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co(1)                                                                    co(1)


       co - check out RCS revisions


       co [options] file ...


       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


              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).

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

              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.

              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:
              1.1 $ 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

       -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:  1.1  $.  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: 1.1 $ 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  1.1  instead  of
              $Revision:  1.1  $.  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.

              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.

              quiet mode; diagnostics are not printed.

              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  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.

              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).

              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.

              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.

              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-
              sion numbers.  For the initial such pair, rev1 denotes the revi-
              sion  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  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 $Log$.

              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.


       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:

              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

              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

              The login name of the user who locked the revision (empty if not

       $Log$  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:
     $", 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:  $.

              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.

              char     escape sequence
              tab      \t
              newline  \n
              space    \040
              $        \044
              \        \\


       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.


       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: 1.1; Release Date: 1999/04/23.
       Copyright (C) 1982, 1988, 1989 Walter F. Tichy.
       Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.


       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.


       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                               1999/04/23                             co(1)

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