/simple_shell

Primary LanguageC

Simple UNIX command interpreter

alt text

Description

The shell project is part of Holberton school curriculum and this custom shell suppose to replicate some of the functionalities of sh.

Compilation

The shell should be compiled on Ubuntu 14.04 LTS this way: gcc -Wall -Werror -Wextra -pedantic *.c -o hsh

Synopsis

This program must have the exact same output as sh as long as the exact same error output.

Clone repository: https://github.com/cnov20/simple_shell.git

Run the shell: ./hsh

Exit the shell: exitor ctrl + D

Exit status

Exits with code 0 on "end of file" condition. CTRL + D. Otherwise the shell will return the exit status of the last command executed, or if the exit builtin is used with a numeric argument, it will return the argument.

List of functions and system calls used

Custom functions Functionality
* _putchar output of chars & strings
* _strcmp compares two strings
* _putstring outputs strings
* _print_env print environment
* _getline delimited string input
* _strncat concatenates two strings
* _strlen calculate the length of a string

Header file

shell.h Contains all function prototypes and function structures used for the program:

  • char *_getenv_PATH(const char *name); printing the enviroment of variable PATH
  • int execve(const char *filename, char *const argv[], char *const envp[]); executes functions in child process
  • void _putstring(char *str); prints a string to standard output
  • unsigned int _strlen(char *str); finds the length of a string, excluding the null character
  • int _putchar(char c); writes a character to standard output
  • int _strcmp(char *s1, char *s2); compares two strings
  • char *_memcpy(char *dest, char *src, unsigned int n); function that copies memory area
  • char *_strdup(char *src); function that allocates space for and creates copy of given string
  • void shell_exit(int status); exit the shell when user types exit in prompt
  • char **tokenizer(char *line); tokenizes the environment by chosen delimeters
  • int execute_cmd(char **argv); function forks child process, if command is executable
  • char *_strncat(char *dest, char *src, int n); concatenates two strings
  • void _print_env(void); prints the environment

Examples

  • /bin/ls: prints the content of the current directory and prints new prompt right after the command was executed and the result was printed to standard output. alt text
  • /bin/pwd: prints the path of the current working directory to stdandard output and prints the prompt right after - ready for a new command to be entered. alt text
  • exit: builtin that terminate the shell alt text

Authors

Christopher Novelli: github account, twitter

Ekaterina Kalache: github account, twitter

License

Public, no copyright protection