CVS keeps changing file permissions; why does it do that?

In general, CVS doesn't do a very good job of preserving permissions onfiles. When you import a project and then check it out, there is noguarantee that the file permissions in the new working copy will be thesame as when the project was imported. More likely, the working copyfiles will be created with the same standard permissions that younormally get on newly created files.

However, there is at least one exception. If you want to storeexecutable shell scripts in the project, you can keep them executable inall working copies by making the corresponding repository fileexecutable:

     floss$ ls -l /usr/local/newrepos/someproj
     total 6
     -r--r--r--   1 jrandom  users         630 Aug 17 01:10 README.txt,v
     -r-xr-xr-x   1 jrandom  users        1041 Aug 17 01:10 scrub.pl,v*
     -r--r--r--   1 jrandom  users         750 Aug 17 01:10 hello.c,v

Notice that although the file is executable, it is still read-only, asall repository files should be (remember that CVS works by making atemporary copy of the RCS file, doing everything in the copy, and thenreplacing the original with the copy when ready).

When you import or add an executable file, CVS preserves the executablebits, so if the permissions were correct from the start, you havenothing to worry about. However, if you accidentally add the filebefore making it executable, you must go into the repository andmanually set the RCS file to be executable.

The repository permissions always dominate. If the file isnonexecutable in the repository, but executable in the working copy, theworking copy file will also be nonexecutable after you do an update. Having your files' permissions silently change can be extremelyfrustrating. If this happens, first check the repository and see if youcan solve it by setting the appropriate permissions on the correspondingRCS files.

A feature called PreservePermissions has recently been added toCVS that may alleviate some of these problems. However, using thisfeature can cause other unexpected results (which is why I'm notrecommending it unconditionally here). Make sure you read the nodesconfig and Special Files in the Cederqvist before puttingPreservePermissions=yes in CVSROOT/config.