SIMPLE SHELL

This project aims to create a simple UNIX command interpreter, it will emulate different aspects from the bash shell

SYNOPSIS

The simple shell provides a command line user interface, it can interact with input provided by the user, displaying functions and executin programs. For compilation we are using the folowwing libraries:

• stdio.h
• stdlib.h
• unistd.h
• string.h
• sys/types.h
• sys/stat.h
• signal.h

Auxiliary Functions

The functions listed below were written by the authors in order to comply with the project objectives:

• _strdup: Duplicates the array inserted in other location
• _strlen: Returns the lenght of a string
• _strcpy: Copies a string
• _strcmp: Compares two strings
• _strstr: Locates the first string into the second string
• _strchr: Locate the first ocurrence of a character
• str_concat: Concatenates two strings

Compilation

The simple shell is compiled in GCC with the following script

gcc -Wall -Werror -Wextra -pedantic *.c -o shell

• -Wall Consider all warnings including language specific warnings
• -Werror Make all warnings into errors.
• -Wextra Extra warnings suchs as Wstring-compare, -Woverride-init, etc.
• -pedantic Issue all the warnings demanded by strict ISO C

Execution

The simple shell can be called in both interative and non-interactive mode.

In the non-interactive mode, the shell will receive and run a script, for this reason it will not interact with the user

$ echo "/bin/ls" | ./shell
prompt.c process.c _atoi.c README.md man_1_simple_shell
$

In the interactive mode, the shell will be executed and a prompt will appear so the user can start typing commands and it will prompt again until the user type the exit command or Ctr-D.

$ ./shell
$ /bin/ls
prompt.c process.c _atoi.c README.md man_1_simple_shell

Commands with arguments

The simple shell handles commands with multiple arguments passed to programs

$ ls -l -a
total 108
-rw-rw-r--  1 vagrant vagrant  2016 Nov 27 01:30 #process.c#
drwxrwxr-x  3 vagrant vagrant  4096 Nov 27 16:52 .
drwxr-xr-x 15 vagrant vagrant  4096 Nov 26 14:39 ..
drwxrwxr-x  8 vagrant vagrant  4096 Nov 27 16:07 .git
-rw-rw-r--  1 vagrant vagrant  2091 Nov 27 16:52 README.md
-rw-rw-r--  1 vagrant vagrant   451 Nov 20 18:51 _atoi.c
-rw-rw-r--  1 vagrant vagrant   164 Nov 25 19:38 change_dir.c
-rw-rw-r--  1 vagrant vagrant   291 Nov 26 22:34 holberton.h
-rw-rw-r--  1 vagrant vagrant   846 Nov 27 15:52 man_1_simple_shell
-rw-rw-r--  1 vagrant vagrant  1681 Nov 26 22:33 process.c
-rwxrwxr-x  1 vagrant vagrant  9219 Nov 19 21:54 prompt
-rw-rw-r--  1 vagrant vagrant   965 Nov 26 22:34 prompt.c
-rwxrwxr-x  1 vagrant vagrant 13675 Nov 26 22:34 shell
-rw-rw-r--  1 vagrant vagrant    78 Nov 16 03:04 shell1.c
-rwxrwxr-x  1 vagrant vagrant  9849 Nov 19 13:48 str
-rwxrwxr-x  1 vagrant vagrant 17864 Nov 23 16:43 str_tok
$

Exit

In order to exit The simple shell, the user can type the command exit, this will terminate the program with an integer status. The shell handles End-of-file conditions, it will exit when the user types Ctrl-D. Note: The KeyStroke Ctrl-C will be ignored

Flowchart

Authors

Luis Medina, Fabio Gomez