CO(1) GNU(1992/04/10) CO(1)
NAME
co - check out RCS revisions
SYNOPSIS
co [options] file ...
DESCRIPTION
co retrieves a revision from each RCS file and stores it into the
corresponding working file.
Pathnames matching an RCS suffix denote RCS files; all others denote
working files. Names are paired as explained in ci(1).
Revisions of an RCS file may be checked out locked or unlocked. Locking
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 checkin must normally be locked.
Checkout with locking fails if the revision to be checked out is
currently locked by another user. (A lock may be broken with rcs(1).)
Checkout with locking also requires the caller to be on the access list
of the RCS file, unless he is the owner of the file or the superuser, or
the access list is empty. Checkout without locking is not subject to
accesslist restrictions, and is not affected by the presence of locks.
A revision is selected by options for revision or branch number, checkin
date/time, author, or state. When the selection options are applied in
combination, co retrieves the latest revision that satisfies all of them.
If none of the selection options is specified, co retrieves the latest
revision on the default branch (normally the trunk, see the -b option of
rcs(1)). A revision or branch number may be attached to any of the
options -f, -I, -l, -M, -p, -q, -r, or -u. The options -d (date), -s
(state), and -w (author) retrieve from a single branch, the selected
branch, which is either specified by one of -f, ..., -u, or the default
branch.
A co command applied to an RCS file with no revisions creates a zero-
length working file. co always performs keyword substitution (see
below).
OPTIONS
-r[rev]
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. If rev is omitted, the
latest revision on the default branch (see the -b option of rcs(1))
is retrieved. If rev is $, co determines the revision number from
keyword values in the working file. Otherwise, a revision is
composed of one or more numeric or symbolic fields separated by
periods. The numeric equivalent of a symbolic field is specified
with the -n option of the commands ci(1) and rcs(1).
10/89 Page 1
CO(1) GNU(1992/04/10) CO(1)
-l[rev]
same as -r, except that it also locks the retrieved revision for
the caller.
-u[rev]
same as -r, except that it unlocks the retrieved revision if it was
locked by the caller. If rev is omitted, -u retrieves the revision
locked by the caller, if there is one; otherwise, it retrieves the
latest revision on the default branch.
-f[rev]
forces the overwriting of the working file; useful in connection
with -q. See also FILE MODES below.
-kkv Generate keyword strings using the default form, e.g. $Revision:
1.1 $ for the Revision keyword. A locker's name is inserted in the
value of the Header, Id, and Locker keyword strings only as a file
is being locked, i.e. by ci -l and co -l. This is the default.
-kkvl Like -kkv, except that a locker's name is always inserted if the
given revision is currently locked.
-kk Generate only keyword names in keyword strings; omit their values.
See KEYWORD SUBSTITUTION below. For example, for the Revision
keyword, generate the string $Revision$ instead of $Revision: 1.1
$. This option is useful to ignore differences due to keyword
substitution when comparing different revisions of a file.
-ko Generate the old keyword string, present in the working file just
before it was checked in. For example, for the Revision keyword,
generate the string $Revision: 1.1 $ instead of $Revision: 1.1 $ if
that is how the string appeared when the file was checked in. This
can be useful for binary file formats that cannot tolerate any
changes to substrings that happen to take the form of keyword
strings.
-kv Generate only keyword values for keyword strings. For example, for
the Revision keyword, generate the string 1.1 instead of $Revision:
1.1 $. This can help generate files in programming languages where
it is hard to strip keyword delimiters like $Revision: $ from a
string. However, further keyword substitution cannot be performed
once the keyword names are removed, so this option should be used
with care. Because of this danger of losing keywords, this option
cannot be combined with -l, and the owner write permission of the
working file is turned off; to edit the file later, check it out
again without -kv.
-p[rev]
prints the retrieved revision on the standard output rather than
storing it in the working file. This option is useful when co is
part of a pipe.
Page 2 10/89
CO(1) GNU(1992/04/10) CO(1)
-q[rev]
quiet mode; diagnostics are not printed.
-I[rev]
interactive mode; the user is prompted and questioned even if the
standard input is not a terminal.
-ddate
retrieves the latest revision on the selected branch whose checkin
date/time is less than or equal to date. The date and time may be
given in free format. The time zone LT stands for local time;
other common time zone names are understood. For example, the
following dates are equivalent if local time is January 11, 1990,
8pm Pacific Standard Time, eight hours west of Coordinated
Universal Time (UTC):
8:00 pm lt
4:00 AM, Jan. 12, 1990 note: default is UTC
1990/01/12 04:00:00 RCS date format
Thu Jan 11 20:00:00 1990 LT output of ctime(3) + LT
Thu Jan 11 20:00:00 PST 1990 output of date(1)
Fri Jan 12 04:00:00 GMT 1990
Thu, 11 Jan 1990 20:00:00 -0800
Fri-JST, 1990, 1pm Jan 12
12-January-1990, 04:00-WET
Most fields in the date and time may be defaulted. The default
time zone is UTC. The other defaults are determined in the order
year, month, day, hour, minute, and second (most to least
significant). At least one of these fields must be provided. For
omitted fields that are of higher significance than the highest
provided field, the time zone's current values are assumed. For
all other omitted fields, the lowest possible values are assumed.
For example, the date 20, 10:30 defaults to 10:30:00 UTC of the
20th of the UTC time zone's current month and year. The date/time
must be quoted if it contains spaces.
-M[rev]
Set the modification time on the new working file to be the date of
the retrieved revision. Use this option with care; it can confuse
make(1).
-sstate
retrieves the latest revision on the selected branch whose state is
set to state.
-w[login]
retrieves the latest revision on the selected branch which was
checked in by the user with login name login. If the argument
login is omitted, the caller's login is assumed.
10/89 Page 3
CO(1) GNU(1992/04/10) CO(1)
-jjoinlist
generates a new revision which is the join of the revisions on
joinlist. This option is largely obsoleted by rcsmerge(1) but is
retained for backwards compatibility.
The joinlist is a comma-separated list of pairs of the form
rev2:rev3, where rev2 and rev3 are (symbolic or numeric) revision
numbers. For the initial such pair, rev1 denotes the revision
selected by the above options -f, ..., -w. For all other pairs,
rev1 denotes the revision generated by the previous pair. (Thus,
the output of one join becomes the input to the next.)
For each pair, co 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
ancestor. If rev1<rev2<rev3 on the same branch, joining generates
a new revision which is like 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, co reports overlaps as described in
merge(1).
For the initial pair, rev2 may be omitted. The default is the
common ancestor. If any of the arguments indicate branches, the
latest revisions on those branches are assumed. The options -l and
-u lock or unlock rev1.
-Vn Emulate RCS version n, where n may be 3, 4, or 5. This may be
useful when interchanging RCS files with others who are running
older versions of RCS. To see which version of RCS your
correspondents are running, have them invoke rlog on an RCS file;
if none of the first few lines of output contain the string branch:
it is version 3; if the dates' years have just two digits, it is
version 4; otherwise, it is version 5. An RCS file generated while
emulating version 3 will lose its default branch. An RCS revision
generated while emulating version 4 or earlier will have a
timestamp that is off by up to 13 hours. A revision extracted
while emulating version 4 or earlier will contain dates of the form
yy/mm/dd instead of yyyy/mm/dd and may also contain different white
space in the substitution for $Log$.
-xsuffixes
Use suffixes to characterize RCS files. See ci(1) for details.
KEYWORD SUBSTITUTION
Strings of the form $keyword$ and $keyword:...$ embedded in the text are
replaced with strings of the form $keyword:value$ where keyword and value
are pairs listed below. Keywords may be embedded in literal strings or
comments to identify a revision.
Page 4 10/89
CO(1) GNU(1992/04/10) CO(1)
Initially, the user enters strings of the form $keyword$. On checkout,
co replaces these strings with strings of the form $keyword:value$. If a
revision containing strings of the latter form is checked back in, the
value fields will be replaced during the next checkout. Thus, the
keyword values are automatically updated on checkout. This automatic
substitution can be modified by the -k options.
Keywords and their corresponding values:
$Author$
The login name of the user who checked in the revision.
$Date$
The date and time (UTC) the revision was checked in.
$Header$
A standard header containing the full pathname of the RCS file, the
revision number, the date (UTC), the author, the state, and the
locker (if locked).
$Id$ Same as $Header$, except that the RCS filename is without a path.
$Locker$
The login name of the user who locked the revision (empty if not
locked).
$Log$ The log message supplied during checkin, preceded by a header
containing the RCS filename, the revision number, the author, and
the date (UTC). Existing log messages are not replaced. Instead,
the new log message is inserted after $Log:...$. This is useful
for accumulating a complete change log in a source file.
$RCSfile$
The name of the RCS file without a path.
$Revision$
The revision number assigned to the revision.
$Source$
The full pathname of the RCS file.
$State$
The state assigned to the revision with the -s option of rcs(1) or
ci(1).
FILE MODES
The working file inherits the read and execute permissions from the RCS
file. In addition, the owner write permission is turned on, unless -kv
is set or the file is checked out unlocked and locking is set to strict
(see rcs(1)).
10/89 Page 5
CO(1) GNU(1992/04/10) CO(1)
If a file with the name of the working file exists already and has write
permission, co aborts the checkout, asking beforehand if possible. If
the existing working file is not writable or -f is given, the working
file is deleted without asking.
FILES
co accesses files much as ci(1) does, except that it does not need to
read the working file.
ENVIRONMENT
RCSINIT
options prepended to the argument list, separated by spaces. See
ci(1) for details.
DIAGNOSTICS
The RCS pathname, the working pathname, and the revision number retrieved
are written to the diagnostic output. The exit status is zero if and
only if all operations were successful.
IDENTIFICATION
Author: Walter F. Tichy.
Revision Number: 1.1; Release Date: 1992/04/10.
Copyright © 1982, 1988, 1989 by Walter F. Tichy.
Copyright © 1990, 1991 by Paul Eggert.
SEE ALSO
ci(1), ctime(3), date(1), ident(1), make(1), rcs(1), rcsdiff(1),
rcsintro(1), rcsmerge(1), rlog(1), rcsfile(5)
Walter F. Tichy, RCS--A System for Version Control, Software--Practice &
Experience 15, 7 (July 1985), 637-654.
LIMITS
Links to the RCS and working files are not preserved.
There is no way to selectively suppress the expansion of keywords, except
by writing them differently. In nroff and troff, this is done by
embedding the null-character \& into the keyword.
BUGS
The -d option sometimes gets confused, and accepts no date before 1970.
Page 6 10/89