CO(1) USER COMMANDS 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 oth
ers denote working files. Names are paired as explained in
ci(1).
Revisions of an RCS file can be checked out locked or
unlocked. Locking a revision prevents overlapping updates.
A revision checked out for reading or processing (e.g., com
piling) 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 cur
rently locked by another user. (A lock can 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 can 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 cre
ates 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. Other
wise, a revision is composed of one or more numeric or
symbolic fields separated by periods. If rev begins
with a period, then the default branch (normally the
trunk) is prepended to it. If rev is a branch number
followed by a period, then the latest revision on that
branch is used. The numeric equivalent of a symbolic
field is specified with the -n option of the commands
ci(1) and rcs(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 revi
sion if it was locked by the caller. If rev is omit
ted, -u retrieves the revision locked by the caller, if
there is one; otherwise, it retrieves the latest revi
sion 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: 5.13 $ 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: 5.13 $. This option
is useful to ignore differences due to keyword substi
tution when comparing different revisions of a file.
Log messages are inserted after $Log$ keywords even if
-kk is specified, since this tends to be more useful
when merging changes.
-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: 5.13 $ if that is how the
string appeared when the file was checked in. This can
be useful for file formats that cannot tolerate any
changes to substrings that happen to take the form of
keyword strings.
-kb Generate a binary image of the old keyword string.
This acts like -ko, except it performs all working file
input and output in binary mode. This makes little
difference on Posix and Unix hosts, but on DOS-like
hosts one should use rcs -i -kb to initialize an RCS
file intended to be used for binary files. Also, on
all hosts, rcsmerge(1) normally refuses to merge files
when -kb is in effect.
-kv Generate only keyword values for keyword strings. For
example, for the Revision keyword, generate the string
5.13 instead of $Revision: 5.13 $. This can help gen
erate 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 com
bined 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.
-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 can 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 Coordi
nated Universal Time (UTC):
8:00 pm lt
4:00 AM, Jan. 12, 1990 default is UTC
1990-01-12 04:00:00+00 ISO 8601 (UTC)
1990-01-11 20:00:00-08 ISO 8601 (local time)
1990/01/12 04:00:00 traditional RCS 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 Internet RFC 822
12-January-1990, 04:00 WET
Most fields in the date and time can be defaulted. The
default time zone is normally UTC, but this can be
overridden by the -z option. 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 pro
vided field, the time zone's current values are
assumed. For all other omitted fields, the lowest pos
sible values are assumed. For example, without -z, 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.
-T Preserve the modification time on the RCS file even if
the RCS file changes because a lock is added or
removed. This option can suppress extensive recompila
tion caused by a make(1) dependency of some other copy
of the working file on the RCS file. Use this option
with care; it can suppress recompilation even when it
is needed, i.e. when the change of lock would mean a
change to keyword strings in the other working file.
-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.
-jjoinlist
generates a new revision which is the join of the revi
sions on joinlist. This option is largely obsoleted by
rcsmerge(1) but is retained for backwards compatibil
ity.
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 ances
tor. 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 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. The options -l and -u lock or unlock
rev1.
-V Print RCS's version number.
-Vn Emulate RCS version n, where n can be 3, 4, or 5. This
can 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 rcs -V; this works with newer versions of
RCS. If it doesn't work, have them invoke rlog on an
RCS file; if none of the first few lines of output con
tain 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 loses its default branch. An RCS revision
generated while emulating version 4 or earlier has a
time stamp that is off by up to 13 hours. A revision
extracted while emulating version 4 or earlier contains
abbreviated dates of the form yy/mm/dd and can also
contain different white space and line prefixes in the
substitution for $Log$.
-xsuffixes
Use suffixes to characterize RCS files. See ci(1) for
details.
-zzone
specifies the date output format in keyword substitu
tion, and specifies the default time zone for date in
the -ddate option. The zone should be empty, a numeric
UTC offset, or the special string LT for local time.
The default is an empty zone, which uses the tradi
tional RCS format of UTC without any time zone indica
tion and with slashes separating the parts of the date;
otherwise, times are output in ISO 8601 format with
time zone indication. For example, if local time is
January 11, 1990, 8pm Pacific Standard Time, eight
hours west of UTC, then the time is output as follows:
option time output
-z 1990/01/12 04:00:00 (default)
-zLT 1990-01-11 20:00:00-08
-z+05:30 1990-01-12 09:30:00+05:30
The -z option does not affect dates stored in RCS
files, which are always UTC.
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 can be embedded in literal strings or com
ments to identify a revision.
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 sub
stitution 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 the revision was checked in. With
-zzone a numeric time zone offset is appended; other
wise, the date is UTC.
$Header$
A standard header containing the full pathname of the
RCS file, the revision number, the date and time, the
author, the state, and the locker (if locked). With
-zzone a numeric time zone offset is appended to the
date; otherwise, the date is UTC.
$Id$ Same as $Header$, except that the RCS filename is with
out 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 num
ber, the author, and the date and time. With -zzone a
numeric time zone offset is appended; otherwise, the
date is 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.
Each inserted line is prefixed by the string that pre
fixes the $Log$ line. For example, if the $Log$ line
is " .}S 3 1 "" " "// $Log:" "tan.cc $"" "" ","" "" RCS
prefixes each line of the log with " .}S 3 1 "" "
"// "" "" "."" "" "" This is useful for languages with
comments that go to the end of the line. The conven
tion for other languages is to use a " .}S 3 1 "" " "*"
" " """" "" "" prefix inside a multiline comment. For
example, the initial log comment of a C program conven
tionally is of the following form:
/*
* $Log$
*/
For backwards compatibility with older versions of RCS,
if the log prefix is /* or (* surrounded by optional
white space, inserted log lines contain a space instead
of / or (; however, this usage is obsolescent and
should not be relied on.
$Name$
The symbolic name used to check out the revision, if
any. For example, co -rJoe generates $Name: Joe $.
Plain co generates just $Name: $.
$RCSfile$
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).
The following characters in keyword values are represented
by escape sequences to keep keyword strings well-formed.
char escape sequence
tab \t
newline \n
space \040
$ \044
\ \\
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)).
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 unless a revision number
of $ is specified.
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 suc
cessful.
IDENTIFICATION
Author: Walter F. Tichy.
Manual Page Revision: 5.13; Release Date: 1995/06/01.
Copyright © 1982, 1988, 1989 Walter F. Tichy.
Copyright © 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.
SEE ALSO
rcsintro(1), ci(1), ctime(3), date(1), ident(1), make(1),
rcs(1), rcsclean(1), rcsdiff(1), rcsmerge(1), rlog(1), rcs
file(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.
GNU Last change: 1995/06/01 1