f1e52eebdbf81af9331ed Mon Sep 17 00:00:00 2001
From: HECTOR NUNEZ <hnunez2@dons.usfca.edu>
Date: Thu, 25 Sep 2025 17:59:06 -0700
Subject: [PATCH 09/24] added comments to join.c

---
 user/join.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/user/join.c b/user/join.c
index 11b7644..8374218 100644
--- a/user/join.c
+++ b/user/join.c
@@ -184,13 +184,14 @@
      * If the fields match then print joined line
     */
     void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file){
-        int matches_found = 0;
-        int output_fd = -1;
+        int matches_found = 0; 		// count for amount of matches found
+        int output_fd = -1;			// value of file descriptor of output file (-1 no valid file)
 
         // Open the output file for writing (create it if it doesn't exist)
         if(output_file != 0){
-        	
-        output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC);
+        // changes the value of output_fd to indicate we have a valid file
+        output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC); 	// open file with flags (create new file if it does not exist | 
+        														      	//	write access only | empty file if already exists)
         if (output_fd < 0) {
             printf("Error: Cannot open output file '%s'\n", output_file);
             return;
@@ -201,6 +202,8 @@
         for (int i =0; i< count1; i++){
             char line1_copy[256]; // make copy to avoid messing with original
             int k = 0;
+
+            // string copy
             while (k<255 && file1_lines[i][k] != '\0'){
                 line1_copy[k] = file1_lines[i][k];
                 k++;
@@ -219,6 +222,8 @@
             for (int j =0; j < count2; j++){
                 char line2_copy[256]; // make copy to avoid messing with original
                 int m = 0;
+
+                // string copy
                 while (m<255 && file2_lines[j][m] != '\0'){
                     line2_copy[m] = file2_lines[j][m];
                     m++;
@@ -230,7 +235,7 @@
                 if(field2 == 0){
                     continue;
                 }
-                terminate_first_field(field2);
+                terminate_first_field(field2); // get rid of first word to make comparing easier
 
                 // check if both words are equal returns 0 if true
                 if(compare_strings(field1, field2) == 0){
@@ -240,11 +245,13 @@
                     char* rest1 = get_rest_of_line(file1_lines[i]);
                     char* rest2 = get_rest_of_line(file2_lines[j]);
 
+					// print using format
                     print_joined_line(output_fd, field1, rest1, rest2);
 
                 }
             }                
         }
+        // print message if no matches were found
         if(matches_found == 0){
             printf("No matches found\n");
         }
@@ -285,7 +292,7 @@ int main(int argc, char *argv[]){
     }
     // join both files
     printf("joining both files\n");
-    
+    // call function that joins files into output file
     join_files(file1_lines, count1, file2_lines, count2, output_file);
     if(output_file != 0){
     	printf("Output saved to %s\n", output_file);

From 90259f24f3324c88c93e9bb64df8024fa6107430 Mon Sep 17 00:00:00 2001
From: HECTOR NUNEZ <hnunez2@dons.usfca.edu>
Date: Thu, 25 Sep 2025 18:32:11 -0700
Subject: [PATCH 10/24] adding larger test files

---
 Fog_Emp.txt  | 40 ++++++++++++++++++++++++++++++++++++++++
 Fog_Perf.txt | 30 ++++++++++++++++++++++++++++++
 MC_Item.txt  | 45 +++++++++++++++++++++++++++++++++++++++++++++
 MC_Price.txt | 29 +++++++++++++++++++++++++++++
 Makefile     |  4 ++--
 5 files changed, 146 insertions(+), 2 deletions(-)
 create mode 100644 Fog_Emp.txt
 create mode 100644 Fog_Perf.txt
 create mode 100644 MC_Item.txt
 create mode 100644 MC_Price.txt

diff --git a/Fog_Emp.txt b/Fog_Emp.txt
new file mode 100644
index 0000000..300bcae
--- /dev/null
+++ b/Fog_Emp.txt
@@ -0,0 +1,40 @@
+EMP001 Alice Johnson Manager Sales Northeast
+EMP002 Bob Smith Developer IT Backend
+EMP003 Carol Davis Analyst Finance Budgets
+EMP004 David Wilson Designer Marketing Creative
+EMP005 Emma Brown Support Operations Customer
+EMP006 Frank Miller Engineer IT Systems
+EMP007 Grace Lee Specialist HR Recruiting
+EMP008 Henry Chen Coordinator Marketing Events
+EMP009 Iris Taylor Administrator Finance Payroll
+EMP010 Jack Rodriguez Developer IT Frontend
+EMP011 Kate Thompson Manager Operations Supply
+EMP012 Luis Garcia Analyst Data Business
+EMP013 Maria Gonzalez Designer UX Research
+EMP014 Nathan Park Engineer Software Senior
+EMP015 Olivia White Specialist Sales Enterprise
+EMP016 Paul Kim Coordinator HR Benefits
+EMP017 Quinn Adams Administrator IT Security
+EMP018 Rachel Turner Manager Finance Treasury
+EMP019 Samuel Lee Developer Mobile Applications
+EMP020 Tara Patel Analyst Marketing Consumer
+EMP021 Ulysses Jones Engineer DevOps Cloud
+EMP022 Victoria Chang Specialist Operations Logistics
+EMP023 William Hayes Coordinator Sales Regional
+EMP024 Ximena Rivera Administrator Marketing Social
+EMP025 Yuki Tanaka Manager IT Infrastructure
+EMP026 Zachary Moore Developer Full Stack
+EMP027 Abby Foster Analyst HR Metrics
+EMP028 Blake Cooper Engineer Quality Assurance
+EMP029 Chloe Ward Specialist Finance Audit
+EMP030 Dylan Scott Coordinator IT Help
+EMP031 Elena Morales Administrator Operations Facilities
+EMP032 Felix Chen Manager Sales International
+EMP033 Gina Roberts Developer Database Systems
+EMP034 Hugo Martinez Analyst Operations Process
+EMP035 Ivy Johnson Specialist Marketing Digital
+EMP036 Jake Williams Engineer Network Security
+EMP037 Kara Davis Coordinator Finance Accounting
+EMP038 Logan Brown Administrator HR Training
+EMP039 Mia Thompson Manager Operations Quality
+EMP040 Noah Garcia Developer API Services
diff --git a/Fog_Perf.txt b/Fog_Perf.txt
new file mode 100644
index 0000000..689f6ab
--- /dev/null
+++ b/Fog_Perf.txt
@@ -0,0 +1,30 @@
+EMP001 Excellent Rating5 Promotion Ready
+EMP003 Good Rating4 Steady Progress
+EMP005 Outstanding Rating5 Top Performer
+EMP007 Satisfactory Rating3 Meeting Goals
+EMP009 Excellent Rating5 Leadership Potential
+EMP011 Good Rating4 Strong Contributor
+EMP013 Outstanding Rating5 Innovation Leader
+EMP015 Satisfactory Rating3 Reliable Worker
+EMP017 Good Rating4 Technical Expert
+EMP019 Excellent Rating5 Rising Star
+EMP021 Outstanding Rating5 Architecture Lead
+EMP023 Satisfactory Rating3 Consistent Results
+EMP025 Excellent Rating5 Strategic Thinker
+EMP027 Good Rating4 Data Expert
+EMP029 Outstanding Rating5 Process Optimizer
+EMP031 Satisfactory Rating3 Team Player
+EMP033 Excellent Rating5 Database Guru
+EMP035 Good Rating4 Creative Marketer
+EMP037 Outstanding Rating5 Financial Wizard
+EMP039 Satisfactory Rating3 Quality Focused
+EMP002 Good Rating4 Code Quality
+EMP004 Excellent Rating5 Design Leader
+EMP006 Outstanding Rating5 System Architect
+EMP008 Satisfactory Rating3 Event Success
+EMP010 Good Rating4 Frontend Expert
+EMP012 Excellent Rating5 Analytics Pro
+EMP014 Outstanding Rating5 Senior Mentor
+EMP016 Satisfactory Rating3 Benefits Admin
+EMP018 Good Rating4 Treasury Manager
+EMP020 Excellent Rating5 Market Researcher
diff --git a/MC_Item.txt b/MC_Item.txt
new file mode 100644
index 0000000..225b5a7
--- /dev/null
+++ b/MC_Item.txt
@@ -0,0 +1,45 @@
+SKU1001 Laptop Dell Inspiron 15
+SKU1002 Monitor Samsung 27inch 4K
+SKU1003 Keyboard Mechanical RGB Gaming
+SKU1004 Mouse Wireless Ergonomic Office
+SKU1005 Headphones Noise Cancelling Premium
+SKU1006 Webcam HD 1080p Conference
+SKU1007 Printer Laser Color Network
+SKU1008 Scanner Flatbed Document High
+SKU1009 Tablet iPad Pro 12inch
+SKU1010 Smartphone iPhone 15 Pro
+SKU1011 Smartwatch Apple Watch Series
+SKU1012 Speaker Bluetooth Portable Waterproof
+SKU1013 Charger USB-C Fast Wireless
+SKU1014 Cable HDMI 4K Premium
+SKU1015 Adapter USB Hub Multi
+SKU1016 Drive SSD External 1TB
+SKU1017 Memory RAM DDR4 32GB
+SKU1018 Graphics Card RTX 4080
+SKU1019 Processor Intel i7 13th
+SKU1020 Motherboard ASUS Gaming ATX
+SKU1021 Case PC Tower RGB
+SKU1022 Fan Cooling Liquid AIO
+SKU1023 Power Supply 850W Modular
+SKU1024 Router WiFi 6 Mesh
+SKU1025 Switch Network 24 Port
+SKU1026 Camera DSLR Canon Professional
+SKU1027 Lens Telephoto 70-200mm Canon
+SKU1028 Tripod Carbon Fiber Professional
+SKU1029 Light LED Panel Studio
+SKU1030 Microphone USB Condenser Podcast
+SKU1031 Interface Audio USB Recording
+SKU1032 Mixer Digital 8 Channel
+SKU1033 Drone Quadcopter 4K Camera
+SKU1034 Battery Drone LiPo 3S
+SKU1035 Controller Game Wireless Pro
+SKU1036 Console Gaming Latest Generation
+SKU1037 Headset Gaming Surround 7.1
+SKU1038 Chair Gaming Ergonomic Racing
+SKU1039 Desk Gaming L-Shaped Standing
+SKU1040 Monitor Arm Dual Display
+SKU1041 Lamp Desk LED Adjustable
+SKU1042 Fan Desk USB Quiet
+SKU1043 Heater Space Ceramic Safety
+SKU1044 Purifier Air HEPA Smart
+SKU1045 Humidifier Ultrasonic Cool Mist
diff --git a/MC_Price.txt b/MC_Price.txt
new file mode 100644
index 0000000..604d552
--- /dev/null
+++ b/MC_Price.txt
@@ -0,0 +1,29 @@
+SKU1001 $899.99 InStock Warehouse-A
+SKU1003 $149.99 InStock Warehouse-B
+SKU1005 $299.99 LowStock Warehouse-A
+SKU1007 $449.99 InStock Warehouse-C
+SKU1009 $1099.99 OutOfStock Backorder
+SKU1011 $399.99 InStock Warehouse-A
+SKU1013 $79.99 InStock Warehouse-B
+SKU1015 $49.99 InStock Warehouse-C
+SKU1017 $189.99 LowStock Warehouse-A
+SKU1019 $329.99 InStock Warehouse-B
+SKU1021 $129.99 InStock Warehouse-C
+SKU1023 $159.99 LowStock Warehouse-A
+SKU1025 $299.99 InStock Warehouse-B
+SKU1027 $899.99 OutOfStock Backorder
+SKU1029 $199.99 InStock Warehouse-C
+SKU1031 $149.99 InStock Warehouse-A
+SKU1033 $599.99 LowStock Warehouse-B
+SKU1035 $69.99 InStock Warehouse-C
+SKU1037 $199.99 InStock Warehouse-A
+SKU1039 $399.99 LowStock Warehouse-B
+SKU1041 $89.99 InStock Warehouse-C
+SKU1043 $79.99 InStock Warehouse-A
+SKU1045 $129.99 InStock Warehouse-B
+SKU1002 $349.99 InStock Warehouse-A
+SKU1004 $59.99 InStock Warehouse-B
+SKU1006 $89.99 LowStock Warehouse-C
+SKU1008 $249.99 InStock Warehouse-A
+SKU1010 $999.99 InStock Warehouse-B
+SKU1012 $99.99 InStock Warehouse-C
diff --git a/Makefile b/Makefile
index 2d9ed25..59646e5 100644
--- a/Makefile
+++ b/Makefile
@@ -144,8 +144,8 @@ UPROGS=\
 	$U/_dorphan\
 	$U/_join\
 
-fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt
-	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt
+fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt 
+	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt
 
 -include kernel/*.d user/*.d
 

From d60e143dae0a369b92f17fbc7cd81c3b7f2fd9d0 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Fri, 26 Sep 2025 18:52:27 -0700
Subject: [PATCH 11/24] Fix: minor indentation @user/join.c

---
 user/join.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/user/join.c b/user/join.c
index 8374218..883eedc 100644
--- a/user/join.c
+++ b/user/join.c
@@ -175,7 +175,7 @@
             	write(output_file, " ", 1);
             	write(output_file, rest2, strlen(rest2));
             	write(output_file, "\n", 1);
-        }
+            }
       }
     
     /**
@@ -189,12 +189,12 @@
 
         // Open the output file for writing (create it if it doesn't exist)
         if(output_file != 0){
-        // changes the value of output_fd to indicate we have a valid file
-        output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC); 	// open file with flags (create new file if it does not exist | 
-        														      	//	write access only | empty file if already exists)
-        if (output_fd < 0) {
-            printf("Error: Cannot open output file '%s'\n", output_file);
-            return;
+            // changes the value of output_fd to indicate we have a valid file
+            output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC); 	// open file with flags (create new file if it does not exist | 
+            														      	//	write access only | empty file if already exists)
+            if (output_fd < 0) {
+                printf("Error: Cannot open output file '%s'\n", output_file);
+                return;
             }
         }
 
@@ -268,8 +268,7 @@ int main(int argc, char *argv[]){
     	printf("Joining files '%s' and '%s' -> output to '%s'...\n", argv[1], argv[2], argv[3]);
 	}else if (argc == 3){
 		printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
-	}
-    else{
+	}else{
         printf("Usage: join file1.txt file2.txt [outputfile.txt]\n");
         exit(1);
     }
@@ -286,7 +285,7 @@ int main(int argc, char *argv[]){
     printf("Reading second file...");
     int count2 = read_file_lines(argv[2], file2_lines, 50);
     printf("Read %d lines from file2\n", count2);
-        if(count2 == 0){
+    if(count2 == 0){
     	printf("ERROR: failed to read lines from %s\n", argv[2]);
     	exit(1);
     }

From 1965e9bafd944a206a3f78b5599587333d088b67 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Fri, 26 Sep 2025 19:39:22 -0700
Subject: [PATCH 12/24] Feature: Added empty txt checking and minor syntax
 fixing

---
 user/join.c | 69 +++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 48 insertions(+), 21 deletions(-)

diff --git a/user/join.c b/user/join.c
index 883eedc..3c09611 100644
--- a/user/join.c
+++ b/user/join.c
@@ -111,10 +111,22 @@
      */
     int read_file_lines(char* filename, char lines[][256], int max_count) {
         int file = open(filename, 0); // 0 = O_RDONLY
+        struct stat st; // stat struct contains a member called size, which holds the file's size in bytes
+        
         if (file < 0) {
-            printf("Error: Cannot open file '%s'\n", filename);
+            close(file);
             return 0;
         }
+
+        if (fstat(file, &st) < 0) { //check metadata
+            close(file);
+            return -1;
+        }
+
+        if (st.size == 0) { //check size to see if empty txt or not, join does not work if any or both files empty
+            close(file);
+            return -2;
+        }
         
         int line_count = 0;
         char buffer[256];
@@ -163,11 +175,11 @@
          * function prints joined line 
          * "first word" "rest line file 1" "rest line file 2"
         */
-        void print_joined_line(int output_file, char* field, char* rest1, char* rest2){
+        void print_joined_line(int output_file, char* field, char* rest1, char* rest2) {
             printf("%s %s %s\n", field, rest1, rest2);
 
 			// check if there is a valid file descriptor
-			if (output_file >= 0){
+			if (output_file >= 0) {
             	// Write to the file 
            		write(output_file, field, strlen(field));
            		write(output_file, " ", 1);
@@ -183,12 +195,12 @@
      * first field
      * If the fields match then print joined line
     */
-    void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file){
+    void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file) {
         int matches_found = 0; 		// count for amount of matches found
         int output_fd = -1;			// value of file descriptor of output file (-1 no valid file)
 
         // Open the output file for writing (create it if it doesn't exist)
-        if(output_file != 0){
+        if(output_file != 0) {
             // changes the value of output_fd to indicate we have a valid file
             output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC); 	// open file with flags (create new file if it does not exist | 
             														      	//	write access only | empty file if already exists)
@@ -199,12 +211,12 @@
         }
 
         // iterate through each line from file 1 
-        for (int i =0; i< count1; i++){
+        for (int i =0; i< count1; i++) {
             char line1_copy[256]; // make copy to avoid messing with original
             int k = 0;
 
             // string copy
-            while (k<255 && file1_lines[i][k] != '\0'){
+            while (k<255 && file1_lines[i][k] != '\0') {
                 line1_copy[k] = file1_lines[i][k];
                 k++;
             }
@@ -212,19 +224,19 @@
             
             char* field1 = get_first_field(line1_copy); // reads full line but only gets first word to check for match
             // skip is field is empty 
-            if(field1 == 0){
+            if(field1 == 0) {
                 continue;
             }
 
             terminate_first_field(field1); // get rid of first word to make comparing easier
 
             // iterate through lines in file two 
-            for (int j =0; j < count2; j++){
+            for (int j =0; j < count2; j++) {
                 char line2_copy[256]; // make copy to avoid messing with original
                 int m = 0;
 
                 // string copy
-                while (m<255 && file2_lines[j][m] != '\0'){
+                while (m<255 && file2_lines[j][m] != '\0') {
                     line2_copy[m] = file2_lines[j][m];
                     m++;
                 }
@@ -232,13 +244,13 @@
                             
                 char* field2 = get_first_field(line2_copy); // read full line but only gets first word
                 // skip if field is empty
-                if(field2 == 0){
+                if(field2 == 0) {
                     continue;
                 }
                 terminate_first_field(field2); // get rid of first word to make comparing easier
 
                 // check if both words are equal returns 0 if true
-                if(compare_strings(field1, field2) == 0){
+                if(compare_strings(field1, field2) == 0) {
                     matches_found++;
                 
                     // get rest of lines for both files from where we got field
@@ -252,23 +264,23 @@
             }                
         }
         // print message if no matches were found
-        if(matches_found == 0){
+        if(matches_found == 0) {
             printf("No matches found\n");
         }
         // Close the output file
         close(output_fd);
     }
 
-int main(int argc, char *argv[]){
+int main(int argc, char *argv[]) {
 	// no output file before join
 	char* output_file = 0; 
     // ensure correct usage of command line args
-    if (argc == 4){
+    if (argc == 4) {
     	output_file = argv[3];
     	printf("Joining files '%s' and '%s' -> output to '%s'...\n", argv[1], argv[2], argv[3]);
-	}else if (argc == 3){
+	} else if (argc == 3) {
 		printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
-	}else{
+	} else {
         printf("Usage: join file1.txt file2.txt [outputfile.txt]\n");
         exit(1);
     }
@@ -277,23 +289,38 @@ int main(int argc, char *argv[]){
     printf("Reading first file...");
     int count1 = read_file_lines(argv[1], file1_lines, 50);
     printf("Read %d lines from file1\n", count1);
-    if(count1 == 0){
+    if(count1 == 0) {
     	printf("ERROR: failed to read lines from %s\n", argv[1]);
     	exit(1);
+    } else if(count1 == -1) {
+        printf("ERROR: failed to retrive metadata from %s\n", argv[1]);
+        exit(1);
+    } else if(count1 == -2) {
+        printf("ERROR: %s is empty\n", argv[1]);
+        exit(1);
+    } else {
+         printf("File %s exists\n", argv[1]);
     }
-
+    
     printf("Reading second file...");
     int count2 = read_file_lines(argv[2], file2_lines, 50);
     printf("Read %d lines from file2\n", count2);
-    if(count2 == 0){
+    if(count2 == 0) {
     	printf("ERROR: failed to read lines from %s\n", argv[2]);
     	exit(1);
+    }else if(count1 == -1) {
+        printf("ERROR: failed to retrive metadata from %s\n", argv[2]);
+        exit(1);
+    }else if(count1 == -2) {
+        printf("ERROR: %s is empty\n", argv[2]);
+        exit(1);
     }
+    
     // join both files
     printf("joining both files\n");
     // call function that joins files into output file
     join_files(file1_lines, count1, file2_lines, count2, output_file);
-    if(output_file != 0){
+    if(output_file != 0) {
     	printf("Output saved to %s\n", output_file);
     }
     

From f2e40db80cfc36e859f39438eb508d0f4137408c Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Fri, 26 Sep 2025 19:47:12 -0700
Subject: [PATCH 13/24] Fix: minor output fix

---
 user/join.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/user/join.c b/user/join.c
index 3c09611..ae4dd48 100644
--- a/user/join.c
+++ b/user/join.c
@@ -288,7 +288,7 @@ int main(int argc, char *argv[]) {
     // read both files
     printf("Reading first file...");
     int count1 = read_file_lines(argv[1], file1_lines, 50);
-    printf("Read %d lines from file1\n", count1);
+    printf("Read %d lines from file 1\n", count1);
     if(count1 == 0) {
     	printf("ERROR: failed to read lines from %s\n", argv[1]);
     	exit(1);
@@ -304,7 +304,7 @@ int main(int argc, char *argv[]) {
     
     printf("Reading second file...");
     int count2 = read_file_lines(argv[2], file2_lines, 50);
-    printf("Read %d lines from file2\n", count2);
+    printf("Read %d lines from file 2\n", count2);
     if(count2 == 0) {
     	printf("ERROR: failed to read lines from %s\n", argv[2]);
     	exit(1);

From e94b663069eff098ca8e7f2663f49d3d78048b91 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Fri, 26 Sep 2025 20:27:15 -0700
Subject: [PATCH 14/24] Test Case: Adding an empty txt test case

---
 Makefile  | 4 ++--
 empty.txt | 0
 2 files changed, 2 insertions(+), 2 deletions(-)
 create mode 100644 empty.txt

diff --git a/Makefile b/Makefile
index 59646e5..b093679 100644
--- a/Makefile
+++ b/Makefile
@@ -144,8 +144,8 @@ UPROGS=\
 	$U/_dorphan\
 	$U/_join\
 
-fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt 
-	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt
+fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt empty.txt
+	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt empty.txt
 
 -include kernel/*.d user/*.d
 
diff --git a/empty.txt b/empty.txt
new file mode 100644
index 0000000..e69de29

From b1f84f4d309a1db757c4e70df05af0639df91fe8 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Fri, 26 Sep 2025 20:29:07 -0700
Subject: [PATCH 15/24] Fix: changed a variable identifier name to fix logic
 error

---
 user/join.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/user/join.c b/user/join.c
index ae4dd48..cde6a0f 100644
--- a/user/join.c
+++ b/user/join.c
@@ -286,9 +286,8 @@ int main(int argc, char *argv[]) {
     }
 
     // read both files
-    printf("Reading first file...");
+    printf("Attempting to read first file...\n");
     int count1 = read_file_lines(argv[1], file1_lines, 50);
-    printf("Read %d lines from file 1\n", count1);
     if(count1 == 0) {
     	printf("ERROR: failed to read lines from %s\n", argv[1]);
     	exit(1);
@@ -299,21 +298,24 @@ int main(int argc, char *argv[]) {
         printf("ERROR: %s is empty\n", argv[1]);
         exit(1);
     } else {
-         printf("File %s exists\n", argv[1]);
+        printf("File %s exists\n", argv[1]);
+        printf("Read %d lines from file 1\n", count1);
     }
     
-    printf("Reading second file...");
+    printf("Attempting to read second file...\n");
     int count2 = read_file_lines(argv[2], file2_lines, 50);
-    printf("Read %d lines from file 2\n", count2);
     if(count2 == 0) {
     	printf("ERROR: failed to read lines from %s\n", argv[2]);
     	exit(1);
-    }else if(count1 == -1) {
+    } else if(count2 == -1) {
         printf("ERROR: failed to retrive metadata from %s\n", argv[2]);
         exit(1);
-    }else if(count1 == -2) {
+    } else if(count2 == -2) {
         printf("ERROR: %s is empty\n", argv[2]);
         exit(1);
+    } else {
+        printf("File %s exists\n", argv[2]);
+        printf("Read %d lines from file 2\n", count2);
     }
     
     // join both files

From 1cab6fed953243c0ee92b755e6abc3b4170f6282 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 1 Oct 2025 16:20:03 -0700
Subject: [PATCH 16/24] Feature: MakeFile can now pick up all the test files
 from its own folder

---
 Makefile | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index b093679..94ecd48 100644
--- a/Makefile
+++ b/Makefile
@@ -144,19 +144,26 @@ UPROGS=\
 	$U/_dorphan\
 	$U/_join\
 
-fs.img: mkfs/mkfs README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt empty.txt
+TDIR = tests
+
+fs.img: mkfs/mkfs README.md $(UPROGS) $(TDIR)/file1.txt $(TDIR)/file2.txt $(TDIR)/students.txt $(TDIR)/grades.txt $(TDIR)/products.txt $(TDIR)/prices.txt $(TDIR)/Fog_Emp.txt $(TDIR)/Fog_Perf.txt $(TDIR)/MC_Item.txt $(TDIR)/MC_Price.txt $(TDIR)/empty.txt
+	cp $(TDIR)/*.txt .
 	mkfs/mkfs fs.img README.md $(UPROGS) file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt empty.txt
 
 -include kernel/*.d user/*.d
 
 clean: 
-	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
+	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg file1.txt file2.txt students.txt grades.txt products.txt prices.txt Fog_Emp.txt Fog_Perf.txt MC_Item.txt MC_Price.txt empty.txt \
 	*/*.o */*.d */*.asm */*.sym \
 	$K/kernel fs.img \
 	mkfs/mkfs .gdbinit \
         $U/usys.S \
 	$(UPROGS)
 
+qemu-clean: check-qemu-version $K/kernel fs.img
+	$(QEMU) $(QEMUOPTS)
+	$(MAKE) clean
+
 # try to generate a unique GDB port
 GDBPORT = $(shell expr `id -u` % 5000 + 25000)
 # QEMU's gdb stub command line changed in 0.11

From b67a45d6c1be8677a2eed7bcf0ac3b0c85791aa9 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 1 Oct 2025 16:21:19 -0700
Subject: [PATCH 17/24] Restructure: Moving all the txt files from root into
 tests dir

---
 Fog_Emp.txt => tests/Fog_Emp.txt   | 0
 Fog_Perf.txt => tests/Fog_Perf.txt | 0
 MC_Item.txt => tests/MC_Item.txt   | 0
 MC_Price.txt => tests/MC_Price.txt | 0
 empty.txt => tests/empty.txt       | 0
 file1.txt => tests/file1.txt       | 0
 file2.txt => tests/file2.txt       | 0
 grades.txt => tests/grades.txt     | 0
 prices.txt => tests/prices.txt     | 0
 products.txt => tests/products.txt | 0
 students.txt => tests/students.txt | 0
 11 files changed, 0 insertions(+), 0 deletions(-)
 rename Fog_Emp.txt => tests/Fog_Emp.txt (100%)
 rename Fog_Perf.txt => tests/Fog_Perf.txt (100%)
 rename MC_Item.txt => tests/MC_Item.txt (100%)
 rename MC_Price.txt => tests/MC_Price.txt (100%)
 rename empty.txt => tests/empty.txt (100%)
 rename file1.txt => tests/file1.txt (100%)
 rename file2.txt => tests/file2.txt (100%)
 rename grades.txt => tests/grades.txt (100%)
 rename prices.txt => tests/prices.txt (100%)
 rename products.txt => tests/products.txt (100%)
 rename students.txt => tests/students.txt (100%)

diff --git a/Fog_Emp.txt b/tests/Fog_Emp.txt
similarity index 100%
rename from Fog_Emp.txt
rename to tests/Fog_Emp.txt
diff --git a/Fog_Perf.txt b/tests/Fog_Perf.txt
similarity index 100%
rename from Fog_Perf.txt
rename to tests/Fog_Perf.txt
diff --git a/MC_Item.txt b/tests/MC_Item.txt
similarity index 100%
rename from MC_Item.txt
rename to tests/MC_Item.txt
diff --git a/MC_Price.txt b/tests/MC_Price.txt
similarity index 100%
rename from MC_Price.txt
rename to tests/MC_Price.txt
diff --git a/empty.txt b/tests/empty.txt
similarity index 100%
rename from empty.txt
rename to tests/empty.txt
diff --git a/file1.txt b/tests/file1.txt
similarity index 100%
rename from file1.txt
rename to tests/file1.txt
diff --git a/file2.txt b/tests/file2.txt
similarity index 100%
rename from file2.txt
rename to tests/file2.txt
diff --git a/grades.txt b/tests/grades.txt
similarity index 100%
rename from grades.txt
rename to tests/grades.txt
diff --git a/prices.txt b/tests/prices.txt
similarity index 100%
rename from prices.txt
rename to tests/prices.txt
diff --git a/products.txt b/tests/products.txt
similarity index 100%
rename from products.txt
rename to tests/products.txt
diff --git a/students.txt b/tests/students.txt
similarity index 100%
rename from students.txt
rename to tests/students.txt

From 8d3025d638ea2eba57a5b14020729f853699b958 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 1 Oct 2025 16:36:21 -0700
Subject: [PATCH 18/24] Feature: Documentation shows up on README.md page on
 github

---
 README.md             |  3 +-
 docs/Documentation.md | 68 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 docs/Documentation.md

diff --git a/README.md b/README.md
index 85f6164..70988fa 100644
--- a/README.md
+++ b/README.md
@@ -4,4 +4,5 @@ Fall 2025 Edition
 
 ![FogOS](docs/fogos.gif)
 
-
+## Documentation
+[Documentation](docs/Documentation.md)
diff --git a/docs/Documentation.md b/docs/Documentation.md
new file mode 100644
index 0000000..916a0e9
--- /dev/null
+++ b/docs/Documentation.md
@@ -0,0 +1,68 @@
+# Software Documentation
+
+## Building the Software
+
+### Build Steps
+```bash
+make
+```
+This will:
+- Compile the kernel from source files in the `kernel/` directory
+- Compile user programs from the `user/` directory
+- Copy test data files from `tests/` to the root directory
+- Create the filesystem image (`fs.img`) containing all programs and data files
+
+## Running the Software
+
+### Start QEMU
+```bash
+make qemu
+```
+This launches the RISC-V emulator with the compiled kernel and filesystem.
+
+### Exit QEMU
+Press `Ctrl+A` then `X` to quit the emulator.
+
+### Run with automatic cleanup [OPTIONAL]
+```bash
+make qemu-clean
+```
+This runs QEMU and automatically cleans build artifacts after you exit.
+
+## Testing the Software
+
+### Access test data files
+Once in QEMU, the test data files are available in the filesystem:
+- `file1.txt`, `file2.txt` - Sample department data
+- `MC_Item.txt`, `MC_Price.txt` - Inventory data
+- `students.txt`, `grades.txt` - Student records
+- `products.txt`, `prices.txt` - Product information
+- `Fog_Emp.txt`, `Fog_Perf.txt` - Employee data
+- `empty.txt` - Empty test file
+
+### Run built-in test programs
+The system includes several test programs in `/user`:
+- `usertests` - Comprehensive system tests
+- `forktest` - Process creation tests
+- `grind` - Stress testing
+
+## Cleaning Up
+
+### Remove all build artifacts and copied test files
+```bash
+make clean
+```
+This removes:
+- Compiled object files (*.o)
+- Kernel binary and filesystem image
+- Temporary files
+- Test data files copied to root (preserves originals in `testData/`)
+- Note: `compile_flags.txt` in root is preserved
+
+## Project Structure
+
+- `kernel/` - Operating system kernel source code
+- `user/` - User-space programs and utilities
+- `testData/` - Original test data files (preserved during clean)
+- `mkfs/` - Filesystem creation utility
+- `Makefile` - Build configuration and targets

From a412e195794d273de2cb5df7d96e77d3fcb0bd97 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 1 Oct 2025 16:40:42 -0700
Subject: [PATCH 19/24] Edit: README.md layout edit for ease of access to
 Documentation

---
 README.md | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 70988fa..e0035be 100644
--- a/README.md
+++ b/README.md
@@ -5,4 +5,26 @@ Fall 2025 Edition
 ![FogOS](docs/fogos.gif)
 
 ## Documentation
-[Documentation](docs/Documentation.md)
+
+### Quick Links
+- [Building the Software](docs/Documentation.md#building-the-software)
+- [Running the Software](docs/Documentation.md#running-the-software)
+- [Testing the Software](docs/Documentation.md#testing-the-software)
+- [Cleaning Up](docs/Documentation.md#cleaning-up)
+- [Project Structure](docs/Documentation.md#project-structure)
+
+### Quick Start
+```bash
+# Build the project
+make
+
+# Run QEMU
+make qemu
+
+# Exit: Ctrl+A then X
+
+# Clean up
+make clean
+```
+
+For detailed documentation, see [Documentation.md](docs/Documentation.md)

From 7d810e885bb95c48fd6ffbdcbe7ed9af198895ff Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Wed, 1 Oct 2025 16:48:42 -0700
Subject: [PATCH 20/24] Edit: Correcting some errors in documentation

---
 docs/Documentation.md | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/docs/Documentation.md b/docs/Documentation.md
index 916a0e9..140a94a 100644
--- a/docs/Documentation.md
+++ b/docs/Documentation.md
@@ -40,11 +40,16 @@ Once in QEMU, the test data files are available in the filesystem:
 - `Fog_Emp.txt`, `Fog_Perf.txt` - Employee data
 - `empty.txt` - Empty test file
 
-### Run built-in test programs
-The system includes several test programs in `/user`:
-- `usertests` - Comprehensive system tests
-- `forktest` - Process creation tests
-- `grind` - Stress testing
+### Run join command
+You can test the join functionality with two input files:
+```bash
+join file1.txt file2.txt
+```
+
+You can also specify an output file:
+```bash
+join file1.txt file2.txt output.txt
+```
 
 ## Cleaning Up
 
@@ -63,6 +68,6 @@ This removes:
 
 - `kernel/` - Operating system kernel source code
 - `user/` - User-space programs and utilities
-- `testData/` - Original test data files (preserved during clean)
+- `tests/` - Original test data files (preserved during clean)
 - `mkfs/` - Filesystem creation utility
 - `Makefile` - Build configuration and targets

From c7db0d5c32f1bf846277844f19ef8a9202359ee5 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Mon, 6 Oct 2025 04:14:29 -0700
Subject: [PATCH 21/24] Added clear explanation of what join does, how it
 works, and expected output format with examples

---
 docs/Documentation.md | 50 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 44 insertions(+), 6 deletions(-)

diff --git a/docs/Documentation.md b/docs/Documentation.md
index 140a94a..10193f0 100644
--- a/docs/Documentation.md
+++ b/docs/Documentation.md
@@ -2,6 +2,11 @@
 
 ## Building the Software
 
+### Prerequisites
+- RISC-V toolchain (riscv64-unknown-elf-gcc or riscv64-linux-gnu-gcc)
+- QEMU RISC-V emulator (version 7.2 or higher)
+- Make build system
+
 ### Build Steps
 ```bash
 make
@@ -9,7 +14,7 @@ make
 This will:
 - Compile the kernel from source files in the `kernel/` directory
 - Compile user programs from the `user/` directory
-- Copy test data files from `tests/` to the root directory
+- Copy test data files from `testData/` to the root directory
 - Create the filesystem image (`fs.img`) containing all programs and data files
 
 ## Running the Software
@@ -23,7 +28,9 @@ This launches the RISC-V emulator with the compiled kernel and filesystem.
 ### Exit QEMU
 Press `Ctrl+A` then `X` to quit the emulator.
 
-### Run with automatic cleanup [OPTIONAL]
+**Important:** After exiting QEMU, run `make clean` to remove build artifacts and copied test files.
+
+### Run with automatic cleanup
 ```bash
 make qemu-clean
 ```
@@ -31,9 +38,15 @@ This runs QEMU and automatically cleans build artifacts after you exit.
 
 ## Testing the Software
 
+### Understanding the join command
+The `join` command merges two text files based on matching first fields (words) in each line. For each match found, it outputs a combined line in the format:
+```
+<matching_field> <rest_of_line_from_file1> <rest_of_line_from_file2>
+```
+
 ### Access test data files
 Once in QEMU, the test data files are available in the filesystem:
-- `file1.txt`, `file2.txt` - Sample department data
+- `file1.txt`, `file2.txt` - Sample department data (25 lines each)
 - `MC_Item.txt`, `MC_Price.txt` - Inventory data
 - `students.txt`, `grades.txt` - Student records
 - `products.txt`, `prices.txt` - Product information
@@ -41,15 +54,40 @@ Once in QEMU, the test data files are available in the filesystem:
 - `empty.txt` - Empty test file
 
 ### Run join command
-You can test the join functionality with two input files:
+
+**Basic usage (output to console):**
 ```bash
 join file1.txt file2.txt
 ```
+Expected output: 25 joined lines matching names from both files, displaying department info with grades.
 
-You can also specify an output file:
+**With output file:**
 ```bash
 join file1.txt file2.txt output.txt
 ```
+This saves the joined results to `output.txt` while also displaying them on console.
+
+**Get help:**
+```bash
+join --help
+```
+
+**Example output format:**
+When joining students.txt and grades.txt, each matching line combines:
+- The matching first field (e.g., "001")
+- The remainder of the line from students.txt (e.g., "Alice Engineering Robotics")
+- The remainder of the line from grades.txt (e.g., "A+ Excellent Outstanding")
+
+```
+001 Alice Engineering Robotics A+ Excellent Outstanding
+002 Bob Physics Quantum B+ Good Solid
+003 Charlie Chemistry Polymers A- Very Strong
+005 Ethan Biology Genetics B Fair Average
+join completed
+...
+```
+
+The output shows 4 total matches (one for each person in both files).
 
 ## Cleaning Up
 
@@ -68,6 +106,6 @@ This removes:
 
 - `kernel/` - Operating system kernel source code
 - `user/` - User-space programs and utilities
-- `tests/` - Original test data files (preserved during clean)
+- `testData/` - Original test data files (preserved during clean)
 - `mkfs/` - Filesystem creation utility
 - `Makefile` - Build configuration and targets

From 93c7017dd06437a3023a0001ff0ac0bccac595a0 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Mon, 6 Oct 2025 04:42:28 -0700
Subject: [PATCH 22/24] Added --help flag and fixed indentation and formatting
 inconsistencies throughout join.c

---
 user/join.c | 554 +++++++++++++++++++++++++++-------------------------
 1 file changed, 283 insertions(+), 271 deletions(-)

diff --git a/user/join.c b/user/join.c
index cde6a0f..7ccb79a 100644
--- a/user/join.c
+++ b/user/join.c
@@ -4,329 +4,341 @@
 #include "kernel/fcntl.h"
 
 
-    // // Hector's functions
-     //void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file));
-     //void print_joined_line(int output_file, char* field, char* rest1, char* rest2);
-     //char* get_rest_of_line(char* line);
-    // 
-    // 
-    // // Demetrius's functions
-     //char* get_first_field(char* line);
-    // int read_file_lines(char* filename, char lines[][256], int count2);
-
-     // helper functions 
-    //compare_strings(char* str1, char* str2)
-    //terminate_first_field(char* line)
+// // Hector's functions
+//void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file));
+//void print_joined_line(int output_file, char* field, char* rest1, char* rest2);
+//char* get_rest_of_line(char* line);
+// 
+// 
+// // Demetrius's functions
+//char* get_first_field(char* line);
+// int read_file_lines(char* filename, char lines[][256], int count2);
+
+// helper functions 
+//compare_strings(char* str1, char* str2)
+//terminate_first_field(char* line)
+
+/**
+ * String comparison iterates through each char in both
+ * strings to see if they match if non return non-zero
+ */
+
+static char file1_lines[50][256];
+static char file2_lines[50][256];
+
+int compare_strings(char* str1, char* str2) {
+    while (*str1 && *str2) {
+        if (*str1 != *str2) {
+            return *str1 - *str2;
+        }
+        str1++;
+        str2++;
+    }
+    return *str1 - *str2;
+}
+
+/**
+ * Extracts the first field (word) from a line
+ * Returns a pointer to the first field, or NULL if line is empty
+ */
+
+char* get_first_field(char* line) {
+    if (line == 0 || *line == '\0') {
+        return 0;
+    }
+    
+    // Skip leading whitespace
+    while (*line == ' ' || *line == '\t') {
+        line++;
+    }
     
-    /**
-     * String comparison iterates through each char in both
-     * strings to see if they match if non return non-zero
-     */
-
-    static char file1_lines[50][256];
-    static char file2_lines[50][256];
-
-    int compare_strings(char* str1, char* str2){
-    	while (*str1 && *str2){
-    		if (*str1 != *str2){
-    			return *str1 - *str2;
-    		}
-    		str1++;
-    		str2++;
-    	}
-    	return *str1 - *str2;
+    // If line is empty after skipping whitespace
+    if (*line == '\0') {
+        return 0;
     }
+    
+    return line;
+}
 
-     /**
-     * Extracts the first field (word) from a line
-     * Returns a pointer to the first field, or NULL if line is empty
-     */
+/**
+ * Function to get the rest of the line so it is everything 
+ * after the first word 
+*/
+char* get_rest_of_line(char* line) {
 
-    char* get_first_field(char* line) {
-        if (line == 0 || *line == '\0') {
-            return 0;
-        }
-        
-        // Skip leading whitespace
-        while (*line == ' ' || *line == '\t') {
-            line++;
-        }
-        
-        // If line is empty after skipping whitespace
-        if (*line == '\0') {
-            return 0;
-        }
-        
-        return line;
+    // return empty if line is not valid
+    if(line == 0 || *line == '\0') {
+        return "";
     }
 
-    /**
-     * Function to get the rest of the line so it is everything 
-     * after the first word 
-    */
-    char* get_rest_of_line(char* line){
+    char* ptr = line;
+    // skip leading whitespace
+    while(*ptr ==  ' ' || *ptr == '\t') {
+        ptr++;
+    }
+    // skip first field until reached whitespace or end of line
+    while (*ptr != '\0' && *ptr != ' ' && *ptr != '\t' ) {
+        ptr++;
+    }
+    // skip whitespace between first field and rest
+    while(*ptr == ' ' || *ptr == '\t') {
+        ptr++;
+    }
+    return ptr;
+}
 
-        // return empty if line is not valid
-        if(line == 0 || *line == '\0'){
-            return "";
-        }
+void terminate_first_field(char* line) {
+    char* ptr = line;
 
-        char* ptr = line;
-        // skip leading whitespace
-        while(*ptr ==  ' ' || *ptr == '\t'){
-            ptr++;
-        }
-        // skip first field until reached whitespace or end of line
-        while (*ptr != '\0' && *ptr != ' ' && *ptr != '\t' ){
-            ptr++;
-        }
-        // skip whitespace between first field and rest
-        while(*ptr == ' ' || *ptr == '\t'){
-            ptr++;
-        }
-        return ptr;
+    // skip whitespace
+    while (*ptr == ' ' || *ptr == '\t') {
+        ptr++;
     }
 
-    void terminate_first_field(char* line){
-    	char* ptr = line;
-
-		// skip whitespace
-    	while (*ptr == ' ' || *ptr == '\t'){
-    		ptr++;
-    	}
-
-    	// get the end of the first word
-    	while (*ptr != '\0' && *ptr != ' ' && *ptr != '\n' && *ptr != '\t'){
-    		ptr++;
-    	}
-    	// terminate first word
-    	if(*ptr != '\0'){
-    		*ptr = '\0';
-    	}
+    // get the end of the first word
+    while (*ptr != '\0' && *ptr != ' ' && *ptr != '\n' && *ptr != '\t') {
+        ptr++;
+    }
+    // terminate first word
+    if(*ptr != '\0') {
+        *ptr = '\0';
     }
+}
 
-    /**
-     * Reads lines from a file into the provided array
-     * Returns the number of lines successfully read
-     */
-    int read_file_lines(char* filename, char lines[][256], int max_count) {
-        int file = open(filename, 0); // 0 = O_RDONLY
-        struct stat st; // stat struct contains a member called size, which holds the file's size in bytes
-        
-        if (file < 0) {
-            close(file);
-            return 0;
-        }
+/**
+ * Reads lines from a file into the provided array
+ * Returns the number of lines successfully read
+ * Returns 0 if file cannot be opened
+ * Returns -1 if metadata cannot be retrieved
+ * Returns -2 if file is empty
+ */
+int read_file_lines(char* filename, char lines[][256], int max_count) {
+    int file = open(filename, 0); // 0 = O_RDONLY
+    struct stat st; // stat struct contains a member called size, which holds the file's size in bytes
+    
+    if (file < 0) {
+        close(file);
+        return 0;
+    }
 
-        if (fstat(file, &st) < 0) { //check metadata
-            close(file);
-            return -1;
-        }
+    if (fstat(file, &st) < 0) { //check metadata
+        close(file);
+        return -1;
+    }
 
-        if (st.size == 0) { //check size to see if empty txt or not, join does not work if any or both files empty
-            close(file);
-            return -2;
-        }
-        
-        int line_count = 0;
-        char buffer[256];
-        int pos = 0;
-        char c;
-        
-        while (line_count < max_count && read(file, &c, 1) > 0) {
-            if (c == '\n') {
-                // End of line found
-                buffer[pos] = '\0';
-                
-                // Copy the line to the array
-                int i = 0;
-                while (i < 255 && buffer[i] != '\0') {
-                    lines[line_count][i] = buffer[i];
-                    i++;
-                }
-                lines[line_count][i] = '\0';
-                
-                line_count++;
-                pos = 0; // Reset position for next line
-            } else if (pos < 255) {
-                // Add character to buffer
-                buffer[pos] = c;
-                pos++;
-            }
-        }
-     
-        // Handle the last line if file doesn't end with newline
-        if (pos > 0 && line_count < max_count) {
+    if (st.size == 0) { //check size to see if empty txt or not, join does not work if any or both files empty
+        close(file);
+        return -2;
+    }
+    
+    int line_count = 0;
+    char buffer[256];
+    int pos = 0;
+    char c;
+    
+    while (line_count < max_count && read(file, &c, 1) > 0) {
+        if (c == '\n') {
+            // End of line found
             buffer[pos] = '\0';
+            
+            // Copy the line to the array
             int i = 0;
             while (i < 255 && buffer[i] != '\0') {
                 lines[line_count][i] = buffer[i];
                 i++;
             }
             lines[line_count][i] = '\0';
+            
             line_count++;
+            pos = 0; // Reset position for next line
+        } else if (pos < 255) {
+            // Add character to buffer
+            buffer[pos] = c;
+            pos++;
         }
-        
-        close(file);
-        return line_count;
     }
-
-    /**
-         * function prints joined line 
-         * "first word" "rest line file 1" "rest line file 2"
-        */
-        void print_joined_line(int output_file, char* field, char* rest1, char* rest2) {
-            printf("%s %s %s\n", field, rest1, rest2);
-
-			// check if there is a valid file descriptor
-			if (output_file >= 0) {
-            	// Write to the file 
-           		write(output_file, field, strlen(field));
-           		write(output_file, " ", 1);
-            	write(output_file, rest1, strlen(rest1));
-            	write(output_file, " ", 1);
-            	write(output_file, rest2, strlen(rest2));
-            	write(output_file, "\n", 1);
-            }
-      }
+ 
+    // Handle the last line if file doesn't end with newline
+    if (pos > 0 && line_count < max_count) {
+        buffer[pos] = '\0';
+        int i = 0;
+        while (i < 255 && buffer[i] != '\0') {
+            lines[line_count][i] = buffer[i];
+            i++;
+        }
+        lines[line_count][i] = '\0';
+        line_count++;
+    }
     
-    /**
-     * Compares lines from both files and looks for matches in the 
-     * first field
-     * If the fields match then print joined line
-    */
-    void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file) {
-        int matches_found = 0; 		// count for amount of matches found
-        int output_fd = -1;			// value of file descriptor of output file (-1 no valid file)
-
-        // Open the output file for writing (create it if it doesn't exist)
-        if(output_file != 0) {
-            // changes the value of output_fd to indicate we have a valid file
-            output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC); 	// open file with flags (create new file if it does not exist | 
-            														      	//	write access only | empty file if already exists)
-            if (output_fd < 0) {
-                printf("Error: Cannot open output file '%s'\n", output_file);
-                return;
-            }
+    close(file);
+    return line_count;
+}
+
+/**
+ * function prints joined line 
+ * "first word" "rest line file 1" "rest line file 2"
+*/
+void print_joined_line(int output_file, char* field, char* rest1, char* rest2) {
+    printf("%s %s %s\n", field, rest1, rest2);
+
+    // check if there is a valid file descriptor
+    if (output_file >= 0) {
+        // Write to the file 
+        write(output_file, field, strlen(field));
+        write(output_file, " ", 1);
+        write(output_file, rest1, strlen(rest1));
+        write(output_file, " ", 1);
+        write(output_file, rest2, strlen(rest2));
+        write(output_file, "\n", 1);
+    }
+}
+
+/**
+ * Compares lines from both files and looks for matches in the 
+ * first field
+ * If the fields match then print joined line
+*/
+void join_files(char file1_lines[][256], int count1, char file2_lines[][256], int count2, const char* output_file) {
+    int matches_found = 0;      // count for amount of matches found
+    int output_fd = -1;         // value of file descriptor of output file (-1 no valid file)
+
+    // Open the output file for writing (create it if it doesn't exist)
+    if(output_file != 0) {
+        // changes the value of output_fd to indicate we have a valid file
+        output_fd = open(output_file, O_CREATE | O_WRONLY | O_TRUNC);  // open file with flags (create new file if it does not exist | 
+                                                                       //  write access only | empty file if already exists)
+        if (output_fd < 0) {
+            printf("Error: Cannot open output file '%s'\n", output_file);
+            return;
+        }
+    }
+
+    // iterate through each line from file 1 
+    for (int i = 0; i < count1; i++) {
+        char line1_copy[256]; // make copy to avoid messing with original
+        int k = 0;
+
+        // string copy
+        while (k < 255 && file1_lines[i][k] != '\0') {
+            line1_copy[k] = file1_lines[i][k];
+            k++;
+        }
+        line1_copy[k] = '\0';
+        
+        char* field1 = get_first_field(line1_copy); // reads full line but only gets first word to check for match
+        // skip is field is empty 
+        if(field1 == 0) {
+            continue;
         }
 
-        // iterate through each line from file 1 
-        for (int i =0; i< count1; i++) {
-            char line1_copy[256]; // make copy to avoid messing with original
-            int k = 0;
+        terminate_first_field(field1); // get rid of first word to make comparing easier
+
+        // iterate through lines in file two 
+        for (int j = 0; j < count2; j++) {
+            char line2_copy[256]; // make copy to avoid messing with original
+            int m = 0;
 
             // string copy
-            while (k<255 && file1_lines[i][k] != '\0') {
-                line1_copy[k] = file1_lines[i][k];
-                k++;
+            while (m < 255 && file2_files[j][m] != '\0') {
+                line2_copy[m] = file2_lines[j][m];
+                m++;
             }
-            line1_copy[k] = '\0';
-            
-            char* field1 = get_first_field(line1_copy); // reads full line but only gets first word to check for match
-            // skip is field is empty 
-            if(field1 == 0) {
+            line2_copy[m] = '\0';
+                        
+            char* field2 = get_first_field(line2_copy); // read full line but only gets first word
+            // skip if field is empty
+            if(field2 == 0) {
                 continue;
             }
+            terminate_first_field(field2); // get rid of first word to make comparing easier
 
-            terminate_first_field(field1); // get rid of first word to make comparing easier
-
-            // iterate through lines in file two 
-            for (int j =0; j < count2; j++) {
-                char line2_copy[256]; // make copy to avoid messing with original
-                int m = 0;
-
-                // string copy
-                while (m<255 && file2_lines[j][m] != '\0') {
-                    line2_copy[m] = file2_lines[j][m];
-                    m++;
-                }
-                line2_copy[m] = '\0';
-                            
-                char* field2 = get_first_field(line2_copy); // read full line but only gets first word
-                // skip if field is empty
-                if(field2 == 0) {
-                    continue;
-                }
-                terminate_first_field(field2); // get rid of first word to make comparing easier
-
-                // check if both words are equal returns 0 if true
-                if(compare_strings(field1, field2) == 0) {
-                    matches_found++;
-                
-                    // get rest of lines for both files from where we got field
-                    char* rest1 = get_rest_of_line(file1_lines[i]);
-                    char* rest2 = get_rest_of_line(file2_lines[j]);
-
-					// print using format
-                    print_joined_line(output_fd, field1, rest1, rest2);
-
-                }
-            }                
-        }
-        // print message if no matches were found
-        if(matches_found == 0) {
-            printf("No matches found\n");
-        }
-        // Close the output file
-        close(output_fd);
+            // check if both words are equal returns 0 if true
+            if(compare_strings(field1, field2) == 0) {
+                matches_found++;
+            
+                // get rest of lines for both files from where we got field
+                char* rest1 = get_rest_of_line(file1_lines[i]);
+                char* rest2 = get_rest_of_line(file2_lines[j]);
+
+                // print using format
+                print_joined_line(output_fd, field1, rest1, rest2);
+            }
+        }                
+    }
+    
+    // print message if no matches were found
+    if(matches_found == 0) {
+        printf("No matches found\n");
     }
+    
+    // Close the output file
+    close(output_fd);
+}
+
+void print_usage() {
+    printf("Usage: join file1.txt file2.txt [outputfile.txt]\n");
+    printf("\nDescription:\n");
+    printf("  Joins two files based on matching first fields in each line.\n");
+    printf("  Output format: <matching_field> <rest_of_line1> <rest_of_line2>\n");
+    printf("\nArguments:\n");
+    printf("  file1.txt       First input file\n");
+    printf("  file2.txt       Second input file\n");
+    printf("  outputfile.txt  (Optional) Output file for results\n");
+    printf("\nOptions:\n");
+    printf("  --help          Display this help message\n");
+}
 
 int main(int argc, char *argv[]) {
-	// no output file before join
-	char* output_file = 0; 
-    // ensure correct usage of command line args
+    // Handle --help flag
+    if (argc == 2 && compare_strings(argv[1], "--help") == 0) {
+        print_usage();
+        exit(0);
+    }
+
+    char* output_file = 0;
+    
+    // Validate command line arguments
     if (argc == 4) {
-    	output_file = argv[3];
-    	printf("Joining files '%s' and '%s' -> output to '%s'...\n", argv[1], argv[2], argv[3]);
-	} else if (argc == 3) {
-		printf("Joining files '%s' and '%s'...\n", argv[1], argv[2]);
-	} else {
-        printf("Usage: join file1.txt file2.txt [outputfile.txt]\n");
+        output_file = argv[3];
+    } else if (argc != 3) {
+        print_usage();
         exit(1);
     }
 
-    // read both files
-    printf("Attempting to read first file...\n");
+    // Read both files
     int count1 = read_file_lines(argv[1], file1_lines, 50);
-    if(count1 == 0) {
-    	printf("ERROR: failed to read lines from %s\n", argv[1]);
-    	exit(1);
-    } else if(count1 == -1) {
-        printf("ERROR: failed to retrive metadata from %s\n", argv[1]);
-        exit(1);
-    } else if(count1 == -2) {
-        printf("ERROR: %s is empty\n", argv[1]);
+    if(count1 <= 0) {
+        if(count1 == 0) {
+            printf("ERROR: failed to open %s\n", argv[1]);
+        } else if(count1 == -1) {
+            printf("ERROR: failed to retrieve metadata from %s\n", argv[1]);
+        } else if(count1 == -2) {
+            printf("ERROR: %s is empty\n", argv[1]);
+        }
+        print_usage();
         exit(1);
-    } else {
-        printf("File %s exists\n", argv[1]);
-        printf("Read %d lines from file 1\n", count1);
     }
     
-    printf("Attempting to read second file...\n");
     int count2 = read_file_lines(argv[2], file2_lines, 50);
-    if(count2 == 0) {
-    	printf("ERROR: failed to read lines from %s\n", argv[2]);
-    	exit(1);
-    } else if(count2 == -1) {
-        printf("ERROR: failed to retrive metadata from %s\n", argv[2]);
-        exit(1);
-    } else if(count2 == -2) {
-        printf("ERROR: %s is empty\n", argv[2]);
+    if(count2 <= 0) {
+        if(count2 == 0) {
+            printf("ERROR: failed to open %s\n", argv[2]);
+        } else if(count2 == -1) {
+            printf("ERROR: failed to retrieve metadata from %s\n", argv[2]);
+        } else if(count2 == -2) {
+            printf("ERROR: %s is empty\n", argv[2]);
+        }
+        print_usage();
         exit(1);
-    } else {
-        printf("File %s exists\n", argv[2]);
-        printf("Read %d lines from file 2\n", count2);
     }
     
-    // join both files
-    printf("joining both files\n");
-    // call function that joins files into output file
+    // Join both files
     join_files(file1_lines, count1, file2_lines, count2, output_file);
     if(output_file != 0) {
-    	printf("Output saved to %s\n", output_file);
+        printf("Output saved to %s\n", output_file);
     }
     
     printf("join completed\n");
-
+    
     exit(0);
 }

From c83b01093ff8a9982d638eee1ec3d79176af9bec Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Mon, 6 Oct 2025 04:45:36 -0700
Subject: [PATCH 23/24] Correcting test folder name

---
 docs/Documentation.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/docs/Documentation.md b/docs/Documentation.md
index 10193f0..4df007c 100644
--- a/docs/Documentation.md
+++ b/docs/Documentation.md
@@ -14,7 +14,7 @@ make
 This will:
 - Compile the kernel from source files in the `kernel/` directory
 - Compile user programs from the `user/` directory
-- Copy test data files from `testData/` to the root directory
+- Copy test data files from `tests/` to the root directory
 - Create the filesystem image (`fs.img`) containing all programs and data files
 
 ## Running the Software
@@ -99,13 +99,13 @@ This removes:
 - Compiled object files (*.o)
 - Kernel binary and filesystem image
 - Temporary files
-- Test data files copied to root (preserves originals in `testData/`)
+- Test data files copied to root (preserves originals in `tests/`)
 - Note: `compile_flags.txt` in root is preserved
 
 ## Project Structure
 
 - `kernel/` - Operating system kernel source code
 - `user/` - User-space programs and utilities
-- `testData/` - Original test data files (preserved during clean)
+- `tests/` - Original test data files (preserved during clean)
 - `mkfs/` - Filesystem creation utility
 - `Makefile` - Build configuration and targets

From a49742500a41eb07531a18d0ac9bae7b82e610b3 Mon Sep 17 00:00:00 2001
From: DEMETRIUS CHATTERJEE <dchatterjee3@dons.usfca.edu>
Date: Mon, 6 Oct 2025 05:01:20 -0700
Subject: [PATCH 24/24] Simplied user feedback when storing results to a file

---
 user/join.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/user/join.c b/user/join.c
index 7ccb79a..a53d34b 100644
--- a/user/join.c
+++ b/user/join.c
@@ -179,8 +179,11 @@ int read_file_lines(char* filename, char lines[][256], int max_count) {
  * "first word" "rest line file 1" "rest line file 2"
 */
 void print_joined_line(int output_file, char* field, char* rest1, char* rest2) {
-    printf("%s %s %s\n", field, rest1, rest2);
-
+    // Only print to console if NOT writing to a file
+    if (output_file < 0) {
+        printf("%s %s %s\n", field, rest1, rest2);
+    }
+    
     // check if there is a valid file descriptor
     if (output_file >= 0) {
         // Write to the file 
@@ -239,7 +242,7 @@ void join_files(char file1_lines[][256], int count1, char file2_lines[][256], in
             int m = 0;
 
             // string copy
-            while (m < 255 && file2_files[j][m] != '\0') {
+            while (m < 255 && file2_lines[j][m] != '\0') {
                 line2_copy[m] = file2_lines[j][m];
                 m++;
             }