InteractiveShell

• An interactive user defined shell in C

Complile

• Complile using "make"
• Recompile : delete all .o file by make clean and then again do make.

Run

• Run using ./shell

Features

General

• Works almost like normal shell
• Coloured prompt
• Keeps the directory where the shell is run, as home directory and shows the path of the current directory relative to that home directory
• Every command is run in new forked process
• Error Handling

Background Processes

• Commands which have '&' appended, run in background
• When background process exits, shell display a message with its exit status

Implemented Built-in-Commands

These commands are implemented as a part of shell

• cd (Also "cd -" )
• echo
• pwd
• ls (ls -l, ls -al, ls -a, ls -la with directory name )
• setenv var [value]
• unsetenv var
• jobs
• kjob
• fg
• bg
• overkill
• quit
• CTRL-Z
• CTRL-C
• pinfo
  • It returns process related information like pid, process status, memory, etc

For Assignment 3

Specification 1: Foreground and background processes

1. If the background process exits then the shell will display the appropriate message to

   the user and for foreground process shell will wait and regain its control once the process exist.

   ​

Specification 2: Implement input-output redirection functionality

1. Output of running one (or more) commands can be redirected to a file.

Specification 3: Implement command redirection using pipes

1. Program can handle any number of pipes.

   ​

Specification 4: Implement i/o redirection + pipes redirection

• Use Case : Example => cat < in.txt | wc -l > lines.txt

Specification 5: User-defined commands

• listed in Builtins Command

BONUS

1. If the background process exits then the shell must display the appropriate message to the user.
2. nightswatch (interrupt,dirty)

• Non blocking user input method if User press 'q' then exit
• [ nightwatch -n t interrupt] It print the number of times the CPU(s) has(ve) been interrupted by the keyboard controller (i8042 with IRQ 1) t times on screen .
• [ nightwatch -n t dirty] It prints the total amount of memory, in kilobytes, waiting to be written back to the disk on every t seconds.

File Structure

Modularity in Code

src directory

• Makefile
  • Compile and link all file and made a executable file ./shell to run shell
• main.c
  • Main file where shell is running and prompt is displaying
• read_and_parse.c
  • Read user command and parse it i.e tokenise it.
• check_background_process.c
  • Check if a process to be run in background
• launcher.c
  • Launch the prepared execute instruction
• execute.c
  • Preparing to execute the instruction
• filename.h
  • containing respective libraries nedded
• redirection.h
  • containing respective libraries nedded
• redirection.c
  • Execute redirection command
• piping.h
  • containing respective libraries nedded
• piping.c
  • Execute and handle number of pipes

builtins directory [Name of file showing function it performs]

* cd.c
* echo.c
* ls.c
* exit_quit.c
* pinfo.c
* pwd.c
* nightswatch.c
* setenv_unsetenv.c
* jobs.c
* fg_bg.c
* kjob.c
* overkill.c
* builtin_func.h

Devlopers

Gulshan Kumar  Aman Bansal

Licensing

Copyright (C) - All Rights Reserved Unauthorized copying of this file, via any medium is strictly prohibited