/simple_shell

👨‍💻own version of the default shell in Linux systems (bash). Included syscalls, standard I/O, child processes, signals, and interrupts. (C language)

Primary LanguageCMIT LicenseMIT

Gates Of S-Hell - Simple Shell

printf

Description

The simple shell is an application that reads lines from either a file or theterminal, interprets them, and executes them. This shell includes the basic functionality of a traditional Unix-like command line user interface. Standard functions and system calls employed in simple_shell include: access, execve, exit, fork, free, getline, malloc, perror, signal, stat, wait, write.

Requirements

simple_shell is designed to run in the Ubuntu 14.04.5 LTS linux environment and to be compiled using the GNU compiler collection v. gcc 4.8.4 with flags-Wall, -Werror, -Wextra, and -pedantic.

Installation

  • Compile: gcc -Wall -Werror -Wextra -pedantic *.c -o hsh
  • Run the shell in interactive mode: ./hsh
  • Run the shell in non-interactive mode:
  • Example echo "pwd" | ./hsh

Usage

The simple shell is an application that reads lines from either a file or theterminal, interprets them, and executes them. In a similar manner to sh, however with more limited functionality.

Signals:

While running in interactive mode, ignores the keyboard input Ctrl+c. Alternatively, an input of end-of-file Ctrl+d will exit the program.

User hits Ctrl+d in the third line.

~> ./shellby
~> ^C
~> ^C

Env

  • Usage: env
  • Prints the current environment.

Example:

$ ./hsh
~> env
NVM_DIR=/home/vagrant/.nvm
...

$?

? is substitued with the return value of the last program executed.

Example:

$ echo "echo $?" | ./hsh
0

$$

The second $ is substitued with the current process ID.

Example:

$ echo "echo $$" | ./hsh
6494

Exit

  • Usage: exit [STATUS]
  • Exits the shell.
  • The STATUS argument is the integer used to exit the shell.

Example:

$ ./hsh
~> exit

Examples

$ ./hsh 
~> ls -l
total 76
-rw-rw-r-- 1 vagrant vagrant   217 Apr 19 18:27 AUTHORS
-rw-rw-r-- 1 vagrant vagrant  2147 Apr 19 18:27 aux_functions.c
-rw-rw-r-- 1 vagrant vagrant   737 Apr 19 18:27 built_ins.c
-rw-rw-r-- 1 vagrant vagrant   764 Apr 19 18:27 env.c
-rw-rw-r-- 1 vagrant vagrant  1766 Apr 19 18:27 _execve.c
-rw-rw-r-- 1 vagrant vagrant   935 Apr 19 18:27 free.c
-rwxrwxr-x 1 vagrant vagrant   331 Apr 19 18:27 generate_authors
-rwxrwxr-x 1 vagrant vagrant 21421 Apr 19 18:39 hsh
-rw-rw-r-- 1 vagrant vagrant  1069 Apr 19 18:27 LICENSE
-rwxrwxr-x 1 vagrant vagrant  1939 Apr 19 18:27 man_1_simple_shell
-rw-rw-r-- 1 vagrant vagrant   252 Apr 19 18:27 _putchar.c
-rw-rw-r-- 1 vagrant vagrant  1559 Apr 19 18:27 README.md
-rw-rw-r-- 1 vagrant vagrant  1125 Apr 19 18:39 shell_header.h
-rw-rw-r-- 1 vagrant vagrant  1196 Apr 19 18:27 shell_main.c
~> pwd
/home/vagrant/simple_shell
~> exit
$

Authors

Duvan Jaramillo & Juan Felipe Rodriguez.