File System Navigation & Inspection

Navigation

• pwd “Print working director”
  Command display the file where I work.

• cd “change directory”
  command that allow to move between folders.

Listing & File Information

• ls “List”
  show files and directories.

Options of ls:

• -l shows the long format of files.

• -A shows the hidden files.

• -s shows files and directories along with their sizes.

• file
  Command that determines the type of file.

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Links

• ln “Link”
  Command creates links to files or directories.

Options of ln:

• -s creates a soft link.
• -f Force overwrite if the link already exists.
• -v shows what’s happening step by step
• -n don’t dereference soft link
• -t treat target as file

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File & Directory Operations

• cp “copy”
  Command that copy files or directors from one location to another.

Options of copy:

• -i prompts before overwriting an existing file.

• -r copies directories and their contents recursively.

• mv “move”
  command used to move or rename files and directories.

Options of mv:

• -i prompts before overwriting an existing file.

• -v Display detailed information about what the command is doing.

• rm “remove”
  Command that removes files and directories.

Options of rm:

• -i prompts before overwriting an existing file.

• -r Removes directories and their contents recursively.

• mkdir “make directory”
  Command that create a new directory or multiple directories.

• touch
  command used to make file

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File System Tree

Unix-like OS using hierarchical directory structure Method to organized flies.

• Root
  The First Folder in the tree.

• Current working directory
  the Folder that you are in.

• Parent directory
  each folder contains folders or files.

• Brach
  each folder or File inside folder.

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Permissions & Ownership

Types of files:

• Regular File -
  All files that contain data

• Directory d
  Folders

• Character device c
  A device that sends and receives data one piece at a time, like typing on a keyboard.

• Block device b
  A device that stores data and reads or writes it in large chunks, like a hard disk.

• Pipe p
  Allows communication between two processes, where the output of one process becomes the input of another.

• Socket s
  Are files used for communication between running programs to transfer data on the same device or over the network.

• Soft link l
  Command creates links to files or directories.

Types of Permission:

• Read r
  Reading files

• Write w
  Writing on file

• Execute x
  Executing the file

Grant to:

• User
• Group
• Public

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Permission Commands

• chmod
  command used to change permissions of files and directories.

• whoami
  command used to show the current user name.

• chown
  command used to change the owner of file or directory.

• chgrp
  used to change the owner group of a file or directory.

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Searching Files

• find
  Command used to search for files and directories based on various conditions within the filesystem in real time.

Options:

• -type
  match files based on their type

• -name
  match files and directories based on their name or a specified filename pattern.

• -size
  match files according to their size.

• -user
  match files owned by a specific user.

Actions:

• -exec
  Executes a command on each found file.

• -delete
  Deletes files found by find.

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Text Processing

• sort
  command used to sort command output or text file content.

Options:

• -r used to sort UP to Down.

• -o option used to save sorted output to a file.

• uniq
  command used to remove or filter duplicate lines from sorted text.

Options:

• -u option used to display only unique lines from sorted text.

• -c option used to count how many times each line appears in sorted text.

• comm
  command used to compare two sorted files line by line.

• diff
  command used to show differences between two files line by line.

• cut
  command used to extract specific columns or fields from text.

Options:

• -c used to select specific character positions from each line.
• -f option used to select specific fields from text separated by a delimiter.
• -d option used to specify the delimiter that separates fields in text.

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Bash Basics

Wildcard: symbols used to match multiple files or directories by pattern.

• * asterisk
• ? question mark
• [ ] sets
• [!] NOT in the specified set

Brace Expansion: matches patterns inside { } and expands them into multiple values.

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Streams & Pipes

Types of streams:

• Stdin 0

• Stdout 1

• Stderr 2

• | pipeline

• & Background Jobs