ci [options] files
Check in revisions. ci stores the contents of the specified working files into their corresponding RCS files. Normally, ci deletes the working file after storing it. If no RCS file exists, then the working file is an initial revision. In this case, the RCS file is created and you are prompted to enter a description of the file. If an RCS file exists, ci increments the revision number and prompts you to enter a message that logs the changes made. Starting with RCS Version 5.6, if a working file is checked in without changes, the file reverts to the previous revision. In older RCS versions, you may end up having to check in a new revision that contains no changes.
The mutually exclusive options -u, -l, and -r are the most common. Use -u to keep a read-only copy of the working file (for example, so that the file can be compiled or searched). Use -l to update a revision and then immediately check it out again with a lock. This allows you to save intermediate changes but continue editing (for example, during a long editing session). Use -r to check in a file with a different release number. ci accepts the standard options -q, -V, -x, and -z.
Check the file in with a timestamp of date or, if no date is specified, with the time of last modification.
Force a checkin even if there are no differences.
Interactive mode; prompt user even when standard input is not a terminal (e.g., when ci is part of a command pipeline). ...