sub shell

Definition

A subshell is basically a new shell just to run a desired program. A subshell can access the global variables set by the 'parent shell' but not the local variables. Any changes made by a subshell to a global variable is not passed to the parent shell.
Source

Parent - and child process

A child process in computing is a process created by another process (the parent process). This technique pertains to multitasking operating systems, and is sometimes called a subprocess or traditionally a subtask.
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