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UNIX in a Nutshell: System V Edition

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The RCS Utility
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rcs [




An administrative command for setting up or changing the default attributes of RCS files. Among other things, rcs lets you set strict locking ( -L ), delete revisions ( -o ), and override locks set by co ( -l and -u ). RCS files have an access list (created via -a ); anyone whose username is on the list can run rcs . The access list is often empty, meaning that rcs is available to everyone. In addition, you can always invoke rcs if you own the file, if you're a privileged user, or if you run rcs with -i . rcs accepts the standard options -q , -V , and -x .


-a users

Append the comma-separated list of users to the access list.

-A otherfile

Append otherfile 's access list to the access list of files .

-b[ R ]

Set the default branch to R or, if R is omitted, to the highest branch on the trunk.

-c' s '

The comment character for $Log keywords is set to string s . By default, co expands embedded $Log keywords into comments preceded by # . You could, for example, set s to .\" for troff files or set s to * for C programs. (You would need to manually insert an enclosing /* and */ before and after $Log .)

-e[ users ]

Erase everyone (or only the specified users ) from the access list.


Create (initialize) an RCS file but don't deposit a revision.


Interactive mode; prompt user even when standard input is not a terminal. (New in RCS Version 5.)

-k c

Use c as the default style for keyword substitution. (See co for values of c .) -kkv restores the default substitution style; all other styles create incompatibilities with RCS Version 4 or earlier.

-l[ R ]

Lock revision R or the latest revision. -l "retroactively locks" a file and is useful if you checked out a file incorrectly by typing co instead of co -l .


Turn on strict locking (the default). This means that everyone, including the owner of the RCS file, must use co -l to edit files. Strict locking is recommended when files are to be shared. (See -U .)

-m R : msg

Use the msg string to replace the log message of revision R . (New in RCS Version 5.6.)

-n flags

Add or delete an association between a revision and a name. flags can be:

name : R

Associate name with revision R .

name :

Associate name with latest revision.


Remove association of name .

-N flags

Same as -n but overwrite existing names .

-o R_list

Delete (outdate) revisions listed in R_list . R_list can be specified as: R1 , R1 - R2 , R1 - , or - R2 . When a branch is given, -o deletes only the latest revision on it. RCS Version 5.6 has changed the range separator character to : , although - is still valid.

-s state [ : R ]

Set the state of revision R (or the latest revision) to the word state .

-t[ file ]

Replace RCS file description with contents of file or, if no file is given, with standard output.

-t- string

Replace RCS file description with string .

-u[ R ]

The complement of -l : unlock a revision that was previously checked out via co -l . If someone else did the check out, you are prompted to state the reason for breaking the lock. This message is mailed to the original locker.


Turn on non-strict locking. Everyone except the file owner must use co -l to edit files. (See -L .)


Associate the label To_customer with the latest revision of all RCS files:

rcs -nTo_customer: RCS/*

Add three users to the access list of file beatle_deals :

rcs -ageorge,paul,ringo beatle_deals

Delete revisions 1.2 through 1.5:

rcs -o1.2-1.5 doc

Replace an RCS file description with the contents of a variable:

echo "$description" | rcs -t 


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