Greeter Script

The Greeter Script is a bash script that greets users based on their system status and group membership. It logs the greetings with timestamps and provides information about the user's special group status.

Usage

./greeter.sh [-l <log_file>] [-k <lock_file>] [-a] [username1] [username2] ...

Options:
  -a               Greet all users with an interactive shell.
  -l <log_file>    Specify a custom log file location (default: ${HOME}/greetings.log).
  -k <lock_file>   Specify a custom lock file location (default: /tmp/greeter.lock).
  -s               Show users with an interactive shell and exit.
  -h               Show this help message and exit.

Examples:
./greeter.sh -a
./greeter.sh -s
./greeter.sh -l /path/to/custom/logfile -k /path/to/custom/lockfile user1 user2

Installation

Clone the repository:

git clone <https://github.com/f-4-u/coursecontent-greeter.git>

Change into the script directory:

cd coursecontent-greeter

Make the script executable:

chmod u+x greeter.sh

Program Flow

1. Lock File Creation: Checks if the lock file exists. If not, it creates one to prevent multiple script instances from running simultaneously.
2. Log File Initialization: Checks if the log file exists. If not, it creates one and sets appropriate permissions.
3. User Existence and Groups: Checks if users provided as arguments exist on the system and belong to specified groups (adm, root, sudo, wheel).
4. Logging Greetings: Logs greetings with Unix timestamps into the specified log file.
5. Display Greetings: Displays greetings for each user based on their existence and group membership.
6. Unlock: Removes the lock file before exiting.

Exit Codes

0: Successful execution
1: Another instance of the script is running
2: Error creating or accessing lock or log file
3: No username provided
4: User does not exist on the system
5: Script execution failed
6: Script help menu was shown

Examples

./greeter.sh user1 user2
./greeter.sh -l /path/to/custom/logfile -k /path/to/custom/lockfile user1 user2
./greeter.sh -h

License

This script is licensed under the GPL-3.0 License.

Feel free to further modify it to meet your specific needs.