Less known Solaris Features...

fuser

fusers enables you to look for the processes that access a directory or a file. For example we can check for all processes using the / filesystem as their "working filesystem":

# fuser -c /
/: 701ctm 676ctm 675ctom 672ctom 596ctm 592ctm 585ctm 584ctom 581ctom 568ctm 523ctom 521ctom 481ctom 478ctom 477ctom 469ctom 456ctom 437ctom 425ctm 418ctom 412ctom 402ctom 401ctom 399ctom 380ctom 379ctom 366ctm 345ctom 341ctom 338ctom 333ctom 332ctom 319ctom 272ctom 262ctom 153ctm 140ctm 133ctom 131ctom 125ctm 100ctom 18ctm 9ctom 7ctom 1ctm

I´m sure you alread assume, that the numbers stand for the process id´s. But what does all that letters mean. I will cite the manpage for this:

• c: Indicates that the process is using the file as its current directory.
• m: Indicates that the process is using a file mapped with mmap(2).
• n: Indicates that the process is holding a non-blocking mandatory lock on the file.
• o: Indicates that the process is using the file as an open file.
• r: Indicates that the process is using the file as its root directory.
• t: Indicates that the process is using the file as its text file.
• y: Indicates that the process is using the file as its controlling terminal.

But fuser can do more for you

Okay, now you know which processes uses a filesystem. But let´s assume you have to unmount a filesystem for maintaining the storage. But there are still some users, who didn´t read their mails and you can´t unmount it.


# cd /mnt/application
# sleep 1000&
[1] 691
# sleep 1000&
[2] 692
# cd /
# umount /mnt/application
umount: /mnt/application busy

Dammit ... Okay, let´s check for the offending processes:

fuser -u /mnt/application
/mnt/application: 692c(root) 691c(root)

And now comes the kicker: fuser can kill all processes using a certain file or directory. You warned your users ...

# fuser -k -u /mnt/application
/mnt/application: 692c(root) 691c(root)
[2]+ Killed sleep 1000 (wd: /mnt/application)
(wd now: /)
[1]+ Killed sleep 1000 (wd: /mnt/application)
(wd now: /)
#

Now we can unmount the directory:

# umount /mnt/application
#

A neat trick with fuser

Okay, working with PID may a little bit cumbersome. Pete Shanahan posted a neat trick a long time ago. Let´s assume the example with the both sleep processes. You´ve remounted the filesystem an started some programs while beeing in the /mnt/application filesytem:

# cd /mnt/application
# sleep 1000&
[1] 726
# sleep 1000&
[2] 727
# cd /
# ps -o pid,args -p "$(fuser /mnt/application 2>/dev/null)"
PID COMMAND
726 sleep 1000
727 sleep 1000
#

Do you want to learn more ?

docs.sun.com: fuser(1M)
Pete Shanahan´s fuser trick