Can you "ignore" a file in Perforce?
As of version 2012.1, Perforce supports the P4IGNORE environment variable. I updated my answer to this question about ignoring directories with an explanation of how it works. Then I noticed this answer, which is now superfluous I guess.
Assuming you have a client named "CLIENT", a directory named "foo" (located at your project root), and you wish to ignore all .dll files in that directory tree, you can add the following lines to your workspace view to accomplish this:
-//depot/foo/*.dll //CLIENT/foo/*.dll -//depot/foo/.../*.dll //CLIENT/foo/.../*.dll
The first line removes them from the directory "foo" and the second line removes them from all sub directories. Now, when you 'Reconcile Offline Work...', all the .dll files will be moved into "Excluded Files" folders at the bottom of the folder diff display. They will be out of your way, but can still view and manipulate them if you really need to.
You can also do it another way, which will reduce your "Excluded Files" folder to just one, but you won't be able to manipulate any of the files it contains because the path will be corrupt (but if you just want them out of your way, it doesn't matter).
-//depot/foo.../*.dll //CLIENT/foo.../*.dll
This works as of Perforce 2013.1, the new P4IGNORE mechanism was first added in release, 2012.1, described on the Perforce blog here:
https://www.perforce.com/blog/new-20121-p4ignore
As it's currently described, you set an environment variable "P4IGNORE" to a filename which contains a list of the files to ignore.
So you can check it out to see how you like it.
If you want a solution that will apply to all work-spaces without needing to be copied around, you (or your sysadmin) can refuse submission of those file-types through using lines like the below in the p4 protect table:
write user * * -//.../*.suo
write user * * -//.../*.obj
write user * * -//.../*.ccscc
I remember doing this before, but I don't have the necessary permissions to test this here. Check out Perforce's Sysadmin guide and try it out
Yes, But.
Perforce version 2012.1 added a feature known as p4ignore, inspired by Git. However the Perforce developers made a change to the behaviour, without justification, that happens to make the feature a lot less useful.
Whilst Git takes rules from all .gitignore files, Perforce doesn't know where to look until you specify a filename in an environment variable P4IGNORE. This freedom is a curse. You can't hack on two repositories that use different names for their ignore files.
Also, Perforce's ignore feature doesn't work out the box. You can set it up easily enough for yourself, but others don't benefit unless they explicitly opt-in. A contributor who hasn't may accidentally commit unwelcome files (eg. a bin folder created by a build script).
Git's ignore feature is great because it works out the box. If the .gitignore files are added to the repository (everyone does this), they'll work out the box for everyone. No-one will accidentally publish their private key.
Amusingly, the Perforce docs shows '.p4ignore' as an example ignore rule, which is backwards! If the rules are useful, they should be shared as part of the repository.
Perforce could still make good on the feature. Choose a convention for the file names, say p4ignore.txt, so the feature works out the box. Drop the P4IGNORE environment variable, it's counterproductive. Edit the docs, to encourage developers to share useful rules. Let users write personal rules in a file in their home folder, as Git does.
If you know anyone at Perforce, please email them this post.