What is a Perforce "shelved" file?

Question

In Perforce, what is a "shelved" file? What is the purpose of shelving a file that is open for edit in the workspace?

Answer 1

From the Perforce documentation:

Shelving is the process of temporarily storing work in progress on a Perforce Server without submitting a changelist. Shelving is useful when you need to perform multiple development tasks (such as interruptions from higher-priority work, testing across multiple platforms) on the same set of files, or share files for code review before committing your work to the depot.

The p4 shelve command creates, modifies, or discards shelved files in a pending changelist. Shelved files persist in the depot until they are discarded (by means of p4 shelve -d) or replaced by subsequent p4 shelve commands.

After shelving files, you can revert or modify them in your client workspace, and restore the shelved versions of those files to your workspace with the p4 unshelve command. While files are shelved, other users can unshelve the shelved files into their own workspaces, or into other client workspaces.

Files that have been shelved can also be accessed with the p4 diff, p4 diff2, p4 files, and p4 print commands, using the revision specifier @=change, where change is the pending changelist number.

If no arguments are specified, p4 shelve creates a new changelist, adds files from the user's default changelist, and (after the user completes a form similar to that used by p4 submit), shelves the specified files into the depot. If a file pattern is given, p4 shelve shelves only the files that match the pattern.