ci(1) and co(1).ci(1) and co(1) are the commands used to check files in and out of their RCS archives. The ci(1) command may also be used to a check a file both in and out of an archive. In their simplest forms, ci(1) and co(1) take only the name of the working file.
ci name_of_work_fileand
co name_of_work_fileThe command form
ci -l name_of_work_filechecks in the file with locking enabled, and
co -l name_of_work_fileis performed automatically. That is,
ci -l checks the file out again with locking enabled.
ci -u name_of_work_filechecks the file into the archive, and checks it out again with locking disabled. In all cases, the user is prompted for a log message.
ci(1) will also create a RCS archive if one does not exist already.
If you don't specify a revision, ci(1) increments the version number of the last revision locked in the archive, and appends the revised working file to it. If you specify a revision on an existing branch, it must be higher than the existing revision numbers. ci(1) will also create a new branch if you specify the revision of a branch which does not exist. See the ci(1) and co(1) man pages for details.
ci(1) and co(1) have various options for interactive and non-interactive use. Again, see the ci(1) and co(1) man pages for details.