CO(1L) CO(1L)
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. Each file name
ending in `,v' is taken to be an RCS file; all other files
are assumed to be working files. If only a working file
is given, co tries to find the corresponding RCS file in
the directory ./RCS and then in the current directory.
For more details, see the file naming section below.
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. Co with
locking fails if the revision to be checked out is
currently locked by another user. (A lock may be broken
with the rcs(1L) command.) Co 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. Co 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(1L)). A revision or branch
number may be attached to any of the options -f, -l, -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).
-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(1L)) is
retrieved. Rev is composed of one or more
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numeric or symbolic fields separated by `.'.
The numeric equivalent of a symbolic field is
specified with the -n option of the commands
ci(1L) and rcs(1L).
-l[rev] same as -r, except that it also locks the
retrieved revision for the caller. See option
-r for handling of the revision number rev .
-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
latest revision locked by the caller; if no
such lock exists, 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 the
section on file modes below.
-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.
-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.
-sstate retrieves the latest revision on the selected
branch whose state is set to state.
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-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 above options -r, ..., -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. The
options -l and -u lock or unlock rev1.
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.
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
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revision.
$Date$ The date and time the revision was checked
in.
$Header$ A standard header containing the full
pathname of the RCS file, the revision
number, the date, the author, the state, and
the locker (if locked).
$Id$ Same as $Header$, except that the RCS file
name 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 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.
$RCSfile$ The name of the RCS file without 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(1L) or ci(1L).
FILE NAMING
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 co looks for an
RCS file of the form path2/RCS/workfile,v or
path2/workfile,v (in this order).
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If the RCS file is specified without a path in 1) and 2),
then co looks for the RCS file first in the directory
./RCS and then in the current directory.
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'.
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(1L)).
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 or -f is given, the
working file is deleted without asking.
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.
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.
IDENTIFICATION
Author: Walter F. Tichy, Purdue University, West
Lafayette, IN, 47907.
Revision Number: 1.4 ; Release Date: 89/05/02 .
Copyright (C) 1982, 1988, 1989 by Walter F. Tichy.
SEE ALSO
ci(1L), ident(1L), rcs(1L), rcsdiff(1L), rcsintro(1L),
rcsmerge(1L), rlog(1L), rcsfile(5L)
Walter F. Tichy, "Design, Implementation, and Evaluation
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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. Links to the RCS and working
files are not preserved. 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 `.'.
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