RLewis11769 / simple_shell

A simple shell application written in C

B.E.N.N.Y. Simple Shell

Description

B.E.N.N.Y. Shell is a simple UNIX command interpreter, or a shell program that is used to send commands to computers. The name is an acronym for Best Ever iNteractive and noN-interactive Yes, referring to its capability to be used in both interactive and non-interactive mode.

B.E.N.N.Y. Shell (hereafter referred to as BENNY) is a command-line interpreter that serves as the interface between a user and that user's operating system. BENNY is a program designed to read characters that are input into the terminal, interpret them, and pass those commands to the operating system to execute.

Who's a good shell?

Installation

1. Install

Clone BENNY into your system with the command:

git clone https://github.com/acbrimer/simple_shell.git

2. Compile

Compile BENNY with the command:

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

3. Use

BENNY is now ready to use in either interactive or non-interactive mode. See below for details.

Usage

Interactive Mode

In interactive mode, the user can have ongoing interaction with BENNY. BENNY will provide a prompt that will remain until the user exits from this mode.

To enter interactive mode, start the BENNY program with "./hsh" if compiled as directed.

$ ./hsh
BENNY$ [desired command]
BENNY$ [BENNY's output]
BENNY$ exit
$

Non-Interactive Mode

In non-interactive mode, the user can have a one-time interaction with BENNY.

To use BENNY in non-interactive mode, echo a command in double quotes and pipe it into BENNY with "./hsh" if compiled as directed.

$ echo "[desired command]" | ./hsh
$ [BENNY's output]
$

Examples

Interactive

Run a command with:

$ ./hsh
BENNY$ ls
a.out    builtin.c          free_mem_fns.c      log_command.c  man_1_simple_shell  string.c
AUTHORS  error.c            get_command_path.c  log.txt        parse_command.c     strtow.c
benny.h  execute_command.c  getenv.c            main.c         README.md
BENNY$

Include the path with:

$ ./hsh
BENNY$ /bin/cat hello
Hello!
BENNY$

Non-Interactive

Pipe a command into BENNY with:

$ echo "ls" | ./hsh
AUTHORS  builtin.c          free_mem_fns.c      getenv.c  main.c              parse_command.c  setenv.c  strtow.c
benny.h  execute_command.c  get_command_path.c  itoa.c    man_1_simple_shell  README.md        string.c
$

Use multi-line commands with:

$ echo "ls
> ls -a" | ./hsh
AUTHORS  builtin.c          free_mem_fns.c      getenv.c  main.c              parse_command.c  setenv.c  strtow.c
benny.h  execute_command.c  get_command_path.c  itoa.c    man_1_simple_shell  README.md        string.c
.      AUTHORS    error.c            get_command_path.c  .gitignore     main.c              README.md
..     benny.h    execute_command.c  getenv.c            log_command.c  man_1_simple_shell  string.c
a.out  builtin.c  free_mem_fns.c     .git                log.txt        parse_command.c     strtow.c
$

Features

• Zero memory leaks
• Custom env builtin command
• Custom exit builtin command
• Custom setenv builtin command
• Custom unsetenv builtin command
• Custom cd builtin command
• Custom _getenv function
• Custom _strtok function
• Ctrl-D exits the program
• Ctrl-C does not exit the program

Structure

Main Structure

main.c

• Prototypes:
  • void check_linelen(char *exename, char *cmdBuffer, int mode, int linelen);
  • void sigint_handler(int sig);
  • int main(int argc, char **argv);

parse_command.c

• Prototypes:
  • cmd_t *parse_command(char *cmd_str);
  • char *replace_char(char *str, char find, char replace);

execute_command.c

• Prototypes:
  • int execute_command(cmd_t *cmd, char *cmdBuffer, int linec, char *exename);
  • int check_file_exists(char *path);
  • void free_cmd_vars(cmd_t *cmd, char *cmd_path, char *cmdBuffer);

get_command_path.c

• Prototypes:
  • char **get_env_paths(void);
  • char *get_command_path(cmd_t *cmd);
  • char **add_pwd_to_paths(char *path, int pcount, char **env_paths);

free_mem_fns.c

• Prototypes:
  • char **free_str_array(char **arr);
  • void free_cmd_t(cmd_t *cmd);

Builtin Functions

builtin.c

• Prototypes:
  • int builtin(cmd_t *cmd, char *cmdBuffer);
  • void exitFunction(cmd_t *cmd, char *cmdBuffer);
  • void printEnv(void);

getenv.c

• Prototypes:
  • char *_getenv(const char *name);

setenv.c

• Prototypes:
  • int _unsetenv(const char *name);
  • int _setenv(const char *name, const char *value, int overwrite);
  • int _strncmp(char *s1, char *s2, unsigned int n);
  • int f_error(char *err, int eno, cmd_t *cmd, int linec, char *exe, char *path);

Helper Functions

strtow.c

• Prototypes:
  • char **_strtow(char *str, char delim);
  • char char *_strtok(char *str, int start, char delim);
  • int _charcount(char *str, char delim);
  • int _wordcount(char *str, char delim);

string.c

• Prototypes:
  • char *str_concat(char *s1, char *s2, char *delim);
  • int _strchr(char *s, char c);
  • int _strcmp(char *s1, char *s2);
  • char *_strdup(char *str);
  • int _strlen(char *s);

itoa.c

• Prototypes:
  • char *_itoa(int n);

Library Functions limited to:

• access
• execve
• exit
• fork
• free
• getcwd
• getline
• isatty
• malloc
• perror
• stat
• waitpid

Bugs

Yeah, probably.

Authors

BENNY was written by Adam Brimer and Rachel Lewis. See AUTHORS page for more details.

Links

A test suite for testing BENNY's capabilities can be found here.