how to find who is holding the lock of a file in RCS

Question

Suppose I lock a file which is controlled by RCS

[root@host1:/etc/yp]# co -l group auto_home
RCS/group,v  -->  group
revision 1.6103 (locked)
done
RCS/auto_home,v  -->  auto_home
revision 1.4003 (locked)
done
[root@host1:/etc/yp]#

I see the files with ",v" generated in RCS directory

[root@host1:/etc/yp/RCS]# ls -lrth | tail -3
-r--r--r--   1 root     other        16M Feb 20 12:20 passwd,v
-r--r--r--   1 root     other       3.5M Feb 21 23:03 group,v
-r--r--r--   1 root     other       4.1M Feb 21 23:03 auto_home,v
[root@host1:/etc/yp/RCS]#

Can we determine who is holding the lock file? All of the admins use the "root" login for making the changes ( by sudo -s to become root)

If someone has already locked, I see the below message

[root@campyp:/etc/yp]# co -l group
RCS/group,v  -->  group
revision 1.6103 (locked)
writable group exists; remove it? [ny](n): ^C
RCS: Interrupt
RCS: Cleaning up.
[root@campyp:/etc/yp]#

Can we check who has locked the file?

Answer 1

No. If all your users are root, then the lock will always belong to root.

This is a dubious arrangement at best, anyway. Have users commit edits as themselves; there should be no sane reason to do these things as root in the first place.

Answer 2

In RCS, locks are stored in the header of the archive-file. Here is an example header to illustrate:

head    1.1;
access
        thomas;
symbols;
locks
        thomas:1.1; strict;
comment @# @;

1.1
date    2014.08.14.00.40.55;    author thomas;  state Exp;
branches;
next    ;

desc
@@

The rlog command gives that header information:

$ rlog 2linux,v

RCS file: 2linux,v
Working file: 2linux
head: 1.1
branch:
locks: strict
        thomas: 1.1
access list:
        thomas
symbolic names:
keyword substitution: kv
total revisions: 1;     selected revisions: 1
description:
----------------------------
revision 1.1    locked by: thomas;
date: 2014/08/14 00:40:55;  author: thomas;  state: Exp;
RCS_BASE
=============================================================================

By default, the author of a lock is determined by checking environment variables LOGNAME and USER. Those are set when your users sudo, e.g., to "root". But the behavior can be overridden:

• When you sudo, the original $USER is saved in SUDO_USER. One could reset $LOGNAME and $USER from $SUDO_USER, making locks correspond to the real users.
• RCS is documented to support setuid operation with the files owned by root. You may be able to use that, rather than having your users sudo.

Further reading:

• rlog(1)
• rcsfile(5)
• ci(1) (see discussion of setuid)