CO(1) CO(1)
NAME
co - check out RCS revisions
SYNOPSIS
co [ options ] file ...
DESCRIPTION
co retrieves revisions from RCS files. Each file name
ending in `,v' is taken to be an RCS file. All other files
are assumed to be working files. co retrieves a revision
from each RCS file and stores it into the corresponding
working file.
Pairs of RCS files and working files may be specified in 3
ways (see also the example section).
1) Both the RCS file and the working file are given. The RCS
file name is of the form path1/workfile,v and the working
file name is of the form path2/workfile, where path1/ and
path2/ are (possibly different or empty) paths and workfile
is a file name.
2) Only the RCS file is given. Then the working file is
created in the current directory and its name is derived
from the name of the RCS file by removing path1/ and the
suffix `,v'.
3) Only the working file is given. Then the name of the RCS
file is derived from the name of the working file by
removing path2/ and appending the suffix `,v'.
If the RCS file is omitted or specified without a path, then
co looks for the RCS file first in the directory ./RCS and
then in the current directory.
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. Locking a
revision currently locked by another user fails. (A lock may
be broken with the rcs (1) command.) co with locking
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. co without locking is not
subject to accesslist restrictions.
A revision is selected by number, checkin date/time, author,
or state. If none of these options are specified, the latest
revision on the trunk is retrieved. When the options are
applied in combination, the latest revision that satisfies
all of them is retrieved. The options for date/time,
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author, and state retrieve a revision on the selected
branch. The selected branch is either derived from the
revision number (if given), or is the highest branch on the
trunk. A revision number may be attached to one of the
options -l, -p, -q, -M, or -r.
A co command applied to an RCS file with no revisions
creates a zero-length file. co always performs keyword
substitution (see below).
-l[rev] locks the checked out revision for the caller.
If omitted, the checked out revision is not
locked. See option -r for handling of the
revision number rev.
-p[rev] prints the retrieved revision on the std. 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.
-M[rev] the checked out file's last-modified date is set
to the revision date instead of the current date.
-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 and are converted to local time.
Examples of formats for date:
22-April-1982, 17:20-CDT,
2:25 AM, Dec. 29, 1983,
Tue-PDT, 1981, 4pm Jul 21 (free format),
Fri, April 16 15:52:25 EST 1982 (output of ctime).
Most fields in the date and time may be
defaulted. co determines the defaults 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 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 of the 20th of the
current month and current year. The date/time
must be quoted if it contains spaces.
-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. Rev is
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composed of one or more numeric or symbolic
fields separated by `.'. The numeric equivalent
of a symbolic field is specified with the -n
option of the commands ci and rcs.
-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.
-jjoinlist generates a new revision which is the join of the
revisions on joinlist. 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 options
-l, ..., -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 prints a warning and
includes the overlapping sections, delimited by
the lines <<<<<<< rev1, =======, and
>>>>>>> rev3.
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. If the option -l is present, the initial rev1 is
locked.
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.
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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.
Keywords and their corresponding values:
$Author$ The login name of the user who checked in the
revision.
$Class$ Prog, Def, Doc, or Test, depending on the class
assigned to the file with the -c option of the
rcs command.
$Date$ The date and time the revision was checked in.
$Header$ A standard header containing the RCS file name,
the revision number, the date, the author, and
the state.
$Locker$ 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 file
name, the revision number, the author, and the
date. 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.
$Revision$ The revision number assigned to the revision.
$Source$ The full pathname of the RCS file.
$State$ The state assigned to the revision with rcs -s
or ci -s.
DIAGNOSTICS
The RCS file name, the working file name, and the revision
number retrieved are written to the diagnostic output. The
exit status always refers to the last file checked out, and
is 0 if the operation was successful, 1 otherwise.
EXAMPLES
Suppose the current directory contains a subdirectory `RCS'
with an RCS file `io.c,v'. Then all of the following
commands retrieve the latest revision from `RCS/io.c,v' and
store it into `io.c'.
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co io.c; co RCS/io.c,v; co io.c,v;
co io.c RCS/io.c,v; co io.c io.c,v;
co RCS/io.c,v io.c; co io.c,v io.c;
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 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 if -q is
given, or asks whether to abort if -q is not given. If the
existing working file is not writable, it is deleted before
the checkout.
FILES
The caller of the command must have write permission in the
working directory, read permission for the RCS file, and
either read permission (for reading) or read/write
permission (for locking) in the directory which contains the
RCS file.
A number of temporary files are created. A semaphore file
is created in the directory of the RCS file to prevent
simultaneous update.
IDENTIFICATION
Author: Walter F. Tichy, Purdue University, West Lafayette,
IN, 47907.
Revision Number: 1.1 ; Release Date: 87/01/20 .
c
Copyright 1982 by Walter F. Tichy.
SEE ALSO
ci(1), ident(1), rcs(1), rcsdiff(1), rcsintro(1), rcsmerge(1), rlog(1), rcsfile(4)
Walter F. Tichy, ``Design, Implementation, and Evaluation of
a Revision Control System,'' in Proceedings of the 6th
International Conference on Software Engineering, IEEE,
Tokyo, Sept. 1982.
LIMITATIONS
The option -d gets confused in some circumstances, and
accepts no date before 1970. There is no way to 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 option -j does not work for files that contain lines
with a single `.'.
ORIGIN
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4.2 BSD
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