In Linux, what does the 'r' permission signify for a file?

The 'r' permission in Linux specifically signifies "Read." When a user or process has read permission for a file, it means they can view the contents of that file. This is essential for users who need to access data contained within a file but do not have permission to modify or delete it.

This permission is critical for maintaining the security and integrity of data, as it allows users or processes to gather information without being able to alter the file itself. In the context of file permissions in Linux, 'r' is one of the three fundamental permissions, alongside 'w' (write) and 'x' (execute), which together define how a file can be interacted with by users and groups.