jozsa / simple_shell

building a simple shell from scratch in c

0x15. C - Simple Shell

Description

In this project, we created a simple UNIX command line interpreter called "sash". Sash prints a command prompt and waits for the user to type a command and press enter. This intepreter can handle standard commands and user-created executables as well as some builtin functions.

Entry Functions

File	Function	Description
main_sash.c	main_sash	Tests interactivity of sash shell
enter_sash.c	enter_sash	Enter interactive mode of sash shell
enter_nonsash.c	enter_nonsash.c	Enter noninteractive mode of sash shell

Essential Functions

File	Function	Description
read_command.c	read_line	Reads the line entered into standard input and stores it in a buffer
split_line.c	split_line	Splits the line entered into standard input into a 2D array of strings
get_path.c	get_path	gets the PATH from the environment
tokenize.c	tokenize_path	Splits the PATH into individual directories
find_dir.c	find_dir	Finds the directory an executable is in and concatenates the command with the directory
execute.c	_execute	Executes non-builtin commands

Builtin Functions

File	Function	Description
builtins.c	run_builtin	Looks for the right builtin function and executes it
_env.c	_env	Prints the current environment
exit.c	exit_sash	Exits the Sash shell
chdir.c	_chdir	Changes the working directory

String Manipulation/Counting Functions

File	Function	Description
doubleptr_len	doubleptr_len	Counts the number of strings in a 2D array
str_cmp.c	str_cmp	Compares two strings and returns 0 if they are identical
str_len.c	str_len	Counts the length of a string and returns the length
str_str.c	str_str	Finds a substring in a string and returns that substring
str_cat.c	str_cat	Concatenates two strings together

Memory Allocation and Free Functions

File	Function	Description
double_ptr_list.c	double_ptr_list	Stores all allocated double pointers in a linked list
single_ptr_list.c	single_ptr_list	Stores all allocated pointers in a linked list
free_double_list.c	free_double_list	Frees all double pointers stored in linked list
free_single_list.c	free_single_list	Frees all single pointers stored in linked list

Non-Function Files

File	Description
sash.h	Header file containing all prototype functions and structs used in this project
man_1_simple_shell	man page for our program
AUTHORS	Lists individuals who contributed to this repository

Examples

$ ls -l file.c
-rw-rw-r-- vagrant vagrant 501 Nov 16 01:06 file.c

Entering ls -l file.txt will display the permissions and details of file.c

$ echo hi
hi

Entering echo hi will print hi to the standard output

echo "ls -l" | ./sash
-rw-rw-r-- vagrant vagrant 501 Nov 16 01:06 file.c

Piping echo "ls -l" into ./sash (non-interactive mode) will print the same output as entering "ls -l" in interactive mode

Authors

Stefan Silverio & Allison Weiner