Sometimes a working copy's revision has extra data associated with it, for example it might be on a branch (Chapter 6, Branching and merging), or restricted to versions prior to a certain date by checkout -D or update -D. Because this data persists - that is, it applies to subsequent commands in the working copy - we refer to it as sticky.

Most of the time, stickiness is an obscure aspect of cvsnt that you don't need to think about. However, even if you don't want to use the feature, you may need to know something about sticky tags (for example, how to avoid them!).

You can use the status command to see if any sticky tags or dates are set:

$ cvs status driver.c
===================================================================
File: driver.c          Status: Up-to-date

    Version:            1.7.2.1 Sat Dec  5 19:35:03 1992
    rcs Version:        1.7.2.1 /u/cvsroot/yoyodyne/tc/driver.c,v
    Sticky Tag:         rel-1-0-patches (branch: 1.7.2)
    Sticky Date:        (none)
    Sticky Options:     (none)

The sticky tags will remain on your working files until you delete them with cvs update -A. The -A option retrieves the version of the file from the head of the trunk, and forgets any sticky tags, dates, or options.

The most common use of sticky tags is to identify which branch one is working on, as described in the section called “Accessing branches”. However, non-branch sticky tags have uses as well. For example, suppose that you want to avoid updating your working directory, to isolate yourself from possibly destabilizing changes other people are making. You can, of course, just refrain from running cvs update. But if you want to avoid updating only a portion of a larger tree, then sticky tags can help. If you check out a certain revision (such as 1.4) it will become sticky. Subsequent cvs update commands will not retrieve the latest revision until you reset the tag with cvs update -A. Likewise, use of the -D option to update or checkout sets a sticky date, which, similarly, causes that date to be used for future retrievals.

People often want to retrieve an old version of a file without setting a sticky tag. This can be done with the -p option to checkout or update, which sends the contents of the file to standard output. For example:

$ cvs update -p -r 1.1 file1 >file1
===================================================================
Checking out file1
rcs:  /tmp/cvs-sanity/cvsroot/first-dir/Attic/file1,v
VERS: 1.1
***************
$

However, this isn't the easiest way, if you are asking how to undo a previous checkin (in this example, put file1 back to the way it was as of revision 1.1). In that case you are better off using the -j option to update; for further discussion see the section called “Merging differences between any two revisions”.