The command pacdiff is a maintenance utility for .pacorig, .pacnew and .pacsave files created by pacman. It is used to review and merge configuration files in Arch Linux.

Use case 1: Review files that need maintenance in interactive mode

Code:

pacdiff

Motivation: This use case allows you to review the configuration files that need maintenance in an interactive mode. It helps you to see the changes made in the updated package files and merge them with your customized configuration files.

Explanation: Running the command pacdiff without any arguments opens the .pacnew and .pacsave files in an interactive mode. It presents a diff view of the changes made in the configuration files and provides options to merge or skip the changes.

Example Output:

-etc
--+ link to /etc 'rsync'
-+etc
-standard
...
Diff /etc/profile.pacnew	Profile			Press Enter to view diff

Use case 2: Use sudo and sudoedit to remove and merge files

Code:

pacdiff --sudo

Motivation: This use case allows you to run pacdiff with elevated privileges, using sudo and sudoedit commands. It is useful if you need root access to remove or merge configuration files.

Explanation: By using the --sudo argument with pacdiff, it prompts you to enter your password and runs pacdiff with elevated privileges. It allows you to remove or merge files that require root access.

Example Output:

[sudo] password for user: 
Please enter the number of a file to view, or 'q' to quit: 

Use case 3: Review files needing maintenance, creating .bakups of the original if you (O)verwrite

Code:

pacdiff --sudo --backup

Motivation: This use case allows you to review the configuration files that need maintenance, but instead of overwriting the original files, it creates backups. Backups can be useful to revert changes if something goes wrong during the merging process.

Explanation: The --backup argument, when used with pacdiff, creates a .bak backup of the original configuration files before merging them. It helps in preserving the original files for future reference or in case any issues occur during the merge.

Example Output:

Please enter the number of a file to view, or 'q' to quit: 

Use case 4: Use a specific editor to view and merge configuration files

Code:

DIFFPROG=editor pacdiff

Motivation: This use case allows you to use a specific editor of your choice to view and merge configuration files. By default, pacdiff uses vim -d as the diff tool, but you can customize it to use your preferred editor.

Explanation: Setting the environment variable DIFFPROG to your preferred editor before running pacdiff allows you to use that editor for viewing and merging the configuration files. In the example code above, the editor is set to “editor”, but you can replace it with the actual command of your preferred editor.

Example Output:

Please enter the number of a file to view, or 'q' to quit: 

Use case 5: Scan for configuration files with locate instead of using pacman database

Code:

pacdiff --locate

Motivation: This use case allows you to scan for configuration files using the locate command instead of relying on the pacman database. It can be useful if the pacman database is not up-to-date or if you want to locate configuration files that are not managed by pacman.

Explanation: By using the --locate argument with pacdiff, it scans the system for configuration files using the locate command. It provides a broader scope for finding configuration files, as compared to the pacman database. This can be useful if you want to review or merge files that are not listed in the pacman database.

Example Output:

Please enter the number of a file to view, or 'q' to quit: 

Use case 6: Display help

Code:

pacdiff --help

Motivation: This use case displays the help information for using the pacdiff command. It provides a brief summary of the command and its available options.

Explanation: The --help argument, when used with pacdiff, displays the command usage and available options. It is useful to refer to the help documentation if you need guidance on using the pacdiff command.

Example Output:

Usage: pacdiff [OPTIONS] [FILE1..]

  Maintenance utility for `.pacorig`, `.pacnew` and `.pacsave` files created
  by pacman.

Options:
  --sudo          Use sudo and sudoedit for removal and merging.
  --backup        Back up the original file before merging.
  --interactive   Run in interactive mode.
  --all           Show all files without filtering.
  --locate        Use locate instead of pacman database.
  --verbosity {0..2}
                  Set verbosity level.
  --diff {diff,ediff}
                  Set diff program type, default is `vimdiff`.
  --quiet         Suppress all messages.
  --help          Show this message and exit.

Conclusion:

The pacdiff command is a versatile utility for reviewing and merging configuration files in Arch Linux. By understanding and utilizing its different use cases, you can effectively manage your configuration files and ensure that any updates or changes are properly merged with your custom configurations.