


CO(1)                    USER COMMANDS                      CO(1)



NAME
     co - check out RCS revisions

SYNOPSIS
     co [_o_p_t_i_o_n_s] _f_i_l_e ...

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 FILE NAMING 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., com-
     piling)  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  may  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  may  be
     attached  to  any  of the options -f, -I, -l, -p, -q, -r, or
     -u.  The options -d (date),  -s  (state),  and  -w  (author)
     retrieve from a single branch, the _s_e_l_e_c_t_e_d 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 key-
     word substitution (see below).

OPTIONS
     -r[_r_e_v]
          retrieves the latest revision whose number is less than
          or  equal to _r_e_v. If _r_e_v indicates a branch rather than
          a revision, the  latest  revision  on  that  branch  is
          retrieved.   If  _r_e_v is omitted, the latest revision on



GNU                  Last change: 1990/12/04                    1






CO(1)                    USER COMMANDS                      CO(1)



          the default branch (see the -b  option  of  rcs(1))  is
          retrieved.   A  revision  is  composed  of  one or more
          numeric or symbolic fields separated by  periods.   The
          numeric  equivalent  of  a  symbolic field is specified
          with the -n option of the commands ci(1) and rcs(1).

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

     -u[_r_e_v]
          same as -r, except that it unlocks the retrieved  revi-
          sion  if  it was locked by the caller.  If _r_e_v is omit-
          ted, -u retrieves the latest  revision  locked  by  the
          caller; if no such lock exists, it retrieves the latest
          revision on the default branch.

     -f[_r_e_v]
          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:  5.4 $ 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: 5.4 $.  This option is
          useful to ignore differences due to  keyword  substitu-
          tion when comparing different revisions of a file.

     -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: 5.4 $ if that is how the
          string appeared when the file was checked in.  This can
          be  useful for binary file formats that cannot tolerate
          any changes to substrings that happen to take the  form
          of keyword strings.

     -kv  Generate only keyword values for keyword strings.   For
          example,  for the Revision keyword, generate the string
          5.4 instead of $Revision: 5.4 $.  This  can  help  gen-
          erate  files  in programming languages where it is hard
          to strip keyword delimiters like  $Revision: $  from  a



GNU                  Last change: 1990/12/04                    2






CO(1)                    USER COMMANDS                      CO(1)



          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  com-
          bined  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[_r_e_v]
          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[_r_e_v]
          quiet mode; diagnostics are not printed.

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

     -d_d_a_t_e
          retrieves the latest revision on  the  selected  branch
          whose  checkin date/time is less than or equal to _d_a_t_e.
          The date and time may be given  in  free  format.   The
          time  zone  LT stands for local time; other common time
          zone names are understood.  For example, the  following
          _d_a_t_es are equivalent if local time is January 11, 1990,
          8pm Pacific Standard Time (eight hours west of GMT):

               8:00 pm lt
               4:00 AM, Jan. 12, 1990           note: default is GMT
               1990/01/12 04:00:00              RCS date 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
               Fri-JST, 1990, 1pm Jan 12
               12-January-1990, 04:00-WET

          Most fields in the date and time may be defaulted.  The
          default  time  zone  is  GMT.   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 pro-
          vided  field,  the  time  zone's  current  values   are
          assumed.  For all other omitted fields, the lowest pos-
          sible values are assumed.  For example,  the  date  20,
          10:30  defaults  to 10:30:00 GMT of the 20th of the GMT
          time zone's current month and year.  The date/time must
          be quoted if it contains spaces.




GNU                  Last change: 1990/12/04                    3






CO(1)                    USER COMMANDS                      CO(1)



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

     -w[_l_o_g_i_n]
          retrieves the latest revision on  the  selected  branch
          which was checked in by the user with login name _l_o_g_i_n.
          If the argument _l_o_g_i_n is omitted, the caller's login is
          assumed.

     -j_j_o_i_n_l_i_s_t
          generates a new revision which is the join of the revi-
          sions  on _j_o_i_n_l_i_s_t. This option is largely obsoleted by
          rcsmerge(1) but is retained for  backwards  compatibil-
          ity.

          The _j_o_i_n_l_i_s_t is a comma-separated list of pairs of  the
          form  _r_e_v_2:_r_e_v_3,  where  _r_e_v_2 and _r_e_v_3 are (symbolic or
          numeric) revision numbers.  For the initial such  pair,
          _r_e_v_1 denotes the revision selected by the above options
          -f, ..., -w.  For all other  pairs,  _r_e_v_1  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 _r_e_v_1  and  _r_e_v_3  with
          respect  to  _r_e_v_2.  This  means  that  all changes that
          transform _r_e_v_2 into _r_e_v_1 are applied to a copy of _r_e_v_3.
          This  is  particularly  useful if _r_e_v_1 and _r_e_v_3 are the
          ends of two branches that have _r_e_v_2 as a common  ances-
          tor.   If  _r_e_v_1<_r_e_v_2<_r_e_v_3  on  the same branch, joining
          generates a new revision which is like _r_e_v_3,  but  with
          all  changes  that  lead  from _r_e_v_1 to _r_e_v_2 undone.  If
          changes from _r_e_v_2 to _r_e_v_1  overlap  with  changes  from
          _r_e_v_2  to  _r_e_v_3,  co  prints  a warning and includes the
          overlapping   sections,   delimited   by   the    lines
          <<<<<<< _r_e_v_1, =======, and >>>>>>> _r_e_v_3.

          For the initial pair, _r_e_v_2 may be omitted.  The default
          is  the common ancestor.  If any of the arguments indi-
          cate branches, the latest revisions on  those  branches
          are  assumed.   The  options  -l  and -u lock or unlock
          _r_e_v_1.

     -V_n  Emulate RCS version _n, where _n may be 3, 4, or 5.  This
          may  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 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  will  lose  its



GNU                  Last change: 1990/12/04                    4






CO(1)                    USER COMMANDS                      CO(1)



          default  branch.   An RCS revision generated while emu-
          lating version 4 or earlier will have a timestamp  that
          is  off  by up to 13 hours.  A revision extracted while
          emulating version 4 or earlier will  contain  dates  of
          the  form  _y_y/_m_m/_d_d  instead of _y_y_y_y/_m_m/_d_d and may also
          contain different white space in the  substitution  for
          $Log$.

KEYWORD SUBSTITUTION
     Strings of the form $_k_e_y_w_o_r_d$ and $_k_e_y_w_o_r_d:...$ embedded  in
     the   text   are   replaced   with   strings   of  the  form
     $_k_e_y_w_o_r_d:_v_a_l_u_e$ where _k_e_y_w_o_r_d and  _v_a_l_u_e  are  pairs  listed
     below.   Keywords may be embedded in literal strings or com-
     ments to identify a revision.

     Initially, the user enters strings of  the  form  $_k_e_y_w_o_r_d$.
     On  checkout,  co replaces these strings with strings of the
     form $_k_e_y_w_o_r_d:_v_a_l_u_e$.  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 sub-
     stitution 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 (GMT) the revision was checked in.

     $Header$
          A standard header containing the full pathname  of  the
          RCS  file,  the  revision  number,  the date (GMT), 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 (GMT).   Existing  log
          messages  are  _n_o_t replaced.  Instead, the new log mes-
          sage is inserted after $Log:...$.  This is  useful  for
          accumulating a complete change log in a source file.

     $RCSfile$



GNU                  Last change: 1990/12/04                    5






CO(1)                    USER COMMANDS                      CO(1)



          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).

FILE NAMING
     Pairs of RCS files and working files  may  be  specified  in
     three 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 _p_a_t_h_1/_w_o_r_k_f_i_l_e,v and the work-
     ing file name is of the form _p_a_t_h_2/_w_o_r_k_f_i_l_e where _p_a_t_h_1/ and
     _p_a_t_h_2/  are (possibly different or empty) paths and _w_o_r_k_f_i_l_e
     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  _p_a_t_h_1/  and  the
     suffix ,v.

     3) Only the working file is given.  Then co looks for an RCS
     file  of  the  form _p_a_t_h_2/RCS/_w_o_r_k_f_i_l_e,v or _p_a_t_h_2/_w_o_r_k_f_i_l_e,v
     (in this order).

     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 -kv is set or the file is  checked  out
     unlocked and locking is set to strict (see rcs(1)).





GNU                  Last change: 1990/12/04                    6






CO(1)                    USER COMMANDS                      CO(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.

DIAGNOSTICS
     The RCS file name, the working file name, and  the  revision
     number  retrieved are written to the diagnostic output.  The
     exit status is zero if and only if all operations were  suc-
     cessful.

IDENTIFICATION
     Author: Walter F. Tichy.
     Revision Number: 5.4; Release Date: 1990/12/04.
     Copyright 8c9 1982, 1988, 1989 by Walter F. Tichy.
     Copyright 8c9 1990 by Paul Eggert.

SEE ALSO
     ci(1),  ctime(3),  date(1),  ident(1),  rcs(1),  rcsdiff(1),
     rcsintro(1), rcsmerge(1), rlog(1), rcsfile(5)
     Walter  F.  Tichy,  RCS--A  System  for   Version   Control,
     _S_o_f_t_w_a_r_e--_P_r_a_c_t_i_c_e & _E_x_p_e_r_i_e_n_c_e 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.

BUGS
     The -d option sometimes gets confused, and accepts  no  date
     before 1970.
















GNU                  Last change: 1990/12/04                    7



