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This file is a manual page for our simple Unix command line interpreter.

• Allowed editors: vi, vim, emacs
• All files will be compiled on Ubuntu 14.04 LTS
• The C programs and functions will be compiled with gcc 4.8.4 using the flags -Wall -Werror -Wextra and -pedantic
• The code uses the Betty style. It will be checked using betty-style.pl and betty-doc.pl.
• There will be no more than 5 functions per file, and each file should end in a newline.
• All header files should be include guarded
• Only use system calls when necessary

• Unless specified, our program should have the exact same output as sh (/bin/sh) as well as the exact same error output. The only difference is when we print an error, the name of the program will be equivalent to our argv[0] (see below)

Example of error with sh:

$ echo "qwerty" | /bin/sh
/bin/sh: 1: qwerty: not found
$ echo "qwerty" | /bin/../bin/sh
/bin/../bin/sh: 1: qwerty: not found

Same error with our program hsh:

$ echo "qwerty" | /bin/hsh
/bin/sh: 1: qwerty: not found
$ echo "qwerty" | ./././hsh
./././hsh: 1: qwerty: not found

• 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)

The shell should be compiled in this way:

gcc -Wall -Werror -Wextra -pedantic *.c -o hsh

Our shell should work like this in interactive mode:

$ ./hsh
($) /bin/ls
hsh main.c shell.c
($)
($) exit
$

But also in non-interactive mode:

$ echo "/bin/ls" | ./hsh
hsh main.c shell.c test_ls_2
$
$ cat test_ls_2
/bin/ls
/bin/ls
$
$ cat test_ls_2 | ./hsh
hsh main.c shell.c test_ls_2
hsh main.c shell.c test_ls_2
$

What our UNIX command line interpreter does:

• Display a prompt and wait for the user to type a command. A command line always ends with a new line.
• The command is displayed again each time a command has been executed.
• The command lines are simple, no semicolons, no pipes, no redirections or any other advanced features.
• The command lines are made only of one word.
• If an executable cannot be found, print an error message and display the prompt again.
• Handle errors.
• Handle the "end of file" condition (Control+D)
• Handle the PATH
• Take the command exit that exits the shell.
• Print current environment with env
• Change the current working directory cd
• Handle special characters: ", ', \, *, &, #, `

What our shell does not have to do:

• Be able to move the cursor.

Abdulrahman Khaled Github.

Fadi Haddad Github.