Minishell

Minishell is a dynamic shell implementation in C including redirection, piping, signal and expansion of environment variable as well as some essential builtins. It was developped as the first team project within 42 school cursus.

Usage

Interactive mode

./minishell

Command line mode

./minishell -c "commands"

To ignore leaks from readline with Valgrind (Thanks to @mcombeau)

valgrind --suppressions=.ignore_readline_leaks.supp --leak-check=full ./minishell

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Builtin function

Implemented builin functions include:

• echo with option -n
• cd with only a relative or absolute path
• pwd with no options
• env with no options or arguments
• export with no options
• unset with no options
• exit with no options

< Zoom on path parsing for cd >

No directory operand ('cd')

if $HOME is unset or doesn't exist --> error & return
else --> go to $HOME

Set curpath to the directory operand

Copy/duplicate the directory operand to curpath
If curpath does not begin with a character, set curpath to the string formed by the concatenation of
- the value of PWD - a character if the value of PWD did not end with a character
- and curpath.

Canonicalize the curpath value

a. Dot components and any characters that separate them from the next component shall be deleted.

b. For each dot-dot component, if there is a preceding component and it is neither root nor dot-dot, then: The preceding component, all characters separating the preceding component from dot-dot, dot-dot, and all characters separating dot-dot from the following component (if any) shall be deleted.

c. An implementation may further simplify curpath by removing any trailing characters that are not also leading characters, replacing multiple non-leading consecutive characters with a single , and replacing three or more leading characters with a single .
If, as a result of this canonicalization, the curpath variable is null, no further steps shall be taken.

chdir() called with curpath as the path argument.

If these actions fail for any reason, the cd utility shallbdisplay an appropriate error message and the remainder of this step shall not be executed.

The PWD environment variable shall be set to the value that curpath had on entry to the previous step (i.e., before conversion to a relative pathname). The OLDPWD environment variable shall also be set to the value of the old working directory (that is the current working directory immediately prior to the call to cd).

If there is insufficient permission on the new directory, or on any parent of that directory, to determine the current working directory, the value of the PWD environment variable is unspecified.

cf. man page