co - check out RCS revisions
co [options] file ...
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 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 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).
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).
8:00 pm lt
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.
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.
The -z option does not affect dates stored in RCS files, which are always UTC.
Strings of the form $keyword$ and $keyword:...$ embedded in the text are replaced with strings of the form $key_word:value$ 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:
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.
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.
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: $.
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 ci(1).
The following characters in keyword values are represented by escape sequences to keep keyword strings well-formed.
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.
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.
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 successful.
Author: Walter F. Tichy.
Manual Page Revision: ; Release Date: . Copyright (C) 1982, 1988, 1989 Walter F. Tichy. Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.
Walter F. Tichy, RCS--A System for Version Control, Software--Practice & Experience 15, 7 (July 1985), 637-654.
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.
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