Simple_Shell

Simple UNIX command line interpreter.

Requirements

General

• Editors: vi, vim, emacs.
• All files compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89
• All files end with a new line.
• Code use the Betty style. Checked using betty-style.pl and betty-doc.pl.
• Shell does not have any memory leaks.
• No more than 5 functions per file.
• All header files are include guarded.
• System calls used only when you needed.
• A README with the description of your project exist at the root of the folder of the project.
• An AUTHORS file at the root of your repository exist, listing all individuals having contributed content to the repository.

More Info

Output

• Program has the exact same output as sh (/bin/sh) as well as the exact same error output.
• The only difference is when you print an error, the name of the program must be equivalent to your 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 your program hsh:

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

compilation

gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o hsh

Testing

Our simple shell works 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
$

Tasks

0. Betty would be proud

• Our beautiful code passes the Betty checks
• Run betty * to verify

1. Simple shell 0.1 *UNIX command line interpreter.

Our Shell:

• Displays a prompt and wait for the user to type a command.
• A command line always ends with a new line.
• The prompt is displayed again each time a command has been executed.
• If an executable cannot be found, print an error message and display the prompt again.
• Handles errors.
• You have to handle the “end of file” condition (Ctrl+D).

2. Simple shell 0.2

• Simple shell 0.1 +

• Handles command lines with arguments

3. Simple shell 0.3

• Simple shell 0.2 +

• Handles the PATH
• fork is not be called if the command doesn’t exist

4. Simple shell 0.4

• Simple shell 0.3 +

• Implements the exit built-in, that exits the shell

5. Simple shell 1.0

• Simple shell 0.4 +

• Implements the env built-in, that prints the current environment