MyShell/UserManual.txt at master · AyushYadav/MyShell · GitHub

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NAME
	myshell - a simple shell with its own internal commands for the CS 307 assignment #2

SYNOPSIS
	myshell [batch_file]

DESCRIPTION
	myshell is a simple shell implementation with support for cd, clr, dir, environ, echo, help, pause
	and quit commands as well as basic input and output redirection. It includes a command line for
	entering single commands with their appropriate arguments as well as support for a file with a list
	of commands (batchfile) to be called when myshell is first ran. This manual describes the implementation
	of these commands, how they work and what they do.


COMMANDS

	cd <directory>: Stands for 'change directory' to the directory specified. If no directory is specified
					e.g. 'cd' by itself, then cd will return the current working directory path instead of
					changing the directory. If the directory specified does not exist, an error message
					will be presented to the user.

					NOTE: cd will change the environment paths, specifically the PWD environment variable.
					This is described in more detail in the ENVIRONMENT section.

					Command formats:
					cd : returns current working path
					cd <directory> : changes current working directory to directory specified. Returns error
					if directory does not exists.

	clr : Clears the screen of all text, so that only the prompt is visible.
					Command formats:
					clr : clear command takes in no arguments


	dir <directory> : Stands for 'directory' and lists the contents of the directory specified.
					contents are listed as one in each line. The same as calling 'ls -la' command in other shells.

					Command formats examples:
					dir : Contents of current directory are listed.
					dir <directory> : contents of specified directory are listed.


	environ : environ command lists all the environment strings. This includes special environment strings
					shell and parent. More information in the ENVIRONMENT section. It takes no arguments and supports
					output redirection.

					Command format example:
					environ : environment string variables printed out on command prompt.


	echo <comment> : echo command prints out the text inputted after the echo command, followed by a newline character.
					Command format examples:
					echo hi there : print out "hi there" on the command line


	help : displays the user manual  to display contents in readable blocks explaining various usage of the commands in myshell.


	pause : pauses the operation of myshell until 'enter' is pressed


	quit : quit closes the shell as ctrl-c (SIGINT) kill signal is caught by myshell


ENVIRONMENT:

	The environment is an array of character pointers specifying the string variables relating to the
	current working environment of myshell. Environment variables hold information like the location
	of the myshell program and path of current working directory. myshell inherits all the processes
	from which it was invoked. However it does specify the following environment variables.

	parent : parent path variable is the shell variable inherited by all child processes after forking.

	shell : is the full path for the myshell executable. I.e. not a hardwired path but the one from which
	it was executed.

	PWD : stands for present working directory, which is changed upon each successful directory change.


***************************************************************************************************************
-----------Manual for myshell, last updated 4th of September, 2015 by Ayush Yadav and Samriddhi Jain.----------
***************************************************************************************************************