smallsh

Shell implementing a small subset of features of other well-known shells.

Compiling

With gcc:

gcc -Wall -std=c99 -g3 smallsh.c smallshutils.c smallshtok.c smallshcd.c smallshstatus.c smallshfgspawn.c smallshbgspawn.c smallshsig.c -o smallsh

Features

• Provides a prompt for running commands
• Handles blank lines and comments, which are lines beginning with the # character
• Provides expansion for the variable $$
• Executes 3 commands exit, cd, and status via code built into the shell
• Executes other commands by creating new processes using a function from the exec family of functions
• Supports input and output redirection
• Supports running commands in foreground and background processes
• Implements custom handler SIGINT
  • A child running as a foreground process must terminate itself when it receives SIGINT
  • Parent process ignores SIGINT
• Implements custom handler for SIGTSTP
  • A child, if any, running as a foreground process ignores SIGTSTP
  • Children running as background processes ignore SIGTSTP
  • Parent process receiving SIGSTP for the first time enters foreground only mode (no background processes allowed using & operator)
  • If the user sends SIGTSTP again, shell then returns back to the normal condition where the & operator is once again honored for subsequent commands

Sample Program Execution