https://github.com/symonmuchemi/shell_emulator
Shell emulator
https://github.com/symonmuchemi/shell_emulator
c-programming shell
Last synced: 2 months ago
JSON representation
Shell emulator
- Host: GitHub
- URL: https://github.com/symonmuchemi/shell_emulator
- Owner: SymonMuchemi
- Created: 2023-07-18T18:01:33.000Z (almost 3 years ago)
- Default Branch: main
- Last Pushed: 2023-07-29T14:42:54.000Z (almost 3 years ago)
- Last Synced: 2025-02-16T08:42:52.781Z (over 1 year ago)
- Topics: c-programming, shell
- Language: C
- Homepage:
- Size: 78.1 KB
- Stars: 0
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Authors: AUTHORS
Awesome Lists containing this project
README
# 0x16. C - Simple Shell
## More Info
### Output
- Unless specified otherwise, your program *must have the exact same output* as sh (`/bin/sh`) as well as the exact same error output.
- The only difference is when you print an error, the name of the program must be equivalent to your `argv[0]` (See below)
Example of error with `sh`:
```shell
$ echo "qwerty" | /bin/sh
/bin/sh: 1: qwerty: not found
$ echo "qwerty" | /bin/../bin/sh
/bin/../bin/sh: 1: qwerty: not found
$
```
Some error with your program
```shell
$ echo "qwerty" | ./hsh
./hsh: 1: qwerty: not found
$ echo "qwerty" | ./././hsh
./././hsh: 1: qwerty: not found
$
```
## List of allowed functions
- `access` (man 2 access)
- `chdir` (man 2 chdir)
- `close` (man 2 close)
- `closedir` (man 3 closedir)
- `execve` (man 2 execve)
- `exit` (man 3 exit)
- `_exit` (man 2 _exit)
- `fflush` (man 3 fflush)
- `fork` (man 2 fork)
- `free` (man 3 free)
- `getcwd` (man 3 getcwd)
- `getline` (man 3 getline)
- `getpid` (man 2 getpid)
- `isatty` (man 3 isatty)
- `kill` (man 2 kill)
- `malloc` (man 3 malloc)
- `open` (man 2 open)
- `opendir` (man 3 opendir)
- `perror `(man 3 perror)
- `read` (man 2 read)
- `readdir` (man 3 readdir)
- `signal` (man 2 signal)
- `stat` (__xstat) (man 2 stat)
- `lstat` (__lxstat) (man 2 lstat)
- `fstat` (__fxstat) (man 2 fstat)
- `strtok` (man 3 strtok)
- `wait` (man 2 wait)
- `waitpid` (man 2 waitpid)
- `wait3` (man 2 wait3)
- `wait4` (man 2 wait4)
- `write` (man 2 write)
****
### Compilation
Your shel will be compiled this way:
```shell
gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o hsh
```
### Testing
Your shell should work like this in interactive mode:
```shell
$ ./hsh
($) /bin/ls
hsh main.c shell.c
($)
($) exit
$```
But also in non-interactive mode:
```shell
$ echo "/bin/ls" | ./hsh
hsh main.c shell.c test_ls_2
$
$ cat test_ls_2
/bin/ls
/bin/ls
$
$ cat test_ls_2 | ./hsh
hsh main.c shell.c test_ls_2
hsh main.c shell.c test_ls_2
$
```
### Checks
The Checker will be released at the end of the project (1-2 days before the deadline). We strongly encourage the entire class to work together to create a suite of checks covering both regular tests and edge cases for each task. See task `8. Test suite`.
## Tasks
### 0. Betty would be proud
Write a beautiful code that passes the Betty checks
*Repo:*
- GitHub repository: `simple_shell`
### 1. Simple shell 0.1
Write a UNIX command line interpreter.
- Usage: `simple_shell`
Your Shell should:
- Display a prompt and wait for the user to type a command. A command line always ends with a new line.
- The prompt is displayed again each time a command has been executed.
- The command lines are simple, no semicolons, no pipes, no redirections or any other advanced features.
- The command lines are made only of one word. No arguments will be passed to programs.
- If an executable cannot be found, print an error message and display the prompt again.
- Handle errors.
- You have to handle the “end of file” condition (`Ctrl+D`)
You don’t have to:
- use the `PATH`
- implement built-ins
- handle special characters : `"`, `'`, `,` \`, `*`, `&`, `#`
- be able to move the cursor
- handle commands with arguments
`execve` will be the core part of your Shell, don’t forget to pass the environ to it…
```shell
julien@ubuntu:~/shell$ ./shell
#cisfun$ ls
./shell: No such file or directory
#cisfun$ /bin/ls
barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell.c stat.c wait
env-environ.c exec fork mypid ppid printenv promptc shell stat test_scripting.sh wait.c
#cisfun$ /bin/ls -l
./shell: No such file or directory
#cisfun$ ^[[D^[[D^[[D
./shell: No such file or directory
#cisfun$ ^[[C^[[C^[[C^[[C
./shell: No such file or directory
#cisfun$ exit
./shell: No such file or directory
#cisfun$ ^C
julien@ubuntu:~/shell$ echo "/bin/ls" | ./shell
barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell.c stat.c wait
env-environ.c exec fork mypid ppid printenv promptc shell stat test_scripting.sh wait.c
#cisfun$ julien@ubuntu:~/shell$
```
*Repo:*
- GitHub repository: `simple_shell`
### 2. Simple shell 0.2
Simple shell 0.1 +
- Handle command lines with arguments
*Repo:*
- GitHub repository: `simple_shell`
### 3. Simple shell 0.3
Simple shell 0.2 +
- Handle the `PATH`
- `fork` must not be called if the command doesn’t exist
```shell
julien@ubuntu:~/shell$ ./shell_0.3
:) /bin/ls
barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell_0.3 stat test_scripting.sh wait.c
env-environ.c exec fork mypid ppid printenv promptc shell shell.c stat.c wait
:) ls
barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell_0.3 stat test_scripting.sh wait.c
env-environ.c exec fork mypid ppid printenv promptc shell shell.c stat.c wait
:) ls -l /tmp
total 20
-rw------- 1 julien julien 0 Dec 5 12:09 config-err-aAMZrR
drwx------ 3 root root 4096 Dec 5 12:09 systemd-private-062a0eca7f2a44349733e78cb4abdff4-colord.service-V7DUzr
drwx------ 3 root root 4096 Dec 5 12:09 systemd-private-062a0eca7f2a44349733e78cb4abdff4-rtkit-daemon.service-ANGvoV
drwx------ 3 root root 4096 Dec 5 12:07 systemd-private-062a0eca7f2a44349733e78cb4abdff4-systemd-timesyncd.service-CdXUtH
-rw-rw-r-- 1 julien julien 0 Dec 5 12:09 unity_support_test.0
:) ^C
julien@ubuntu:~/shell$
```
*Repo:*
- GitHub repository: `simple_shell`
### 4. Simple shell 0.4
Simple shell 0.3 +
- Implement the `exit` built-in, that exits the shell
- Usage: `exit`
- You don’t have to handle any argument to the built-in `exit`
*Repo:*
- GitHub repository: `simple_shell`
### 5. Simple shell 1.0
Simple shell 0.4 +
- Implement the `env` *built-in*, that prints the current environment
```shell
julien@ubuntu:~/shell$ ./simple_shell
$ env
USER=julien
LANGUAGE=en_US
SESSION=ubuntu
COMPIZ_CONFIG_PROFILE=ubuntu
SHLVL=1
HOME=/home/julien
C_IS=Fun_:)
DESKTOP_SESSION=ubuntu
LOGNAME=julien
TERM=xterm-256color
PATH=/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
DISPLAY=:0
$ exit
julien@ubuntu:~/shell$
```
*Repo:*
- GitHub repository: `simple_shell`
### 6. Simple shell 0.1.1
Simple shell 0.1 +
- Write your own `getline` function
- Use a buffer to read many chars at once and call the least possible the `read` system call
- You will need to use `static` variables
- You are not allowed to use `getline`
You don’t have to:
- be able to move the cursor
*Repo:*
- GitHub repository: `simple_shell`
### 7. Simple shell 0.2.1
Simple shell 0.2 +
You are not allowed to use `strtok`
*Repo:*
- GitHub repository: `simple_shell`
### 8. Simple shell 0.4.1
Simple shell 0.4 +
- handle arguments for the built-in `exit`
- Usage: `exit status`, where status is an integer used to `exit` the shell
```shell
julien@ubuntu:~/shell$ ./shell_0.4.1
$ exit 98
julien@ubuntu:~/shell$ echo $?
98
julien@ubuntu:~/shell$
```
*Repo:*
- GitHub repository: `simple_shell`
### 9. setenv, unsetenv
Simple shell 1.0 +
Implement the `setenv` and `unsetenv` builtin commands
-`setenv`
- Initialize a new environment variable, or modify an existing one
- Command syntax: `setenv VARIABLE VALUE`
- Should print something on stderr on failure
- `unsetenv`
- Remove an environment variable
- Command syntax: unsetenv VARIABLE
- Should print something on stderr on failure
*Repo:*
- GitHub repository: `simple_shell`
### 10. cd
Simple shell 1.0 +
Implement the builtin command `cd`:
- Changes the current directory of the process.
- Command syntax: `cd [DIRECTORY]`
- If no argument is given to cd the command must be interpreted like `cd $HOME`
- You have to handle the command `cd -`
- You have to update the environment variable `PWD` when you change directory
`man chdir`, `man getcwd`
*Repo:*
- GitHub repository: `simple_shell`
### 11. ;
Simple shell 1.0 +
- Handle the commands separator `;`
```shell
alex@~$ ls /var ; ls /var
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$ ls /hbtn ; ls /var
ls: cannot access /hbtn: No such file or directory
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$ ls /var ; ls /hbtn
backups cache crash lib local lock log mail metrics opt run spool tmp
ls: cannot access /hbtn: No such file or directory
alex@~$ ls /var ; ls /hbtn ; ls /var ; ls /var
backups cache crash lib local lock log mail metrics opt run spool tmp
ls: cannot access /hbtn: No such file or directory
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$
```
*Repo:*
- GitHub repository: `simple_shell`
### 12. && and ||
Simple shell 1.0 +
- Handle the `&&` and `||` shell logical operators
```shell
alex@~$ ls /var && ls /var
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$ ls /hbtn && ls /var
ls: cannot access /hbtn: No such file or directory
alex@~$ ls /var && ls /var && ls /var && ls /hbtn
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
ls: cannot access /hbtn: No such file or directory
alex@~$ ls /var && ls /var && ls /var && ls /hbtn && ls /hbtn
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
backups cache crash lib local lock log mail metrics opt run spool tmp
ls: cannot access /hbtn: No such file or directory
alex@~$
alex@~$ ls /var || ls /var
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$ ls /hbtn || ls /var
ls: cannot access /hbtn: No such file or directory
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$ ls /hbtn || ls /hbtn || ls /hbtn || ls /var
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$ ls /hbtn || ls /hbtn || ls /hbtn || ls /var || ls /var
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
backups cache crash lib local lock log mail metrics opt run spool tmp
alex@~$
```
*Repo:*
- GitHub repository: `simple_shell`
### 13. alias
Simple shell 1.0 +
Implement the `alias` builtin command
Usage: `alias [name[='value'] ...]`
- `alias`: Prints a list of all aliases, one per line, in the form `name='value'`
- `alias name [name2 ...]`: Prints the aliases `name`, `name2`, etc 1 per line, in the form `name='value'`
-alias `name='value' [...]`: Defines an alias for each `name` whose `value` is given. If `name` is already an alias, replaces its value with `value`
*Repo:*
- GitHub repository: `simple_shell`
### 14. Variables
Simple shell 1.0 +
- Handle variables replacement
- Handle the `$?` variable
- Handle the `$$` variable
```shell
julien@ubuntu:~/shell$ ./hsh
$ ls /var
backups cache crash lib local lock log mail metrics opt run snap spool tmp
$ echo $?
0
$ echo $$
5104
$ echo $PATH
/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
$ exit
julien@ubuntu:~/shell$
```
*Repo:*
- GitHub repository: `simple_shell`
### 15. Comments
Simple shell 1.0 +
Handle comments (`#`)
```shell
julien@ubuntu:~/shell$ sh
$ echo $$ # ls -la
5114
$ exit
julien@ubuntu:~/shell$
```
*Repo:*
- GitHub repository: `simple_shell`
### 16. File as input
Simple shell 1.0 +
- Usage: `simple_shell [filename]`
- Your shell can take a file as a command line argument
- The file contains all the commands that your shell should run before exiting
- The file should contain one command per line
- In this mode, the shell should not print a prompt and should not read from `stdin`
*Repo:*
- GitHub repository: `simple_shell`
****
## # USAGE
You can try our shell by following these steps:
> **Step 1:** Clone our repository using this command, (you need to have git installed on your machine first)
````
git clone https://github.com/MatriMariem/simple_shell
````
> **Step 2:** Change directory to simple_shell:
````
cd simple_shell
````
> **Step 3:** Compile the C files in this way:
````
gcc -Wall -Werror -Wextra -pedantic *.c -o hsh
````
> **Step 4:** Run the shell
````
./hsh
````
**Exiting the shell**
When you want to exit the shell, you can use one of the following methods:
> **1: Type the command "exit"**
````
exit
````
> **2: Press on Ctrl + D**