co



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.

      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).

      If the selected revision has the Obsolete state, it will be not
      checked out until the option -O is specified.



OPTIONS

      -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(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).

      -l[rev]
           same as -r, except that it also locks the retrieved revision for
           the caller.

      -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
           revision locked by the caller, if there is one; otherwise, 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 FILE MODES below.

      -O   forces the checkout even if the selected version has the state
           Obsolete.

      -kkv Generate keyword strings using the default form, e.g. $Revision:
           1.5 $ 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.

      -kkvl
           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, generate the string $Revision$ instead of
           $Revision: 1.5 $.  This option is useful to ignore differences
           due to keyword substitution when comparing different revisions of
           a file.  Log messages are inserted after $Log$ keywords even if
           -kk is specified, since this tends to be more useful when merging
           changes.

      -ko  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: 1.5 $
           if that is how the string appeared when the file was checked in.
           This can be useful for file formats that cannot tolerate any
           changes to substrings that happen to take the form of keyword
           strings.

      -kb  Generate a binary image of the old keyword string.  This acts
           like -ko, except it performs all working file input and output in
           binary mode.  This makes little difference on Posix and Unix
           hosts, but on DOS-like hosts one should use rcs -i -kb to
           initialize an RCS file intended to be used for binary files.
           Also, on all hosts, rcsmerge(1) normally refuses to merge files
           when -kb is in effect.

      -kv  Generate only keyword values for keyword strings.  For example,
           for the Revision keyword, generate the string 1.5 instead of
           $Revision: 1.5 $.  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.

      -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.

      -I[rev]
           interactive mode; the user is prompted and questioned even if the
           standard input is not a terminal.

      -ddate
           retrieves the latest revision on the selected branch whose
           checkin date/time is less than or equal to date.  The date and
           time can 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           default is UTC
                1990-01-12 04:00:00+00           ISO 8601 (UTC)
                1990-01-11 20:00:00-08           ISO 8601 (local time)
                1990/01/12 04:00:00              traditional RCS 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  Internet RFC 822
                12-January-1990, 04:00 WET
           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.

      -M[rev]
           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).

      -sstate
           retrieves the latest revision on the selected branch whose state
           is set to state.

      -T   Preserve the modification time on the RCS file even if the RCS
           file changes because a lock is added or removed.  This option can
           suppress extensive recompilation caused by a make(1) dependency
           of some other copy of the working file on the RCS file.  Use this
           option with care; it can suppress recompilation even when it is
           needed, i.e. when the change of lock would mean a change to
           keyword strings in the other working file.

      -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.  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 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.

      -V   Print RCS's version number.

      -Vn  Emulate RCS version n, where n can be 3, 4, or 5.  This can 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 rcs -V; this works
           with newer versions of RCS.  If it doesn't work, 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 loses its
           default branch.  An RCS revision generated while emulating
           version 4 or earlier has a time stamp that is off by up to 13
           hours.  A revision extracted while emulating version 4 or earlier
           contains abbreviated dates of the form yy/mm/dd and can also
           contain different white space and line prefixes in the
           substitution for $Log$.

      -xsuffixes
           Use suffixes to characterize RCS files.  See ci(1) for details.

      -zzone
           specifies the date output format in keyword substitution, and
           specifies the default time zone for date in the -ddate option.
           The zone should be empty, a numeric UTC offset, or the special
           string LT for local time.  The default is an empty zone, which
           uses the traditional RCS format of UTC without any time zone
           indication and with slashes separating the parts of the date;
           otherwise, times are output in ISO 8601 format with time zone
           indication.  For example, if local time is January 11, 1990, 8pm
           Pacific Standard Time, eight hours west of UTC, then the time is
           output as follows:
                option    time output
                -z        1990/01/12 04:00:00        (default)
                -zLT      1990-01-11 20:00:00-08
                -z+05:30  1990-01-12 09:30:00+05:30
           The -z option does not affect dates stored in RCS files, which
           are always UTC.


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 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:

      $Author$
           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.

      $Header$
           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.

      $Locker$
           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 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:
                /*
                 * $Log$
                 */
           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:  $.

      $RCSfile$
           The name of the RCS file without a 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(1)
           or ci(1).

      The following characters in keyword values are represented by escape
      sequences to keep keyword strings well-formed.
           char     escape sequence
           tab      \t
           newline  \n
           space    \040
           $        \044
           \        \\


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 -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.


FILES

      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.


ENVIRONMENT

      RCSINIT
           options prepended to the argument list, separated by spaces.  See
           ci(1) for details.


DIAGNOSTICS

      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.


IDENTIFICATION

      Author: Walter F. Tichy.
      Modification: Ivica Crnkovic
      Manual Page Revision: 1.5; Release Date: 1996/10/08.
      Copyright c 1982, 1988, 1989 Walter F. Tichy.
      Copyright c 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.


SEE ALSO

      rcsintro(1), ci(1), ctime(3), date(1), ident(1), make(1), rcs(1),
      rcsclean(1), rcsdiff(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.


LIMITS

      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.