b.sh

(best shell)

Description

A simple UNIX command interpreter.

• Displays a prompt and waits for the user to type a command. Command line always ends with a new line.
• The prompt is displayed again each time a command has been executed.
• The command lines are simple, no semi-columns, no pipes, no redirections or any other advanced features.
• If an executable cannot be found, prints an error message and displays the prompt again.
• Handles errors.
• Handles the “end of file” condition (Ctrl+D).
• Handles command lines with arguments.
• Handles the PATH.
• Implements the exit buit-in, that exits the shell (Usage: exit).
• Implements the env built-in, that prints the current environment.

Files

Files	Description
main.c	main shell entry and loop
shell_instance.c	starts shell, recieves and interprets user input
bundled_funcs.c	display custom prompt and get absolute path
utils.c	obtain string tokens and execute files
helpers.c	functions that help obtain a programs path and tokenize strings
built_in.c	checks for and runs builtin functions
shell.h	header file: contains prototypes, libraries and macros

Examples

Prompt

B.SH | Raid55@vagrant:/home/vagrant/simple_shell$

ls -l

B.SH | Raid55@vagrant:/home/vagrant/simple_shell$ ls -la
total 68
drwxrwxr-x  3 vagrant vagrant  4096 Nov 21 05:23 .
drwxr-xr-x 11 vagrant vagrant  4096 Nov 21 05:21 ..
drwxrwxr-x  8 vagrant vagrant  4096 Nov 21 05:22 .git
-rw-rw-r--  1 vagrant vagrant   430 Nov 21 02:46 .gitignore
-rw-rw-r--  1 vagrant vagrant  3533 Nov 21 05:21 README.md
...

Exit

B.SH | Raid55@vagrant:/home/vagrant/simple_shell$ exit
vagrant@vagrant-ubuntu-trusty-64:~/simple_shell$

Requirements

• Allowed editors: vi, vim, emacs
• All files will be compiled on Ubuntu 14.04 LTS
• Programs and functions will be compiled with gcc 4.8.4 using the flats -Wall -Werror -Wextra and -pedantic
• All files should end with a new line
• Code should use the Betty style. it will be checked using betty-style.pl and betty-doc.pl
• Not allowed to use global variables
• No more than 5 functions per file
• The prototypes of all functions should be included in the header file called holberton.h
• All header files should be include guarded
• Authorized functions and system calls:
  • access (man 2 access)
  • chdir (man 2 chdir)
  • close (man 2 close)
  • closedir (man 3 closedir)
  • execve (man 2 execve```)
  • exit (man 3 exit)
  • fork (man 2 fork)
  • free (man 3 free)
  • stat (man 2 stat)
  • lstat (man 2 lstat)
  • fstat (man 2 fstat)
  • getcwd (man 3 getcwd)
  • getline (man 3 getline)
  • kill (man 2 kill)
  • malloc (man 3 malloc)
  • open (man 2 open)
  • opendir (man 3 opendir)
  • perror (man 3 perror)
  • read (man 2 read)
  • readdir (man 3 readdir)
  • signal (man 2 signal)
  • strtok (man 3 strtok)
  • wait (man 2 wait)
  • waitpid (man 2 waitpid)
  • wait3 (man 2 wait3)
  • wait4 (man 2 wait4)
  • write (man 2 write)
  • _exit (man 2 _exit)
  • isatty (man 3 isatty)
  • fflush (man 3 fflush)

Notes

Tested on Ubuntu 14.04 LTS. No known bugs.

Author

• James Heck
• Raid55 (Nick B.)