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 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). same as -r, except that it also locks the
retrieved revision for the caller. 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:
126.96.36.199 $ 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. 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 $Revision: 188.8.131.52$. This
option is useful to ignore differences due to keyword substitution
when comparing different revisions of a file.
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: 184.108.40.206 $ 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. Generate only keyword values for keyword
strings. For example, for the Revision keyword, generate
the string 220.127.116.11 instead of $Revision: 18.104.22.168 $. 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. 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. quiet
mode; diagnostics are not printed. interactive mode; the
user is prompted and questioned even if the standard 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 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. 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 to state. 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. 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. 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 working files. Names are paired as explained
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).
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.
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: 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 (if locked). 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 locked). 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. 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
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
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) for details.
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
Author: Walter F. Tichy.
Revision Number: 22.214.171.124; 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), 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.
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