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 can 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
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 access list 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 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. 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
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: 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 substitution 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 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.
- -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 Coordinated 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
provided field, the time zone's current values are assumed. For all other
omitted fields, the lowest possible 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 recompilation 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 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 can 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.
- -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 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 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 substitution,
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 traditional RCS format of UTC without
any time zone indication 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 comments 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 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 the revision was checked in. With
-zzone a numeric time zone offset is appended; otherwise,
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
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 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 prefixes the
$Log$
line. For example, if the
$Log$ line is “
// $Log:
tan.cc $”, RCS prefixes each line of the log with
“
// ”. This is useful for languages with comments that
go to the end of the line. The convention for other languages is to use a
“
∗ ” prefix inside a multiline comment. For example,
the initial log comment of a C program conventionally is of the following
form:
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 successful.
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), 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.