If you ever want to see the graphical difference between two files in Perforce, here is the command:
p4merge file1 file2|
File 1 and File 2 can be different versions of the same file. For instance, if you wanted to see the difference between version 1 and version 2 of the same file, then the command would be:
p4merge file1@1 file1@2|
Unlike other "p4" commands, the "p4merge" command has a different argument to access the command's help. For p4merge, run the "p4merge -h" command to access the help for this command.
by Phil for Humanity