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  • 0️⃣ Rank 00
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  • 1️⃣ Rank 01
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  • 2️⃣ Rank 02
    • so_long
      • ▪️Understand so_long
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      • ▪️Understand pipex
      • ▪️Functions used
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    • minitalk
      • ▪️Understand minitalk
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    • push_swap
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      • 🗡️Understand FdF
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  • 3️⃣ RANK 03
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      • ▪️Understand Philosophers
      • ▪️Functions used
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      • ▪️Understand Minishell
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  • 4️⃣ RANK 04
    • CPP (00 - 04) (doing)
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  • 5️⃣ RANK 05
    • CPP (05-09) (to-do)
      • CPP05
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  • 6️⃣ rank 06
    • ft_transcendence (to-do)
  • 🛂Exams
    • Exam Rank 02
      • Level 1
        • first_word
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      • Level 2
        • alpha_mirror
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        • ft_strrev
        • inter
        • last_word
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      • Level 3
        • add_prime_sum
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        • rstr_capitalizer
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      • Level 4
        • flood_fil
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    • Exam Rank 03
    • Exam Rank 04
    • Exam Rank 05
      • Module 0
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  1. Exams

Exam Rank 04

Minihell part 2 (oh nooo again ?!)

The Rank 4 exam of 42 is quite simple: just recreate a micro shell.

Subject

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.

Example that should work :

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

>./microshell 

One solution (that inspired me)
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Last updated 1 year ago

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🛂
https://github.com/shackbei/microshell-42/blob/main/microshell.c