SHELL

A simple shell written completely in C ,using system calls and function libraries . The shell can be used for redirection and piping ( | , > , < , >>)

Install and Run

Installation :

git clone https://github.com/SubbulakshmiRS/Shell

Compile and Run :

make

./a.out

Clean the files :

make clean

Commands

The commands which have been implemented are from scratch are :

cd

ls (flags -l,-a)

Ctrl+C

Ctrl+Z

pwd

echo

Personal commands have also been implemented :

clock -t

This command prints every n seconds (argument ) the system local time .This operation will stop by Ctrl+C . example: clock -t 3 - every 3 seconds

remindme

This command prints a reminder (statement is an argument) after n seconds (argument) .This is a background process . example: remindme 10 hello - this prints "hello" after 20 seconds .

pinfo

This command prints the information of any process whose pid is passed . If no number is passed , then the process information of the running base shell is printed out . example: pinfo

setenv

Can create or overwrite values of environment variables of the shell example: setenv NUKE_PATH /SharedDisk/Nuke/

unsetenv

Can unset any environment variable . example: unsetenv NUKE_PATH

jobs

Prints out all the current / forcefully stopped jobs with their process id . example: jobs

kjob

can send specific signals to jobs having the given number as shown with the above command(jobs). example: kjob 2 9

fg

brings a running or a stopped background job with given job number to foreground. example: fg 1

bg

changes a stopped background job to a running background job. example: bg 1

overkill

kills all background process at once. example: overkill

quit / exit()

exits out of the shell example: quit / exit()

Files

Makefile

For creating the object files and executables . Also for deleting unneccessary files by make clean .

main.h

Header file containing all function declarations and global variables .

shell.c

The main file containing all the inputs

args.c

Contains all functions for the taking inputs and turning into tokens.

commands.c

Contains the code for calling all functions for executing the built-in commands

directory.c

Contains function for changing directories and making a list of all files in that folder

stat_ls.c

Contains the code for collecting and printing out all the information for all files like the bash -"ls -l " - command .

time_file.c

Contains the functions for getting the system local time .

pinfo_data.c

For a given pid , all information from the system files are given about the process .By default the pid is that of the base parent process (shell).

bg_check.c

Contains the commands to check and print the condition of all background processes

signal_handle.c

Contains the functions for handling SIGCHLD , SIGINT and SIGSTOP signals .

store.c

Functions for storing details about current or force-stopped background processes . (for jobs command)