Microshell exam

Assignment name : microshell

Expected files : microshell.c

Allowed functions: malloc, free, write, close, fork, waitpid, signal, kill, exit, chdir, execve, dup, dup2, pipe, strcmp, strncmp

Write a program that will behave like executing a shell command

The command line to execute will be the arguments of this program
Executable's path will be absolute or relative but your program must not build a path (from the PATH variable for example)
You must implement "|" and ";" like in bash
- we will never try a "|" immediately followed or preceded by nothing or "|" or ";"
Your program must implement the built-in command cd only with a path as argument (no '-' or without parameters)
- if cd has the wrong number of argument your program should print in STDERR "error: cd: bad arguments" followed by a '\n'
- if cd failed your program should print in STDERR "error: cd: cannot change directory to path_to_change" followed by a '\n' with path_to_change replaced by the argument to cd
- a cd command will never be immediately followed or preceded by a "|"
You don't need to manage any type of wildcards (*, ~ etc...)
You don't need to manage environment variables ($BLA ...)
If a system call, except execve and chdir, returns an error your program should immediatly print "error: fatal" in STDERR followed by a '\n' and the program should exit
If execve failed you should print "error: cannot execute executable_that_failed" in STDERR followed by a '\n' with executable_that_failed replaced with the path of the failed executable (It should be the first argument of execve)
Your program should be able to manage more than hundreds of "|" even if we limit the number of "open files" to less than 30.

for example this should work:

$>./microshell /bin/ls "|" /usr/bin/grep microshell ";" /bin/echo i love my microshell
microshell
i love my microshell
$>

Hints: Don't forget to pass the environment variable to execve

Hints: Do not leak file descriptors!

xilen0x/42_microshell