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exam04 의 microshell로 minishell의 기본 구조, pipe에 대한 아이디어를 얻을 수 있다는 소문을 듣고! microshell 공유합니다 :)

link : https://github.com/Glagan/42-exam-rank-04/blob/master/microshell/microshell.c

subject

Assignment name : microshell Expected files : *.c *.h 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!