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?

If the user is logged in as root when they lock the file, then root has the lock. If you are logged in as root, then you have the lock. This is why doing things like this as root is a *really* bad idea! — William Pursell, Feb 23 '16 at 02:11

Thomas Dickey · Answer 1 · 2016-02-23T01:17:04.110

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.

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

2 Answers2