diff(1) and diff3(1) utilities, which are
necessary for RCS to operate. This document may be reproduced freely,
in whole or in part, provided that any usage of this document conforms
to the general copyright notice of the HOWTO series of the Linux
Documentation Project. See the file COPYRIGHT for details. Send all
complaints, suggestions, errata, and any miscellany to
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RCS, the revision control system, is a suite of programs that tracks changes in text files and controls shared access to files in work group situations. It is generally used to maintain source code modules. It lends itself to tracking revisions of document files as well.
RCS was written by Walter F. Tichy and Paul Eggert. The latest version which has been ported to Linux is RCS Version 5.7. There is also a semi-official, threaded version available. Much of the information in this HOWTO is taken from the RCS man pages.
RCS includes the rcs(1) program, which controls RCS archive
file attributes, ci(1) and co(1), which check files
in and out of RCS archives, ident(1), which searches RCS
archives by keyword identifiers, rcsclean(1), a program to
clean up files that are not being worked on or haven't changed,
rcsdiff(1), which runs diff(1) to compare the
revisions, rcsmerge(1), which merges two RCS branches into a
single working file, and rlog(1), which prints RCS log
messages.
Files archived by RCS may be text of any format, or binary if the
diff program used to generate change files handles 8-bit
data. Files may optionally include identification strings to aid in
tracking by ident(1). RCS uses the utilities
diff(1) and diff3(3) to generate the change files
between revisions. A RCS archive consists of the initial revision of
a file, which is version 1.1, and a series of change files, one for
each revision. Each time a file is checked out of an archive with
co(1), edited, and checked back into the archive with
ci(1), the version number is increased, for example, to 1.2,
1.3, 1.4, and so on for successive revisions.
The archives themselves commonly reside in a ./RCS
subdirectory, although RCS has other options for archive storage.
For an overview of RCS, see the rcsintro(1) manual page.
RCS needs diff(1) and diff3(3) to generate the
context diff files between revisions. The diff utilities suite needs
to be installed on your system, and when you install RCS, the software
will check for its presence.
Precompiled diffutils binaries are available at:
ftp://sunsite.unc.edu/pub/Linux/utils/text/diffutils-2.6.bin.ELF.tar.gzand its mirror sites. If you need to compile
diff(1), et
al., from source, it is located at:
ftp://prep.ai.mit.edu/pub/gnu/diffutils-2.7.tar.gzand its mirror sites.
You will also need to have the ELF libraries installed on your system if you want to install pre-built binaries. See the ELF-HOWTO for further details.
Get the source distribution of RCS Version 5.7. It is available at
ftp://sunsite.unc.edu/pub/Linux/devel/vc/rcs-5.7.src.tar.gzand its mirrors. After you have unpacked the archive into your source tree, you need to configure RCS for your system. This is done via the
configure script in the source directory, which you need to
execute first. This will generate a Makefile and the
appropriate conf.sh for your system. You can then type
make installwhich will build the binaries. At some point you may need to
su to root so the binaries can be installed in the
correct directories.
The program rcs(1) does the work or creating archives and
modifying their attributes. A summary of rcs(1) options may
be found in the rcs(1) manual page.
The easiest way to create an archive is first to mkdir RCS in
the current directory, then initialize the archive with the
rcs -i name_of_work_filecommand. This creates and archive with the name
./RCS/name_of_work_file,v and requests a text message
describing the archive, but it does not deposit any revisions in the
archive. You can turn on or off strict archive locking with the
commands
rcs -L name_of_work_fileand
rcs -U name_of_work_filerespectively. There are other options for controlling access to the archive, setting its format, and setting revision numbers, which are covered in the
rcs(1) manual page.
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.
The rlog(1) program provides information about the archive
file and the logs of each revision stored in it. A command like
rlog work_file_namewill print the version history of the file, each revision's creation date and
userids of author and the person who locked the
file. You can specify archive attributes and revision parameters to
view.
co(1) maintains a list of keywords of the RCS database which
are expanded when the working file is checked out. The keyword
$Id$ in a document will expand to a string which
contains the file name, revision number, the date checked out, the
author, the revision status, and the locker, if any. Including the
keyword $Log$ will expand to the document's
revision history log.
These and other keywords may be used as search criteria of the RCS
archive. See the ident(1) man page for further details.
emacs(1) Version Control.The Version Control facility of emacs(1) works as a front end
to RCS. This information applies specifically to Version 19.34 of GNU
Emacs, which is provided with the major Linux distributions. When
editing a file with emacs(1) which is registered with RCS,
the command vc-toggle-read-only (bound to C-x C-q by
default) will check a file in to the emacs's Version Control, and then
into RCS. Emacs will open a buffer where you can type a log message
to be included in the RCS log. When you are finished typing a log
entry, type C-c C-c to terminate your input and proceed with
the check-in process.
If you have selected strict locking for the file with RCS, you must
re-lock the file for editing by emacs(1). You can check the
file out for emacs's Version Control with the command % in
buffer-menu mode.
For more information, see the GNU Emacs Manual and the Emacs info pages.