C Programming Language • Process Management • File Descriptors and Redirections • Exhaustive Parsing • Signal Handling • Error Management • Memory Management • Norm Compliance • Compilation Automation with Makefile

Minishell

This project is about creating a little bash to learn about processes and file descriptors.

Key	Value
Program name	minishell
Language	C
Turn in files	Makefile, *.h, *.c
Makefile	NAME, all, clean, fclean, re
External functs.	readline, rl_clear_history, rl_on_new_line, rl_replace_line, rl_redisplay, add_history, printf, malloc, free, write, access, open, read, close, fork, wait, waitpid, wait3, wait4, signal, sigaction, sigemptyset, sigaddset, kill, exit, getcwd, chdir, stat, lstat, fstat, unlink, execve, dup, dup2, pipe, opendir, readdir, closedir, strerror, perror, isatty, ttyname, ttyslot, ioctl, getenv, tcsetattr, tcgetattr, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs

Handled Bash POSIX features:

• Display a prompt when waiting for a new command.
• Have a working history.
• Search and launch the right executable (based on the PATH variable or using a relative or an absolute path).
• No use of more than one global variable (to indicate a received signal). This approach ensures that the signal handler will not access the main data structures.
• ’ (single quote) which prevent the shell from interpreting the metacharacters in the quoted sequence.
• " (double quote) which prevent the shell from interpreting the metacharacters in the quoted sequence except for $ (dollar sign).
• Redirections:
  • < redirects input.
  • > redirects output.
  • << heredoc: redirects input from a string following the command.
  • >> redirects output in append mode.
• | (pipe character). The output of each command in the pipeline is connected to the input of the next command via a pipe.
• $: Environment variables ($ followed by a sequence of characters which should expand to their values).
• $? which should expand to the exit status of the most recently executed foreground pipeline.
• In interactive mode:
  • ctrl-C displays a new prompt on a new line.
  • ctrl-D exits the shell.
  • ctrl-\ does nothing.
• The following builtins:
  • echo with option -n
  • cd with only a relative or absolute path
  • pwd with no options
  • export with no options
  • unset with no options
  • env with no options or arguments
  • exit with no options

The readline() function can cause memory leaks, but none of the leaks are reachable outside of the readline() library itself.

Usage

git clone git@github.com:nfauconn/minishell.git
cd minishell/Project
make

./minishell