jotavare / minishell

A simplified version of a unix shell, implemented as a command-line interpreter.

About • Important Information • Utilities • Command Examples • Norminette • License

ABOUT

The existence of shells is linked to the very existence of IT. At the time, all developers agreed that communicating with a computer using aligned 1/0 switches was seriously irritating. It was only logical that they came up with the idea of creating software to communicate with a computer using interactive lines of commands in a language somewhat close to the human language.

Thanks to Minishell, I travelled through time and came back to problems people faced when Windows didn’t exist. This project was about creating a simple shell, my own little bash. I learned a lot about processes and file descriptors.

• Subject PDF
• References GitHub

IMPORTANT INFORMATION

BEFORE EVALUATION

Check this list before delivering the project.

• Check the norminette for any errors.
• Check for segmentation faults, bus errors, double free, leaks, ...
• Must compile with -Wall, -Wextra and -Werror.
• Makefile must contain $(NAME), all, clean, fclean.
• Check for forbidden functions in your code.
• Check the subject for any other requirements.

NICE TO KNOW

Some nice-to-know commands that will help the evaluatee and the evaluator.

Important Commands	Description
make -n	Display the compilation information without actually compiling the code.
echo $?	Display the exit status of the last executed command.
nm -g ./minishell | grep " U "	Check for forbidden functions.
norminette	Checks the code for compliance with the coding style and guidelines.
-R CheckForbiddenSourceHeader	Check the code in header files.
cc -g -Wall -Wextra -Werror	Compile with the mandatory flags.
-fsanitize=address	Check for leaks.
-lreadline	Necessary to use the readline library.
ps -e or ps -A	See all processes currently running on your computer.
ps -a	Check for any dead children.

VALGRIND

Important valgrind flags that are necessary to know every single leak.

Valgrind Flags	Description
valgrind ./minishell	Check for leaks
-leak-check=full	Detailed checking for memory leaks.
--show-leak-kinds=all	Display all types of memory leaks.
--track-origins=yes	Tracks the origins of uninitialized values.
--verbose	Increases the level of verbosity.
--gen-suppressions=all	Ignore specific known issues or false positives.
--suppressions=readline.supp	Specifies the path to a suppression file.
--log-file=memleaks.log	Sets the name of the file.

To ignore leaks related to the readline and add_history functions, create a file called readline.supp with the following content:

{
    leak readline
    Memcheck:Leak
    ...
    fun:readline
}
{
    leak add_history
    Memcheck:Leak
    ...
    fun:add_history
}

valgrind --suppressions=readline.supp --leak-check=full --show-leak-kinds=all ./minishell

UTILITIES

Return Values ($?)

The values that a function returns when it completes.

• All Linux commands return an error code between 0 and 255.
• The value 0 represents the value true (command success).
• Values greater than 0 represent false (command failure).
• The error code of the last command used is contained in the variable $?.

$?	Description
1	Standard for general errors, such as a division by zero.
2	Improper use of built-in commands, per Bash documentation.
126	The command called cannot be executed, rights problem or the command is not executable.
127	Command not found, possible problem with $PATH or typing error.
128	Invalid command argument.
128+n	128 + signal number.
130	Finished with Ctrl + C (130 = 128 + 2).
255	Exit code out of bounds. Example: exit -1.

Command Reminders

More nice-to-know commands that may be useful in the future.

Command	Description
yes	Writes in an infinite loop yes teste.
ln	Bind a file or directory.
chmod	Change file permissions chmod 777 (all permissions) chmod 000 (no permissions).
cd	Change directory. cd - (last visited directory) cd (user directory) cd / (root).
clear	Clear the screen.
diff	Compare files line by line.
cmp	Write the first line of difference between 2 files.
pc	Copying files.
rm	Delete file.
rm -rf	Delete the directory recursively.
ls -l	Show the contents of the directory.
exit	Exit current process.
grep	Search for strings in files grep "printf" file.
mkdir	Create a directory.
rmdir	Delete a directory.
more	Displays a file page by page as in a man.
mv	Move or rename.
$PATH	Path to executables.
cat	Send the file to stdout.

CHMOD

Change the access permissions and the special mode flags of file system objects.

Rights	Number
r (read)	4
w (write)	2
x (execute)	1

Rights	Calculation	Total
---	0+0+0	0
r--	4+0+0	4
-w-	0+2+0	2
--x	0+0+1	1
rw-	4+2+0	6
-wx	0+2+1	3
x-ray	4+0+1	5
rwx	4+2+1	7

DATA TYPES

All data types, their size in bytes and the INT MIN and INT MAX range.

Data Types	Qualifiers	Size (in byte)	Range
char	char or signed char	1	-128 to 127
char	unsigned char	1	0 to 255
int	int or signed int	4	-2147483648 to 2147483647
int	unsigned int	4	0 to 4294967295
int	short int or short signed int	2	-32768 to 32767
int	unsigned short int	2	0 to 65535
int	long int or signed long int	4	-2147483648 to 2147483647
int	unsigned long int	4	0 to 4294967295
float	float	4	1.1754e-38 to 3.4028e+38
float	double	8	2.2250e-308 to 1.7976e+308
float	long double	10	3.4E-4932 to 3.4E+4932

COMMAND EXAMPLES

Some example commands that can be tested on minishell or break it.

Status	Definition
🟢	Working.
🟡	Didn't test yet.
🟣	Leaks or segmentation fault.
⚪	Weird behaviour.
🔴	Not working.
🔵	Not mandatory.

BLANK

Exploring fundamental commands in Minishell, unravelling the core of shell interactions.

Status	Command
🟢	<empty>
🟢	<spaces>
🟢	../../
🟢	$

SIGNALS

Understanding system signals, showcasing the shell's adaptability in various scenarios.

Status	Command
🟢	Ctrl + C
🟢	Ctrl + D
🟢	Ctrl + \
🟢	write something then press + Ctrl + C
🟢	write something then press + Ctrl + D
🟢	write something then press + Ctrl + \
🟢	cat + Ctrl + C
🟢	cat + Ctrl + D
🟢	cat + Ctrl + \
🟢	sleep 5 + Ctrl + C
🟢	sleep 5 + Ctrl + D
🟢	sleep 5 + Ctrl + \

PATH

Managing executable file access by manipulating the system path in Minishell.

Status	Command
🟢	/bin/echo
🟢	/bin/grep
🟢	/bin/ls
🟢	/bin/ls -la
🟢	/bin/cat
🟢	/bin/pwd
🟢	/bin/cd
🟢	/bin/export
🟢	/bin/env
🟢	/bin/exit

PWD

Locating the present directory through the pwd command in Minishell.

Status	Command
🟢	pwd
🟢	pwd a
🟢	pwd a b c d

EXPORT, ENV AND UNSET

Harnessing environment variables via export, env, and unset commands in Minishell.

Status	Command
🟢	ENV
🟢	eNv
🟢	env
🟢	env
🟢	env
🟢	env
🟢	UNSET
🟢	uNsEt
🟢	unset
🟢	unset
🟢	unset
🟢	unset
🟢	unset [variable]
🟢	unset [variable] [variable]
🟢	unset [all variables]
🟢	EXPORT
🟢	eXpOrT
🟢	export
🟢	export
🟢	export
🟢	export
🟢	export a=42
🟢	export a=24
🟢	export b=42
🟢	export a = 42
🟢	export a=" 42 "
🟢	export a=' 42 '
🟢	export a = 42
🟢	export a
🟢	export a=''
🟢	export a='"'
🟢	export a='\'
🟢	export a='$'
🟢	export a='\t'
🟢	export a='''
🟢	export =
🟢	export ==
🟢	export a=
🟢	export a=42=
🟢	export =a=42
🟢	export a==42
🟢	export "a=42"
🟢	export a="42"
🟢	export _=42
🟢	export 42=42
🟢	export a b = 42
🟢	export a= b= 42
🟢	export a=42 % b=42 @ c=42
🟢	export a=42 b=42 c=42
🟢	export A=a B=b C=c D=d E=e
🟢	export F=f G=g H=h I=i J=j
🟢	export K=k L=l M=m N=n O=o
🟢	export P=p Q=q R=r S=s T=t
🟢	export U=u V=v W=w X=x Y=y Z=z
🟢	export _=a; echo $_a

EXIT

Concluding Minishell's operations gracefully using the exit command.

Status	Command
🟢	EXIT
🟢	eXiT
🟢	exit
🟢	exit
🟢	exit
🟢	exit
🟢	exit test
🟢	exit "test"
🟢	"exit test"
🟢	"exit"
🟢	exit1
🟢	exita
🟢	exit exit
🟢	exit a
🟢	exit abc
🟢	exit a b c
🟢	exit a b c d
🟢	exit #
🟢	exit *
🟢	exit 0
🟢	exit 1
🟢	exit 123
🟢	exit 1234
🟢	exit 1 2 3 4
🟢	exit +
🟢	exit -
🟢	exit +10
🟢	exit -10
🟢	exit +2000
🟢	exit -2000
🟢	exit +-2000
🟢	exit -+2000
🟢	exit ++2000
🟢	exit --2000
🟢	exit -2147483649
🟢	exit 2147483648
🟢	exit 00000000000000000000
🟢	exit 11111111111111111111
🟢	exit'42'
🟢	exit '\t42'
🟢	exit '\t\f\r 42'
🟢	exit '42 '
🟢	exit '42\t'
🟢	exit '42\r'
🟢	exit '42\t\f\r '
🟢	exit '42 a'
🟢	exit '42\t\t\ta'

CD

Traversing directories seamlessly using the cd command in Minishell.

Status	Command
🟢	CD
🟢	cd
🟢	cd
🟢	cd
🟢	cd
🟢	cd .
🟢	cd ~
🟢	cd no_file
🟢	cd1
🟢	cd 0
🟢	cd 1
🟢	cd 123
🟢	cd 1234
🟢	cd 1 2 3 4
🟢	cd cd
🟢	cd a
🟢	cd abc
🟢	cd a b c
🟢	cd a b c d
🟢	cd ../../
🟢	cd ../../../../../../
🟢	cd ../../...
🟢	cd .../../..
🟢	cd .../../...
🟢	cd \
🟢	cd /
🟢	cd //
🟢	cd ///
🟢	cd -
🟢	cd $[VAR]

ECHO

Rendering text and variables in the terminal with the versatile echo command in Minishell.

Status	Command
🟢	ECHO
🟢	echO
🟢	ECHo
🟢	echo
🟢	echo echo
🟢	echo
🟢	echo
🟢	echo
🟢	echo .
🟢	echo ~
🟢	echo echo ~
🟢	"echo test"
🟢	echo "~"
🟢	echo '~'
🟢	echo ~123
🟢	echo 123~
🟢	echo ~/123
🟢	echo ~/123/456
🟢	echo #
🟢	echofile
🟢	echo file
🟢	echo no_file
🟢	echo file test
🟢	echo file test
🟢	echo file test file test
🟢	echo a"b"c
🟢	echo "a'b'c
🟢	echo "test"
🟢	echo test
🟢	echo 'test'
🟢	echo -n
🟢	echo -n -n -n -n
🟢	echo -nnnnnnnnnnnnnnnnnnnnnnnn
🟢	echo -n test -n
🟢	"echo" "-n"
🟢	echo -n test
🟢	echo -nn test
🟢	echo -n -n -n test
🟢	echo "-n" test
🟢	echo -n"-n" test
🟢	echo "-nnnn" test
🟢	echo "-n -n -n"-n test
🟢	echo "-n '-n'" test
🟢	echo -n file test
🟢	echo -n -n -n file test
🟢	echo $USER
🟢	echo "$USER"
🟢	echo "'$USER'"
🟢	echo " '$USER' "
🟢	echo text"$USER"
🟢	echo text"'$USER'" ' $USER '
🟢	echo "text" "$USER" "$USER"
🟢	echo ' $USER '
🟢	echo text "$USER" "$USER"text
🟢	echo ''''''''''$USER''''''''''
🟢	echo """"""""$USER""""""""
🟢	echo $USER'$USER'text oui oui oui oui $USER oui $USER ''
🟢	echo $USER '' $USER $USER '' $USER '' $USER -n $USER
🟢	echo ' \' ' \'
🟢	echo '\" ' " \"\""
🟢	echo \\\" \\\" \\\" \\\"\\\"\\\" \\\'\\\'\\\'
🟢	echo "$USER""$USER""$USER"
🟢	echo text"$USER"test
🟢	echo '$USER' "$USER" "text \' text"
🟢	echo '$USER'
🟢	echo $USER " "
🟢	echo "$USER""Users/$USER/file""'$USER'"'$USER'
🟢	echo "$USER$USER$USER"
🟢	echo '$USER'"$USER"'$USER'
🟢	echo '"$USER"''$USER'"""$USER"
🟢	echo " $USER "'$PWD'
🟢	echo " $USER \$ "'$PWD'
🟢	echo $USER=4
🟢	echo $USER=thallard
🟢	echo $USER
🟢	echo $?
🟢	echo $USER213
🟢	echo $USER$12USER$USER=4$USER12
🟢	echo $USER $123456789USER $USER123456789
🟢	echo $USER $9999USER $8888USER $7777USER
🟢	echo $USER $USER9999 $USER8888 $USER7777
🟢	echo $USER $USER9999 $USER8888 $USER7777 "$USER"
🟢	echo "$USER=12$USER"
🟢	echo "$9USER" "'$USER=12$SOMETHING'"
🟢	echo $PWD/file
🟢	echo "$PWD/file
🟢	echo "text" "text$USER" ... "$USER
🟢	echo $PW
🟢	echo "'"'ola'"'"
🟢	echo "'"' ola '"'"

NORMINETTE

At 42 School, it is expected that almost every project is written following the Norm, which is the coding standard of the school.

- No for, do...while, switch, case, goto, ternary operators, or variable-length arrays allowed;
- Each function must be a maximum of 25 lines, not counting the function's curly brackets;
- Each line must be at most 80 columns wide, with comments included;
- A function can take 4 named parameters maximum;
- No assigns and declarations in the same line (unless static);
- You can't declare more than 5 variables per function;
- ...

• 42 Norms - Information about 42 code norms. PDF
• Norminette - Tool to respect the code norm, made by 42. GitHub
• 42 Header - 42 header for Vim. GitHub

LICENSE

This work is published under the terms of Unlicense.