We upgraded from Solarise9 to Red Hat 9. In Unix I used the command fuser -u filename.dat to see what user is holding a file. It showed the user and his ID
Jon (1234) Jon (5678)
In Linux the same command is used fuser -u filename.date,
but it shows all the files is being holded by root
root(1234) root(56789). I also tried to use lsof, but this also does not show the user.

Try ls -l <filename>.

Your fuser command is (or was) probably just an alias for this, since fuser is more commonly a command for mounting a file system in "user space,"

If your upgraded your system, perhaps the "real" fuser system was installed, and your fuser command mounted the data file as a file system. (I believe that it is possible to mount some types of files, e.g. iso and archive, as file systems using fuser.)

ls -l does not do what fuser -u filename did on my Unix server
Here is a example of what it looked like in Unix

APPX, Copyright (c) 1990-2004, APPX Software, Inc.
All Rights Reserved.


[ssc@appexsrv1 ssc]$ su - rooot
Password: [ssc@appexsrv1 ssc]$ su - root
Password:
[root@appexsrv1 root]# cd /usr/local/appxdata/DIV/ACC/Data
[root@appexsrv1 Data]# ls -l NEWVOTE.dat
-rw-r--r-- 1 appx appx 16393585 Feb 16 14:40 NEWVOTE.dat
[root@appexsrv1 Data]# fuser -u NEWVOTE.dat
NEWVOTE.dat: 3608(Jon) 3761(Jon)
[root@appexsrv1 Data]#

In Linux

[ssc@appexsrv1 ssc]$ su - root
Password:
[root@appexsrv1 root]# cd /usr/local/appxdata/DIV/ACC/Data
[root@appexsrv1 Data]# ls -l NEWVOTE.dat
-rw-r--r-- 1 appx appx 16393585 Feb 16 14:40 NEWVOTE.dat
[root@appexsrv1 Data]#


[ssc@appexsrv1 ssc]$ su - root
Password:
[root@appexsrv1 root]# cd /usr/local/appxdata/DIV/ACC/Data
[root@appexsrv1 Data]# ls -l NEWVOTE.dat
-rw-r--r-- 1 appx appx 16393585 Feb 16 14:40 NEWVOTE.dat
[root@appexsrv1 Data]# fuser -u NEWVOTE.dat
NEWVOTE.dat: 3608(root) 3761(root)
[root@appexsrv1 Data]#

Perhaps you could obtain the functionality you want with 'lsof'.

/usr/sbin/lsof | grep userid | grep filename

eg:

/usr/sbin/lsof | grep bomr | grep /bin/bash

This could be turned into a bash function or shell script, to allow passing the required arguments. The output could be cleaned up to suit your taste with filters such as 'sed'.

--- rod.


ps. My original interest in this thread was to do with the 'filesystem-in-userspace' fuse. You might consider the implications of using the name 'fuser' with any possible future conflicts.

fuser works fine for me in the way that you say that you want. I suspect that the root account really is the user id that has that file open. Try using fuser on a home directory of an account that is logged in (not root). I bet it will properly show the user account id.

Example: log on as Jon. Then as either Jon or root do fuser -u on the home directory of Jon. If Jon's home directory is /home/Jon then do this:

fuser -u /home/Jon