https://github.com/shubhamsharma0711/custom-unix-linux-shell

Custom Unix/Linux Shell, I developed as part of an Operating Systems course Assignment at IIITD. All Commands are implemented using both the fork system call and pthreads.
https://github.com/shubhamsharma0711/custom-unix-linux-shell

c cse231 cse231-iiitd custom-shell execvp fork iiitd linux-shell os os-assignment shell shell-assignment thread unix-shell

Last synced: about 1 month ago
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Custom Unix/Linux Shell, I developed as part of an Operating Systems course Assignment at IIITD. All Commands are implemented using both the fork system call and pthreads.

• Host: GitHub
• URL: https://github.com/shubhamsharma0711/custom-unix-linux-shell
• Owner: SHUBHAMSHARMA0711
• Created: 2023-05-16T13:26:36.000Z (about 3 years ago)
• Default Branch: main
• Last Pushed: 2024-01-23T15:15:13.000Z (over 2 years ago)
• Last Synced: 2025-09-11T11:55:33.170Z (9 months ago)
• Topics: c, cse231, cse231-iiitd, custom-shell, execvp, fork, iiitd, linux-shell, os, os-assignment, shell, shell-assignment, thread, unix-shell
• Language: C
• Homepage:
• Size: 20.5 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# Shell Description

This comprehensive overview provides details on external and internal commands implemented in the shell, along with error-handling mechanisms. Additionally, test cases and assumptions are outlined to guide users in utilizing the shell effectively.

## External Commands

### 1. ls

    - ls -a

    - ls -m

### 2. cat

    - cat -n

    - cat -E

### 3. date

    - date -u

    - date -I

### 4. rm

    - rm -v

    - rm -i

### 5. mkdir

    - mkdir -p

    - mkdir -v

## Internal Commands

### 1. cd

    - cd ~

    - cd ..

### 2. echo

    - echo *

    - echo --help

### 3. pwd

    - pwd -L

    - pwd -P

## Error Handling

1. **Command Not Found:** If the user enters any command other than the specified ones.

2. **No Such File or Directory:** In **cat** and **rm** commands for non-existing files, and in **cd** for non-existing directories.

3. **Invalid Option:** If the user enters an option not handled by the shell.

4. **Missing Operands:** In **cat** if the user enters it without any argument.

5. **Cannot Create Directory:** In **mkdir** if the user tries to create a duplicate directory.

6. **Fork Error (Child Process Not Created):** Error handling for creating a child process using the Fork System Call.

## Implementation Details

The shell can be implemented using both forks and threads. If someone wishes to use threads, they can add `&t` at the end of the command. For example:

- `ls -a &t`

- `cat -n cat.c &t`

- `date -I &t`

  

## Test Cases

### 1. ls

   - `ls -a` & `ls -a &t`

   - `ls -m` & `ls -m &t`

### 2. cat

   - `cat -n cat.c` & `cat -n cat.c &t`

   - `cat -E cat.c` & `cat -E cat.c &t`

### 3. date

   - `date -u` & `date -u &t`

   - `date -I` & `date -I &t`

### 4. rm hello.c

   - `rm -v hello.c` & `rm -v hello.c &t`

   - `rm -i hello.c` & `rm -i hello.c &t`

### 5. mkdir newDir

   - `mkdir -p newDir/newDir2` & `mkdir -p newDir/newDir2 &t`

   - `mkdir -v newDir` & `mkdir -v newDir &t`

## Assumptions

1. No unnecessary arguments will be passed in between or after the command.

2. **cat** and **rm** commands will not be passed a directory as an argument.

3. **mkdir** and **rm** commands will not be entered without any arguments.