barkas218 / simple_shell-1

A simple shell in C

0x16. C - Simple Shell

Description

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This team project is part of the first year curriculum of Holberton School. Simple Shell is a UNIX command line interpreter that replicates the sh program.

What we learned:

• How a shell works and finds commands
• Creating, forking and working with processes
• Executing a program from another program
• Handling dynamic memory allocation in a large program
• Pair programming and team work
• Building a test suite to check our own code
• How to manipulate the environment of the current process
• What is the difference between a function and a system call
• What are the three prototypes of main
• How does the shell use the PATH to find the programs
• How to execute another program with the execve system call
• How to suspend the execution of a process until one of its children terminates*

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Compile and run

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1. Git clone all this respository to your local directory.

$ git clone https://github.com/carlosz22/test_shell.git

2. Compile the program.

$ make all

• Makefile

3. Execute the shell.

$ ./shell

Note: You can also run this shell in non-interactive mode, by simply piping your desired commands into the shell executable.

Usage

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• Prints a prompt and waits for a command from the user
• Creates a child process in which the command is checked
• Checks for built-ins, aliases in the PATH, and local executable programs
• The child process is replaced by the command, which accepts arguments
• When the command is done, the program returns to the parent process and prints the prompt
• The program is ready to receive a new command
• To exit: press Ctrl-D or enter "exit" (with or without a status)
• Works also in non interactive mode

Examples

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# Interactive Mode
$ /bin/ls
foo main.c coquille.c README.md tests croissant.c

$ pwd
/home/vagrant/simple_shell

$ ls -l
total 60
drwxrwxr-x 7 vagrant vagrant  4096 Apr  7 01:48 foo
-rw-rw-r-- 1 vagrant vagrant   148 Apr  7 00:00 main.c
-rwxrw-r-- 1 vagrant vagrant    28 Apr  7 15:35 coquille.c

$ baguette
./shell: No such file or directory

# Non-interactive Mode
$ echo "ls -l" | ./shell

$ ls -l
total 60
drwxrwxr-x 7 vagrant vagrant  4096 Apr  7 01:48 foo
-rw-rw-r-- 1 vagrant vagrant   148 Apr  7 00:00 main.c
-rwxrw-r-- 1 vagrant vagrant    28 Apr  7 15:35 coquille.c

Builtin Commands

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This shell supports a variety of builtin commands:

cd - change directory

env - list the current environment variables

exit - exit the shell

help - display help for a builtin command

Note: To read the help information and syntax for a particular builtin command, run the following from the shell prompt:

$ help <builtin command>

Files

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File	Content
main.c	entry point, executing function
shell.h	function prototypes, standard libraries, structs
hsh_readline.c	read line functions
hsh_parseline.c	string to tokens parsing functions
hsh_execute.c	functions dealing with the shell builtins and command execution
hsh_getenv.c	functions dealing with environment variable
hsh_splitpath.c	functions that check the PATH for commands
hsh_string.c	function dealing with string conversion and operations
more_functions.c	conversion between string and number functions
man_1_simple_shell	Simple Shell man page (man ./man_1_simple_shell)

Authors

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• Cesar Velez - [email protected]
• Carlos Zuluaga - [email protected]