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crash
============
crash is our implementation of the 42 common core project "minishell" in C89.
However unlike what the subject requires, we've built a fully posix compliant
shell.

crash stands for Can't Rest Again SHell which we (kind of derived) out of the
pain it is to implement a standard compliant shell.

using our shell
============
To compile crash, you'll need to have readline headers and the readline shared
library. Which you can install with your favorite package manager if not
already installed.

Once you have readline, using crash is as easy as just cloning the repo and
calling "make" in the root repo directory. As far as we know, it should work
on any unix system, but your milage may vary. It has been tested to work on
MacOSX 11 and Linux. After the sources are compiled, you should be able to
start the shell with ./crash

If you're wondering what this shell can do, you can take a look at the
test/scripts/ directory for some examples. In theory all posix compliant shell
scripts should work with crash.

Our shell also supports a rc file called .crashrc, which you have to place in
your user's home directory

what the project required us to do
============
x Display a promt when waiting for a new command
x Have a working history
x Search and launch the right executable (based on PATH etc.)
x Cannot use more than one global variable
x Handle single qoutes ''
x Handle double quotes ""
x Implement basic redirections <,>,<<,>>
x Implement pipes
x Handle enviroment variables
x Handle $?
x Handle ctrl-c, ctrl-d and ctrl-\
x Implement the following builtins
  x echo with option -n
  x cd with only a relative or absolute path
  x pwd with no options
  x export with no options
  x unset with no options
  x env with no options or arguments
  x exit with no options
x && and || with parenthesis for priorities
x Wildcards * should work for the current directory

Using only these externel functions:
readline, rl_clear_history, rl_on_new_line, rl_replace_line, rl_redisplay,
add_history, printf, malloc, free, write, access, open, read, close, fork,
wait, waitpid, wait3, wait4, signal, sigaction, sigemtpyset, sigaddset, kill,
exit, getcwd, chdir, stat, lstat, fstat, unlink, execve, dup, dup2, pipe,
opendir, readdir, closedir, strerror, perror, isatty, ttyname, ttyslot, ioctl,
getenv, tcsetattr, tcgetattr, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs

what we actually did
============
x everything in the mandatory and bonus part
x while/until loops
x if statements
x functions
x subshell
x case clause
x command substitution
x background commands
x all io redirect
x bang symbol
x proper expansion
x arithmetic expansion
x script files support
x rc file
x shift
x set/unset
x getopts
and much much more...

all according to the X/Open XSI Shell Command Language (Issue 4, Version 2)

what we learned
============
Shells are poorly standardized, multiple times when we were implementing
something, we read something along the lines of "some shells do it like this,
and other shell do it like that. So for maximum portability do both"... Which
we then did.

Also there are times when the standard (at least the one we used) is just plain
unclear about what something should do, making us check with multiple other
shells what their behaviour is. And learning that even the big shells like bash
and zsh do not have the same behaviour is some cases.

Jokes aside, we definitely learned a great deal about annoying parsing.
Resulting in the parser calling the lexer, and that lexer again calling the
parser and on and on and on... And how to properly manage child processes and
managing signalls.

And perhaps most of all, we know pretty much understand all (standard) shell
language. Knowing what to expect with what syntax. And also knowing the small
things like how spaces (do not) expand.

faq
============
Q:why so many files with so little amount of functions
A:the subject requires you to work in a specific format, which limits you to
  max 25 lines per function, and max 5 functions per file