minishell

As beautiful as a shell

• Introduction
• Usage
• Builtins implemented
• Step by step
• Mindmap
• Study resources
• libft functions

introduction

The objective of this project is to create a simple shell and learn a lot about processes and file descriptors

The existence of shells is linked to the very existence of IT. At the time, all coders 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 to communicate with a computer using interactive lines of commands in a language somewhat close to english. With Minishell project, we’ll be able to travel through time and come back to problems people faced when Windows didn’t exist.

usage

Clone the repo git clone --recurse-submodules https://github.com/paulahemsi/minishell.git

Install Readline library make install

Compile Minishell make

Run ./minishell

Enjoy!

builtins_implemented

command	description
echo	echo the STRING(s) to standart output. -n flag: do not output the trailing newline
cd	change the shell working directory (with a relative or absolute path)
pwd	print name of current/working directory
export	set export attribute for shell variables
unset	unset values of shell variables
env	print the environment
exit	cause the shell to exit with the exit status specified

step_by_step

• Prompt implementation
• HashTable functions implementation
• Tokenizer implementation
• Variables expansion implementation
• Builtins implementation
• Parse and execute sistem design
• Signals implementation
• Parsing implementation
• Execute implementation
• Norme
• Bugs hunting

mindmap

study_resources

unix

• Unix Processes in C -video
• Termination Signals
• Shell Command Language
• Bash Guide for Beginners
• Programming Terminal Devices -video
• Introduction to System Programming -video
• Capturing exit status code of child process
• Notion with details about Readline lib, Termcaps and Signals
• Writing Your Own Shell

hashtable

• Hash Table in C/C++ – A Complete Implementation

tokenizer

• Lexical Analysis

more

• Notion with tons of materials

libft_functions

Click to expand

Part_1

ctype.h

Function	Description
ft_isalpha	checks for an alphabetic character.
ft_isdigit	checks for a digit (0 through 9).
ft_isalnum	checks for an alphanumeric character; it is equivalent to (isalpha(c)
ft_isascii	checks whether c is a 7-bit unsigned char value that fits into the ASCII character set.
ft_isprint	checks for any printable character including space.
ft_isupper	checks if character is uppercase.
ft_toupper	convert lowercase letters to uppercase
ft_tolower	convert uppercase letters to lowercase.

string.h

Function	Description
ft_memset	fills the first n bytes of the memory area pointed to by s with the constant byte c
ft_bzero	erases the data in the n bytes of the memory starting at the location pointed to by s, by writing zeros (bytes containing '\0') to that area.
ft_memcpy	copies n bytes from memory area src to memory area dest. The memory areas must not overlap. Use memmove(3) if the memory areas do overlap.
ft_memccpy	copies no more than n bytes from memory area src to memory area dest, stopping when the character c is found. If the memory areas overlap, the results are undefined.
ft_memmove	copies n bytes from memory area src to memory area dest. The two strings may overlap; the copy is always done in a non-destructive manner.
ft_memchr	scans the initial n bytes of the memory area pointed to by s for the first instance of c.
ft_memcmp	function compares the first n bytes (each interpreted as unsigned char) of the memory areas s1 and s2.
ft_strlen	The ft_strlen() function computes and returns the length of the string s.
ft_strlcpy	copies up to size - 1 characters from the NUL-terminated string src to dst, NUL-terminating the result.
ft_strlcat	appends the NUL-terminated string src to the end of dst. It will append at most size - strlen(dst) - 1 bytes, NUL-terminating the result.
ft_strchr	returns a pointer to the first occurrence of the character c in the string s.
ft_strrchr	returns a pointer to the last occurrence of the character c in the string s.
ft_strnstr	locates the first occurrence of the null-terminated string little in the string big, where not more than len characters are searched.
ft_strncmp	lexicographically compares the null-terminated strings s1 and s2. Returns an integer greater than, equal to, or less than 0, according as the string s1 is greater than, equal to, or less than the string s2. Compares not more than n characters. The comparison is done using unsigned characters, so that '\200' is greater than '\0'.
ft_strdup	returns a pointer to a new string which is a duplicate of the string s.

stdlib.h

Function	Description
ft_atoi	converts the initial portion of the string pointed to by str to int representation and returns the int.
ft_calloc	allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory. The memory is set to zero.

Part_2

string's functions

Function	Description
ft_substr	Allocates and returns a substring from the string ’s’. The substring begins at index ’start’ and is of maximum size ’len’.
ft_strjoin	Allocates and returns a new string, which is the result of the concatenation of ’s1’ and ’s2’.
ft_strtrim	Allocates and returns a copy of ’s1’ with the characters specified in ’set’ removed from the beginning and the end of the string.
ft_split	Allocates and returns an array of strings obtained by splitting ’s’ using the character ’c’ as a delimiter.
ft_strmapi	Applies the function ’f’ to each character of the string ’s’ to create a new string resulting from successive applications of ’f’.

string to int

Function	Description
ft_itoa	Allocates and returns a string representing the integer received as an argument. Negative numbers must be handled.

file-descriptor's functions

Function	Description
ft_putchar_fd	Outputs the character ’c’ to the given file descriptor.
ft_putstr_fd	Outputs the string ’s’ to the given file descriptor.
ft_putendl_fd	Outputs the string ’s’ to the given file descriptor, followed by a newline.
ft_putnbr_fd	Outputs the integer ’n’ to the given file descriptor.

Bonus

Linked Lists

Function	Description
ft_lstnew	Allocates and returns a new element. The variable ’content’ is initialized with the value of the parameter ’content’. The variable ’next’ is initialized to NULL.
ft_lstadd_front	Adds the element ’new’ at the beginning of the list.
ft_lstsize	Counts the number of elements in a list.
ft_lstlast	Returns the last element of the list.
ft_lstadd_back	Adds the element ’new’ at the end of the list.
ft_lstdelone	Takes as a parameter an element and frees the memory of the element’s content using the function ’del’ given as a parameter and free the element.
ft_lstclear	Deletes and frees the given element and every successor of that element, using the function ’del’ and free. Finally, the pointer to the list is set to NULL.
ft_lstiter	Iterates the list ’lst’ and applies the function ’f’ to the content of each element.
ft_lstmap	Iterates the list ’lst’ and applies the function ’f’ to the content of each element. Creates a new list resulting of the successive applications of the function ’f’. The ’del’ function is used to delete the content of an element if needed.

Double Linked Lists

Function	Description
ft_dlstnew	Allocates and returns a new element. The variable ’content’ is initialized with the value of the parameter ’content’. The variable ’next’ is initialized to NULL.
ft_dlstadd_front	Adds the element ’new’ at the beginning of the double linked list.
ft_dlstsize	Counts the number of elements in a double linked list.
ft_dlstlast	Returns the last element of the double linked list.
ft_dlstadd_back	Adds the element ’new’ at the end of the double linked list.
ft_dlstdelone	Takes as a parameter an element and frees the memory of the element’s content using the function ’del’ given as a parameter and free the element.
ft_dlstclear	Deletes and frees the given element and every successor of that element, using the function ’del’ and free. Finally, the pointer to the double linked list is set to NULL.
ft_dlstiter	Iterates the double linked list ’lst’ and applies the function ’f’ to the content of each element.
ft_dlstmap	Iterates the double linked list ’lst’ and applies the function ’f’ to the content of each element. Creates a new double linked list resulting of the successive applications of the function ’f’. The ’del’ function is used to delete the content of an element if needed.

Extras

Function	Description
ft_putchar	outputs the character c to the standard output.
ft_putstr	outputs a string to the standard output.
ft_putendl	outputs a string to the standard output, followed by a newline.
ft_putnbr	outputs the integer n to the standard output
ft_strequ	lexicographical comparison between s1 and s2. If the 2 strings are identical the function returns 1, or 0 otherwise.
ft_strnequ	lexicographical comparison between s1 and s2. If the 2 strings are identical the function returns 1, or 0 otherwise.
ft_strclr	sets every character of the string s to '\0'.
ft_isspace	tests for the white-space characters. For any locale, this includes the following standard characters: \v \n \t \r \f. Returns zero if the character tests false and returns non-zero if the character tests true.
ft_isblank	checks for a blank character; that is, a space or a tab.
ft_isxdigit	checks for hexadecimal digits.
ft_isnegative	checks if a number is negative.
ft_countdigit	Count the digits from an unsigned int.
ft_numlen	Count the digits from an int.
get_next_line	Read a line from stdin or fd
get_next_line_multifd	Read a line from multiples fd's
ft_add	variadic function which returns the sum of the numbers passed as arguments. The first argument must be the amount of numbers to be summed.
ft_itoa_hex	Convert the decimal unsigned integer received as argument to hexadecimal. Allocates and returns a string with the hex number.
ft_putnbr_unsigned	outputs the unsigned integer n to the standard output.
ft_free_and_null	frees and null the given pointer.

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