frossiny / 42sh

42sh

How to build the project

git clone https://github.com/frossiny/42sh
cd 42sh
make

How to launch our Shell

After building it, just type:

./42sh

Launch our unit tests:

make tests

Features

Pipes:

Example: ls | cat -e
         ls | grep auteur | cat -e

Redirections:

They include:

• Simple redirections: > <
• Append to a file : >>
• Heredoc : <<
• File descriptor handling, including closing them : 2>&1 1>&-

Example: ls > file1 > file2
         cat -e < auteur > file 2>&-

Inhibitors

• Simple quotes: '
• Double quotes: "
• Backslashes (Escape character): \

Example: echo "Hello world"
         echo \
         salut

Logicals operator && and || and separator ;

&& executes the right-hand command of && only if the previous one succeeded.

|| executes the right-hand command of || only it the previous one failed.

; executes the right-hand command of ; always regardless whether the previous command succeeded or failed.

Example: make && ./42sh
         ls  ; cd /tmp
         cd /stuff || mkdir /stuff && cd /stuff         

History management

It include:

• ! token
  • !! Becomes the last command executed
  • !n Becomes the command number n in historydevient la commande numero n de l'historique
  • !-n Becomes the command number n in history, starting at the end
  • !str Becomes the last command executed starting with str
• history builtin
  • For more about history builtin, see here
• fc builtin
  • For more about fc builtin, see here
• history shortcut in line edition
  • For more about history shortcut, see here

Internal variables handling and expansions

Example: MYVAR=MyValue

Possibility to export them with the builtin export. Possibility to print them

Example: echo $USER

See set and unset for more details

Hash-table

• Load all binary found in $PATH
• Hash-table will be updated:
• If $PATH's value changes
• If the content of a directory referenced in $PATH is changed
• Hash binary - for more informations about hash binary, see here

Line Edition

• Multi-line line edition with syntax highlighting

• Subprompts with commands ending with \ " ' <<

Shortcut

arrow right : cursor moves right
arrow left : cursor moves left
arrow up : history previous
arrow down : history next
home : cursor goes to cmd first character
end : cursor goes to cmd last character
shift + arrow right : cursor moves to the next word
shift + arrow left : cursor moves to the previous word
backspace : delete the previous character
delete : delete the currently pointed character
shift + arrow up : cursor moves one line up
shift + arrow down : cursor moves one line down
ctrl + d : EOF / exit
ctrl + l : clear screen
ctrl + v : Go to visual mode (press again to deactivate)
ctrl + r : research into history
tabulation : launch autocompletion
IN VISUAL MODE
ctrl + y : copy selection
ctrl + x : cut selection
ctrl + p : replace the selection with the last copied selection

Job control

Possibility to put command in background

Example: ls -R / &

Can be managed with builtins: jobs, fg, bg

Arithmetic expansion

COMLETE HERE

Builtins [Posix compliant]

cd

Change directory

[-P], Handle the operand dot-dot physically; symbolic link components shall be resolved before dot-dot components are processed.
[-L], Handle the operand dot-dot logically; symbolic link components shall not be resolved before dot-dot components are processed

set

List all internal variables

Example: set

unset

Remove a variable from environnement

Example: unset PWD

alias

Allow to set aliases

Usage: alias key1=value1

Aliases can expand recursively.

unalias

Delete aliases with the alias builtin

Usage: unalias key1 key2 key3 ...

fc

Offer a more complete way to handle history

Usage: fc [-e ename] [-nlr] [first] [last] or fc -s [pat=rep] [cmd]

history

Usage: [-c] [-d offset] or history -awr

History is loaded at startup, and is located at $HOME/.42sh_history

jobs

List all jobs.

Usage: jobs [-l|-p] [job_id]

bg

Allows to relaunch a process stoped in background

Usage: fg [job_id]

fg

Relaunch a job put in background into foreground

Usage: fg [job_id]

hash

Handle hash table

Usage: hash [-r]

type

The type utility shall indicate how each argument would be interpreted if used as a command name.

Usage: type name

test

Test conditions and return true or false

Usage: test     test expression
                [ expression ]
                ! expression
                If expression is an integer, it becames the value returned.
        -h      -h:             Print this help with all the options listed.
        -b      -b file:        True if file exists and is a block special file.
        -c      -c file:        True if file exists and is a character special file.
        -d      -d file:        True if file exists and is a directory.
        -e      -e file:        True if file exists (regardless of type).
        -f      -f file:        True if file exists and is a regular file.
        -k      -k file:        True if file exists and its sticky bit is set.
        -p      -p file:        True if file is a named pipe (FIFO).
        -r      -r file:        True if file exists and is readable.
        -s      -s file:        True if file exists and has a size greater than zero.
        -u      -u file:        True if file exists and its set user ID flag is set.
        -w      -w file:        True if file exists and is writable.
                                True indicates only that the write flag is on.
                                The file is not writable on a read-only file system even if this test indicates true.
        -x      -x file:        True if file exists and is executable.
                                True indicates only that the execute flag is on.
                                The file is not executable on a read-only file system even if this test indicates true.
        -L      -L file:        True if file exists and is a symbolic link.
        -S      -S file:        True if file exists and is a socket.
        ---------------------------
        =       s1 = s2:        True if the strings s1 and s2 are identical.
        !=      s1 != s2:       True if the strings s1 and s2 are not identical.
        ---------------------------
        -eq     n1 -eq n2:      True if the intengers n1 and n2 are algebraically equal.
        -ne     n1 -ne n2:      True if the intengers n1 and n2 are not algebraically equal.
        -gt     n1 -gt n2:      True if the intengers n1 is algebraically greater than the integer n2.
        -ge     n1 -ge n2:      True if the intengers n1 is algebraically greater than or equal to the integer n2.
        -lt     n1 -lt n2:      True if the intengers n1 is algebraically less than the integer n2.
        -le     n1 -le n2:      True if the intengers n1 is algebraically less than or equal to the integer n2.

exit

Exit our shell

When a valid numeric argument is specified, exit with passed value

If multiple arguments are specified, an too many arguments error will be printed

If a non-numeric value is specified as argument, return code will be set to 255 and an invalid arguments error will be printed

Prompt expansions

PS1 can be exported to set custom prompt

COLOR CODES:
{black}, {white}, {red}, {green}, {brown}, {blue}, {cyan}, {purple}, {lgray}
POSSIBLE EXPANSIONS:
\u : the username of the current user
\v : the version of 42sh (e.g., 2.00)
\w : the current working directory, with $HOME abbreviated with a tilde
\j : the number of jobs currently managed by the shell
\h : the hostname up to the first ‘.’
\H : the hostname

References:

Posix Norm: https://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html

Bash manual: https://www.gnu.org/software/bash/manual/bash.html