man co – Man page for co

June 1, 2007 – 1:43 am

CO

Section: User Commands (1)
Updated: 1995/06/01
Index
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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).
 

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.

–kkv

Generate keyword strings using the default form, e.g.
$Revision: 5.13 $

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: 5.13 $.

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: 5.13 $

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
5.13

instead of
$Revision: 5.13 $.

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.

–S

Turns on same user locks. When this is enabled the user cannot check out
the same file twice.

–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
“ * rq

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.

Manual Page Revision: 5.13; Release Date: 1995/06/01.

Copyright © 1982, 1988, 1989 Walter F. Tichy.

Copyright © 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.

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Index

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

KEYWORD SUBSTITUTION

FILE MODES

FILES

ENVIRONMENT

DIAGNOSTICS

IDENTIFICATION

SEE ALSO

LIMITS

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Related posts:

1. man rcsmerge – Man page for rcsmerge
2. man rlog – Man page for rlog
3. man rcsclean – Man page for rcsclean
4. man rcsfile – Man page for rcsfile
5. man prs – Man page for prs
6. man date – Man page for date
7. man get – Man page for get
8. man inncheck – Man page for inncheck
9. man host – Man page for host
10. man dmidecode – Man page for dmidecode