Preventing multiple checkouts

To ensure that only one user at a time can work on the file, use the +l (exclusive-open) file type modifier. For example:

$ p4 reopen -t binary+l file

Although exclusive locking prevents concurrent development, for some file types (binary files), merging and resolving are not meaningful, so you can prevent conflicts by preventing multiple users from working on the file simultaneously.

Your Helix Server administrator can use the p4 typemap command to ensure that all files of a specified type (for instance, //depot/.../*.gif for all .gif files) can only be opened by one user at a time. See the Helix Core Command-Line (P4) Reference.

The difference between p4 lock and +l is that p4 lock allows anyone to open a file for edit, but only the person who locked the file can submit it. By contrast, a file of type +l prevents more than one user from opening the file.