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co(1)

NAME

       co - check out RCS revisions

SYNOPSIS

       co [options] file ...

DESCRIPTION

       co  retrieves a revision from each RCS file and stores it into the cor-
       responding 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.  Lock-
       ing 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 sin-
       gle  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).

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 revi-
	      sion on that branch is used.  The numeric equivalent of  a  sym-
	      bolic  field  is	specified  with  the -n option of the commands
	      ci(1) and rcs(1).
	      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.

       -kkv   Generate keyword strings using the default form, e.g. $Revision:
	      1.6 $ 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  val-
	      ues.   See  KEYWORD  SUBSTITUTION  below.   For example, for the
	      Revision keyword, generate  the  string  $Revision$  instead  of
	      $Revision:  1.6  $.  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 $Revi-
	      sion: 1.6 $ 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  ini-
	      tialize 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  1.6  instead  of
	      $Revision:  1.6  $.  This can help generate files in programming
	      languages where it is hard  to  strip  keyword  delimiters  like
	      $Revision: $  from a string.  However, further keyword substitu-
	      tion 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]
	      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  signifi-
	      cant).   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)	depen-
	      dency  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) revi-
	      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	corre-
	      spondents  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 ver-
	      sion 4 or earlier has a time stamp that  is  off	by  up	to  13
	      hours.   A  revision extracted while emulating version 4 or ear-
	      lier contains abbreviated dates of the  form  yy/mm/dd  and  can
	      also contain different white space and line prefixes in the sub-
	      stitution 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.


       $Author$
	      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 " * " pre-
	      fix  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.
	      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 possi-
       ble.  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.
       Manual Page Revision: 1.6; Release Date: 1999/08/27.
       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.

GNU				  1999/08/27				 CO(1)

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