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co - check out RCS revisions
co [options] file...
retrieves the latest revision whose number is less than or equal to
rev. If rev indicates a branch rather than a revision, the latest revi-
sion on that branch is retrieved. If rev is omitted, the latest revi-
sion 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).
same as -r, except that it also locks the retrieved revision for the
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.
forces the overwriting of the working file; useful in connection with
-q. See also FILE MODES below.
Generate keyword strings using the default form, e.g. $Revision:
188.8.131.52 $ 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.
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, gen-
erate the string $Revision$ instead of $Revision: 184.108.40.206$. This option
is useful to ignore differences due to keyword substitution when com-
paring 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, gen-
erate the string $Revision: 1.1 $ instead of $Revision: 220.127.116.11 $ 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 18.104.22.168 instead of $Revision:
22.214.171.124 $. 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 key-
word 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.
prints the retrieved revision on the standard output rather than stor-
ing it in the working file. This option is useful when co is part of a
quiet mode; diagnostics are not printed.
interactive mode; the user is prompted and questioned even if the stan-
dard input is not a terminal.
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
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.
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).
retrieves the latest revision on the selected branch whose state is set
retrieves the latest revision on the selected branch which 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 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 revi-
sions on those branches are assumed. The options -l and -u lock or
-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 $Log$.
Use suffixes to characterize RCS files. See ci(1) for details.
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 work-
ing 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 lock-
ing 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 com-
bination, co retrieves the latest revision that satisfies all of them. If
none of the selection options is specified, co retrieves the latest revi-
sion 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).
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 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 revi-
sion 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:
The login name of the user who checked in the revision.
The date and time (UTC) the revision was checked in.
A standard header containing the full pathname of the RCS file, the
revision number, the date (UTC), the author, the state, and the locker
Same as $Header$, except that the RCS filename is without a path.
The login name of the user who locked the revision (empty if not
The log message supplied during checkin, preceded by a header contain-
ing 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.
The name of the RCS file without a path.
The revision number assigned to the revision.
The full pathname of the RCS file.
The state assigned to the revision with the -s option of rcs(1) or
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
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.
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.
The -d option sometimes gets confused, and accepts no date before 1970.
co accesses files much as ci(1) does, except that it does not need to read
the working file.
options prepended to the argument list, separated by spaces. See ci(1)
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.
Author: Walter F. Tichy.
Revision Number: 126.96.36.199; Release Date: 1993/10/07.
Copyright (C) 1982, 1988, 1989 by Walter F. Tichy.
Copyright (C) 1990, 1991 by Paul Eggert.
ci(1), ctime(3), date(1), ident(1), make(1), rcs(1), rcsdiff(1), rcsin-
tro(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.