MiniShell – Interactive Unix-like Shell

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Description

MiniShell (msh) is a minimalistic Unix-like shell implemented in C as part of the Linux Internal module.
It allows execution of built-in commands, external programs, background jobs, and supports signals, pipes, and job control.

The project helps in understanding system calls, process management, signal handling, and command parsing.

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Features

• Customizable prompt (PS1)
• Built-in commands: cd, pwd, exit
• Special variables:
  • $$ – PID of msh
  • $? – Exit status of last command
  • $SHELL – Shell executable path
• Background process support (&)
• Job control commands: jobs, fg, bg
• Signal handling: Ctrl+C (SIGINT), Ctrl+Z (SIGTSTP)
• Pipe functionality: Multiple processes communication (ls | wc, ls -l /dev | grep tty | wc -l)

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Installation

1. Clone the repository:

bash git clone [email protected]:SanjaiScript/-MiniShell-Interactive-Unix-like-Shell-.git

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Navigate to the project folder:

cd MiniShell-Interactive-Unix-like-Shell

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Compile the C files:

gcc *.c -o msh

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Usage

Run the shell: ./msh

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Sample commands inside MiniShell:

msh> pwd

msh> echo Hello World!

msh> ls -l | grep ".c"

msh> sleep 10 &

msh> jobs

msh> fg

msh> exit

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Change prompt:

PS1=NewPrompt>

Debug / Sample Output

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MiniShell> pwd /home/linux_engineer

MiniShell> ls -l -rw-r--r-- 1 user user 1024 Jan 12 12:00 main.c

MiniShell> sleep 10 & DEBUG: Created background process with PID 12345

MiniShell> jobs [1]+ 12345 Running sleep 10 &

MiniShell> fg Bringing PID 12345 to foreground

MiniShell> exit INFO: Exiting MiniShell. Goodbye!

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Author

Sanjai Kumar M @SanjaiScript