https://github.com/codelixir/shella-ciao

Linux shell written in C language supporting some basic and user-defined commands
https://github.com/codelixir/shella-ciao

c cli hacktoberfest linux shell unix

Last synced: 19 days ago
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Linux shell written in C language supporting some basic and user-defined commands

• Host: GitHub
• URL: https://github.com/codelixir/shella-ciao
• Owner: codelixir
• Created: 2021-09-19T09:41:26.000Z (about 3 years ago)
• Default Branch: main
• Last Pushed: 2021-10-12T07:13:24.000Z (about 3 years ago)
• Last Synced: 2024-07-12T19:27:51.943Z (4 months ago)
• Topics: c, cli, hacktoberfest, linux, shell, unix
• Language: C
• Homepage:
• Size: 283 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Shella Ciao

[![forthebadge](https://forthebadge.com/images/badges/made-with-c.svg)](https://forthebadge.com)

## Running the Shell

```sh

$ cd code

$ make

...

$ ./a.out

```

## Commands and other features

`cd`, `echo`, `exit`, `ls`, `pinfo`, `pwd`, `repeat`, `jobs`, `sig`, `fg`, `bg` and system commands (`vi`, `subl`, etc)

- Piping ( `cmd1 | cmd 2 `  etc.)

- Redirection ( `cmd < input_file >> output_file`  etc.)

- Keyboard interrupts (`Ctrl+C`, `Ctrl+D`, etc.)

For knowing more about how the 'user-defined' commands work (commands which are different from standard bash/zsh commands), you can check [Part 1](Assignment%20Part%201.pdf) for `pinfo` or `repeat`, and [Part 2](Assignment%20Part%202.pdf) for `jobs`, `sig`, `fg` or `bg`.

## Code Files

| Files                 | Description |

| --------------------- | ----------- |

| bg.c, bg.h | Implementing the user defined `bg` command |

| cd.c, cd.h            | Implementing the `cd` command (navigate to a directory). The command takes up to one argument. |

| echo.c, echo.h        | Implementing the `echo` command (printing to the console). Tabs and multiple spaces are handled.        |

| execute.c, execute.h  | Contains the function for handling all commands and calling the respective functions. **This also takes care of any redirects like >, >>, <**        |

| fg.c, fg.g | Implementing the user defined `fg` function.|

| headers.h | Including all external header files          |

| handlers.c, handlers.h | Contains custom defined signal handler functions. Includes handlers for ^C, ^Z and background processes. |

| jobs.c, jobs.h | Implementation for user defined `jobs` command. Takes the flags `-s`, `-r`, `-sr`, `-rs`. If no flags are given, defaults to `rs` mode. |

| ls.c, ls.h | Implementing `ls` including multiple arguments (both files and directories) and flags `-l` and `-a`.         |

| main.c | The main function of the program. After initializing the shell, it reads input from the user, adds it to history, tokenizes it into commands, and sends it into the `execute` function (`execute.c`)            |

| pinfo.c, pinfo.h      | Implementing the user-defined `pinfo` command. It takes information about the process from `/proc` directory and prints selected information on the terminal.        |

| pipe.c, pipe.h | Implements piping. Contains a `master` function which is called recursively to take care of everything including multiple piping and any combination of piping and redirection. |

| prompt.c, prompt.h    | Controls the shell prompt, for example, `````` Here, `~` is the directory from which the shell is executed.        |

| pwd.c, pwd.h          | Implements `pwd` command (prints present working directory)        |

| redirection.c, redirection.h | Includes a function called `check_redirection` which is called from within `execute`. Before the commands are executed, this simplifies the command and reallocates stdin/stdout according to the specified symbols (`>/>>/<`). |

| repeat.c, repeat.h    | Implements `repeat` command (`repeat n [cmd]`)        |

| sig.c, sig.h | Implements the user defined `sig` command (`sig [jobnum] [signum]`) |

| syscom.c, syscom.h    | Implementing system commands using `execvp()`        |

| utils.c, utils.h      | Some utility functions that I use across files, for example `untildefy()` and `tildefy()` (converts path relative to `~` to absolute path, and vice versa), and other functions.        |

## Assumptions

| Feature/String | Limits |

| -------------- | ------------- |

| All paths      | 1024 chars |

| User input     | 256 chars, 32 commands |

| Command arguments        | 32 (excluding flags) |

(For in-built commands) There are some commands that work *slightly* differently on different versions of bash and zsh. In such cases, I have followed the behavior of bash-3.2.

---

*This was built as a part of the Operating Systems and Networks course, Monsoon 2021.*