Make command in the terminal creates the a.out executable file for running the shell

ls

• Lists the contents of the given directory.
• Add -l to display the details of each file.
• Add -a to display the hidden contents.
• The directories and flags can be mentioned in any order after ls

; separated commands

• You can run more than 1 shell command in a single line by separating them with a ;

cd

• change the current working directory to the relative or the absolute path passed as argument.
• ~ to go back to the shell executable directory.
• .. to go to the previous directory.
• - will change your directory to the previous directory you were in.
• no arguements passed change the directory to home directory.

pwd

• To see the present working directory pwd.

pinfo

• Displays the process information.
  • Process ID
  • Process Status
  • Virtual memory
  • executable path.
• If the PID is not mentioned it will show the information about the shell process.

History

• Displays the last used commands with most recent ones appearing at the bottom of the list.
• stores uptill 20 history commands.

File redirection

• < is used for input redirection. cat < input File contents of input are redirected to stdin and cat is executed.
• > is used for output redirection. ls > output the output of ls is redirected to output file.
• Both of them can be combined together in a single command.

Piping

• | Can be used to redirect one commands output to another file. ls | wc Will redirect the output of ls to wc.
• More than 2 commands can be chained together for piping.

Environment variables

• setenv can be used to overwrite the value of a environment variable to the given value.
• unsetenv can be used to remove the variable from the environment.

Jobs

• Jobs are processes spawned by the shell, jobs will list the processes spawned by the shell along with their status and the pid.
• kjob job_number signal_number Will send the signal to the given job.
• overkill Will kill all background processes at once.
• exit Will exit out of the shell.

Signal handling

• Ctrl+Z will kill send the current foreground process to the background and will stop the process.
• Ctrl+C will interrupt the currently running foreground process, if no foreground process is present, it will do nothing.

fg/bg [Incomplete]

• fg can be used to bring a background process to the foreground process. The shell will only continue to execute after the process has terminated.
• bg can be used to make a stopped background process run again.

File Wise Details

main.c:

• Shell implementation
• Signal handler

headers.h:

• All the headers required are inserted here it self

functions.h

• All the global variables and functions are ideclared here

functions.c:

• string tokeninizig function
• cd , pinfo, echo implementations
• setenv,unsetenv,jobs,kjob has been implemneted
• fg and bg , overkill, quit

ls.c:

• whole ls implementation has been done here

history.c:

• History recording and history command implementation has been coded here
• History command implementation is acheived through creating a txt file where the executable file is running, it is modified every time when a command given to the terminal.

Other details:

• If & is given with builtin commands like(ls &, cd &, pid &,...), they have been assumed as foreground ....

• ctrl-z,ctrl-c has been handled by creating handlers

• last working directory is achieved through storing cwd after implentation of command.