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exit builtin

Accept one argument or no arguments.

Exits with exit status 0 when executed without arguments.
Exits with the argument passed as exit status if the argument is valid.

Prints an error if the argument is non-numeric or if it exceds the LLONG_MIN or LLONG_MAX (-9223372036854775808 or 9223372036854775807 on 64-bit machine).
Also prints an error if there are more than one arguments.

Example output of exit test:

exit
bash: exit: test: numeric argument required

exits with exit status 2

Example output of exit 9223372036854775808 (64-bit)

exit
bash: exit: 9223372036854775808: numeric argument required

exits with exit status 2

Example output of exit a b c

exit
bash: exit: a: numeric argument required

exits with exit status 2 and prints an error only for the first argument

Example output of exit 1 a

exit
bash: exit: too many arguments

Does not exit in this case, instead it returns and set the last exit status of the command to 1

When there are multiple arguments:
If the first argument is not a valid format it exits with exit status 2 and prints the argument and numeric argument required
If the first argument is a valid argument it doen't exit but instead returns 1, sets the last exit status to 1 and prints too many arguments

If after semicolon ; token there is another semicolon ; token bash prints:

bash: syntax error near unexpected token `;;'

Currently, our shell prints only one semicolon:

minishell: syntax error near unexpected token `;'

After cat without any arguments, if you press ctrl-C, bash shows:
user42@salty-VirtualBox:~/github/minishell$ cat ^C user42@salty-VirtualBox:~/github/minishell$

And our minishell:
minishell> cat ^Cminishell>
A new line is missing

Fix echo when there are multiple -n flags or -nnnnnnn

Example:

cat some_file > first_file > second_file > third_file

bash will create first_file and second_file and will save the output of cat in the third_file

Currently, our minishell prints an error and set last command exit status to 2

Example:

< notafile ; echo $?

Bash output:

bash: notafile: No such file or directory
1

Minishell output:

minishell: notafile: No such file or directory
minishell: syntax error near unexpected token `;'
2

After some testing i think bash is setting the $_ variable before executing each command in pipeline then after the pipeline unsets it.

Example:

/usr/bin/env | sort | cat -ev
echo $_
ls | /usr/bin/env | sort
echo $_

In the pipeline the $_ variable is set but after the pipeline it's unset

Currently, our shell unsets the $_ variable before executing the pipeline and doesn't set it before executing a command, inside the pipeline.

To fix it we could set the $_ variable in fork() before executing a command in the pipeline.

Expected:
PWD environment variable should be initialized when starting the shell

Actual:
PWD environment variable is not initialized when starting the shell

Currently we're initializing the env variables to the value that are stored in environ

bash is setting PWD at start

How to test/ Example:

usr/bin/env -i TERM="xterm-256color" PATH="$PATH" bash --norc; echo $PWD

This command will start a new bash shell with only two environment variable TERM and PATH then print the value of PWD

usr/bin/env -i TERM="xterm-256color" PATH="$PATH" ./minishell; echo $PWD

This command will start a new minishell shell with only two environment variable TERM and PATH then print the value of PWD

Currently we do variable expansion ($?, $PWD, etc) when parsing the tokens and creating the commands.
So commands like in the example below have different output in our minishell than bash

unset TEST
export TEST=test; echo $TEST

One solution is to modify word_expansion() and move it from parse() function to the do_cmd() and do_pipeline()

There is an error when the PATH variable is an empty string "" or it has a ":" character at the start or the end of the string.

Bash will search in the current directory in this cases.

Currently our minishell returns an error.

Example:

echo -e '#!/bin/sh\necho bonjour' > somecmd
chmod +x somecmd
export PATH=''
somecmd ; echo $?

Bash output

bonjour
0

Minishell output:

minishell: somecmd: No such file or directory
127

After finishing the main loop, return the exit status of the last command.

Example:

non_existant_command
Ctrl-D

echo $? in parent shell

It should print 127

Example:

mkdir path
cp /usr/bin/which ./path/a
chmod 000 ./path/a
path/a

Bash output:

bash: path/a: Permission denied
126

Minishell output:

minishell: path/a: No such file or directory
127

Currently were removing the quotes of the environment variable twice, once when exporting the env then again when printing it.

Example:

export TEST=’\hello\\w\\\\orld’ ; echo $TEST 

Expected output:

’hello\w\\orld’

Actual output:

’hellow\orld’

Currently if the SHLVL is less than LONG_MIN or more than LONG_MAX our minishell is setting it to 0, bash is setting it to 1.

Example:

export SHLVL='18446744073709551615'
./minishell
echo $SHLVL

export SHLVL='-9223372036854775809'
./minishell
echo $SHLVL

Expected:

1

1

Current:

0

0

To fix it we could extract exit_atoll() function from msh_exit.c into a separate file and rename + use it for this feature too since it deals with long int overflows.

bash skips and ignores spaces at the start of exit argument

Examples:
bash

bash
exit '     10'
echo $?

Outputs
exit
10

Our minishell

./minishell
exit '     10'
echo $?

Outputs:
exit
minishell: exit: 10: numeric argument required
2

When a command is not found, bash show the following:
user42@salty-VirtualBox:/github/minishell$ notacommand
notacommand: command not found
user42@salty-VirtualBox:/github/minishell$

And our minishell shows:
minishell> anycommand
minishell: anycommand: Success
minishell>

Example:

unset PWD
cd

Expected:
To change directory to the home directory

Actual:
Print Error: Success and exits with exit status 1.

Example:

unset TEST
$TEST

After exporting an environment variable and printing $_ bash prints only the name of the env variable

Example:

export TEST=test ; echo $_

Outputs:

TEST

Currently, our shell outputs both the name and the value.

TEST=test

To fix it we could set $_ in export builtin, after evaluating the env name.

Backslash character should be removed inside double quotes if the next character is $

Example:

echo "\$"
echo "\$TEST"

Should print

$
$TEST

Currently is printing

\$
\$TEST

Currently our shell is executing commands that are not in path if a file with the same name is in the current working directory

Example:
From the directory with minishell binary (the root of the repository)

minishell

Expected

minishell: command not found

Actual:
minishell is executed and a new shell is created

bash skips and ignores spaces at the start of SHLVL

Examples:
bash

export SHLVL='     10'
bash
echo $SHLVL

Outputs 11

Our minishell

export SHLVL='     10'
./minishell
echo $SHLVL

Outputs 1

Currently, executing exit after a command that failed will exit from the program with exit status 0 instead of the exit status of the last command.

Example:

not_a_command
exit

Then in the parent shell

echo $?

Our minishell prints 0 and bash prints 127

When executing a file that doesn't have a correct executable format bash does nothing and sets exit status to 0.
execve returns ENOEXEC 8 Exec format error in this case so i think we can use this.

Example:

bash
echo > testfile ; chmod +x testfile ; ./testfile
echo $?

Output:
0

./minishell
echo > testfile ; chmod +x testfile ; ./testfile
echo $?

Output:
minishell: ./testfile: Exec format error
127

Currently if there is a redirection error in the middle of a pipeline we ignore that command and pipe the output of the previous to the input of the next. Bash will execute only the commands that are after the last command that had a redirection error.

Example:

echo ok | cat < notafile | cat -ev

Expected output:

bash: notafile: No such file or directory

Current output:

minishell: notafile: No such file or directory
ok$

We could fix this at the same time when we fix #92 because they are related.