co(1)co(1)NAMEco - check out RCS revisions
[options] file ...
retrieves revisions from RCS files. Each file name ending in is taken
to be an RCS file. All other files are assumed to be working files.
retrieves a revision from each RCS file and stores it in the corre‐
sponding working file (see also rcsintro(5)).
Revisions of an RCS file can be checked out locked or unlocked. Lock‐
ing a revision prevents overlapping updates. A revision checked out
for reading or processing (e.g., compiling) need not be locked. A
revision checked out for editing and later checked in must normally be
locked. Locking a revision currently locked by another user fails (a
lock can be broken with the command, but poses inherent risks when
independent changes are being made simultaneously (see rcs(1)). with
locking requires the caller to be on the access list of the RCS file
unless: he is the owner of the file, a user with appropriate privi‐
leges, or the access list is empty. without locking is not subject to
access list restrictions.
A revision is selected by number, check-in date/time, author, or state.
If none of these options are specified, the latest revision on the
trunk is retrieved. When the options are applied in combination, the
latest revision that satisfies all of them is retrieved. The options
for date/time, author, and state retrieve a revision on the selected
branch. The selected branch is either derived from the revision number
(if given), or is the highest branch on the trunk. A revision number
can be attached to the options or
The caller of the command must have write permission in the working
directory, read permission for the RCS file, and either read permission
(for reading) or read/write permission (for locking) in the directory
that contains the RCS file.
The working file inherits the read and execute permissions from the RCS
file. In addition, the owner write permission is turned on, unless the
file is checked out unlocked and locking is set to (see rcs(1)).
If a file with the name of the working file exists already and has
write permission, aborts the check out if is given, or asks whether to
abort if is not given. If the existing working file is not writable,
it is deleted before the check out.
A number of temporary files are created. A semaphore file is created
in the directory of the RCS file to prevent simultaneous update.
A command applied to an RCS file with no revisions creates a zero-
length file. always performs keyword substitution (see below).
Locks the checked out revision for the caller.
If omitted, the checked out revision is not locked. See
option for handling of the revision number rev.
Prints the retrieved revision on the standard output rather than stor‐
in the working file. This option is useful when is part
of a pipe.
Quiet mode; diagnostics are not printed.
Retrieves the latest revision on the selected branch
whose check in date/time is less than or equal to date.
The date and time may be given in free format and are
converted to local time. Examples of formats for date:
Tue-PDT, 1981, 4pm Jul 21 (free format)
Fri April 16 15:52:25 EST 1982 (output of ctime(3C))
4/21/86 10:30am (format: mm/dd/yy hh:mm:ss)
Most fields in the date and time can be defaulted.
determines the defaults in the order year, month, day,
hour, minute, and second (from most- to least-signifi‐
cant). At least one of these fields must be provided.
For omitted fields that are of higher significance than
the highest provided field, the current values are
assumed. For all other omitted fields, the lowest pos‐
sible values are assumed. For example, the date
defaults to 10:30:00 of the 20th of the current month
and current year. Date/time fields can be delimited by
spaces or commas. If spaces are used, the string must
be surrounded by double quotes.
For 2-digit year input (yy) without the presence of the
century field, the following interpretation is taken:
Retrieves the latest revision whose number is less than or equal to
rev. If rev indicates a branch rather than a revision,
the latest revision on that branch is retrieved. rev is
composed of one or more numeric or symbolic fields sepa‐
rated by The numeric equivalent of a symbolic field is
specified with the and commands (see ci(1) and rcs(1)).
Retrieves the latest revision
on the selected branch whose state is set to state.
Retrieves the latest revision
on the selected branch that was checked in by the user
with login name login. If the argument login is omit‐
ted, the caller's login is assumed.
Generates a new revision that is the result
of the joining of the revisions on joinlist. joinlist
is a comma-separated list of pairs of the form where
rev2 and rev3 are (symbolic or numeric) revision num‐
bers. For the initial pair, rev1 denotes the revision
selected by the options For all other pairs, rev1
denotes the revision generated by the previous pair.
(Thus, the output of one join becomes the input to the
For each pair, joins revisions rev1 and rev3 with
respect to rev2. This means that all changes that
transform rev2 into rev1 are applied to a copy of rev3.
This is particularly useful if rev1 and rev3 are the
ends of two branches that have rev2 as a common ances‐
tor. If rev1 < rev2 < rev3 on the same branch, joining
generates a new revision that is similar to rev3, but
with all changes that lead from rev1 to rev2 undone. If
changes from rev2 to rev1 overlap with changes from rev2
to rev3, prints a warning and includes the overlapping
sections, delimited as follows:
For the initial pair, rev2 can be omitted. The default
is the common ancestor. If any of the arguments indi‐
cate branches, the latest revisions on those branches
are assumed. If the option is present, the initial rev1
Strings of the form and embedded in the text are replaced with strings
of the form where keyword and value are pairs listed below. Keywords
may be embedded in literal strings or comments to identify a revision.
Initially, the user enters strings of the form On check out, replaces
these strings with strings of the form If a revision containing strings
of the latter form is checked back in, the value fields are replaced
during the next checkout. Thus, the keyword values are automatically
updated on checkout.
Keywords and their corresponding values:
The login name of the user who checked in the revision.
The date and time the revision was checked in.
A standard header containing the
RCS file name, the revision number, the date, the
author, and the state.
The login name of the user who locked the revision (empty if not
The log message supplied during checkin,
preceded by a header containing the RCS file name, the
revision number, the author, and the date. Existing log
messages are replaced. Instead, the new log message is
inserted after This is useful for accumulating a com‐
plete change log in a source file.
The revision number assigned to the revision.
The full pathname of the
The state assigned to the revision with
Access Control Lists (ACLs)
Optional ACL entries should not be added to RCS files because they
might be deleted.
The RCS file name, the working file name, and the revision number
retrieved are written to the diagnostic output. The exit status always
refers to the last file checked out, and is 0 if the operation was suc‐
cessful, 1 if unsuccessful.
Assume the current directory contains a subdirectory named with an RCS
file named Each of the following commands retrieves the latest revision
from and stores it into
Check out version 1.1 of RCS file
Check out version 1.1 of RCS file to the standard output:
Check out the version of file that existed on September 18, 1992:
The command generates the working file name by removing the from the
end of the RCS file name. If the given RCS file name is too long for
the file system on which the RCS file should reside, terminates with an
There is no way to suppress the expansion of keywords, except by writ‐
ing them differently. In and this is done by embedding the null-char‐
acter into the keyword.
The option gets confused in some circumstances, and accepts no date
The option does not work for files containing lines consisting of a
RCS is designed to be used with text files only. Attempting to use RCS
with non-text (binary) files results in data corruption.
was developed by Walter F. Tichy.
SEE ALSOci(1), ident(1), rcs(1), rcsdiff(1), rcsmerge(1), rlog(1), rcsfile(4),