Preserve File Owner and Group Ownership in Unrar

This article explains how to restore and preserve original user and group ownership when extracting RAR archives using the command-line utility unrar. By utilizing specific flags and appropriate system permissions, you can ensure that files extracted on Unix-like systems retain their original ownership metadata rather than defaulting to the user running the extraction command.

The -ow Switch

To preserve or restore user and group ownership when extracting files, use the -ow switch with unrar.

sudo unrar x -ow archive.rar

• x: Extracts files with full paths.
• -ow: Tells unrar to restore file owner and group identities.

Prerequisites for Preserving Ownership

For ownership restoration to work successfully, two conditions must be met:

1. Elevated Privileges

On Linux and Unix-like operating systems, only the superuser (root) has permission to assign file ownership to another user. If you run unrar x -ow as a standard user, the operation will fail to change the owner and will fall back to assigning ownership to the current user. Always prepend the command with sudo or execute it as root.

2. Archive Creation with Ownership Data

The unrar utility can only restore ownership if that metadata was stored when the archive was initially created. Standard RAR creation commands do not store user and group IDs by default.

To ensure ownership data is present in an archive, the archive must be created using the -ow switch with the rar utility:

rar a -ow archive.rar /path/to/files

If an archive was created without the -ow flag, the ownership data does not exist inside the archive, and unrar will be unable to restore it.