46 
root@host [/home2]# lsof /home2
COMMAND     PID     USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
php        3182 ctxmortg  cwd    DIR   8,17     4096 32858196 /home2/ctxmortg/public_html/hello
php        3182 ctxmortg    3r   REG   8,17    46404 55781766 /home2/ctxmortg/public_html/hello/cache/subprimemortgagemorgage.com/cache-zch-8284-cache.txt
php        3185 ctxmortg  cwd    DIR   8,17     4096 32858196 /home2/ctxmortg/public_html/hello
php        3185 ctxmortg    3r   REG   8,17     4185 35962154 /home2/ctxmortg/public_html/hello/cache/curl/http%3A%2F%2Fimage.yahoo.cn%2Fs%3Fq%3DNudity%26c%3D0%26s%3D%26page%3D277
php        3187 ctxmortg  cwd    DIR   8,17     4096 32858196 /home2/ctxmortg/public_html/hello
php        3187 ctxmortg    3r   REG   8,17    54640 69699731 /home2/ctxmortg/public_html/hello/cache/newdatingfriends.com/cache-zch-1545-cache.txt
php        3188 ctxmortg  cwd    DIR   8,17     4096 32858196 /home2/ctxmortg/public_html/hello
php        3188 ctxmortg    3r   REG   8,17    54640 21557063 /home2/ctxmortg/public_html/hello/cache/customersdeals.com/cache-zch-5715-cache.txt
php        3189 ctxmortg  cwd    DIR   8,17     4096 32858196 /home2/ctxmortg/public_html/hello
php        3189 ctxmortg    3r   REG   8,17     4185 36028071 /home2/ctxmortg/public_html/hello/cache/curl/http%3A%2F%2Fimage.yahoo.cn%2Fs%3Fq%3DVideos%26c%3D0%26s%3D%26page%3D329
php        3200 ctxmortg  cwd    DIR   8,17     4096 32858196 /home2/ctxmortg/public_html/hello
php        3200 ctxmortg    3r   REG   8,17    21036  9155614 /home2/ctxmortg/public_html/hello/cache/indorealestates.com/cache-zch-8562-cache.txt
lsof       3201     root  cwd    DIR   8,17     4096        2 /home2
lsof       3202     root  cwd    DIR   8,17     4096        2 /home2
webalizer 32342 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32342 ctxmortg    5uW  REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32360 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32360 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32361 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32361 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32362 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32362 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32363 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32363 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32364 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32364 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32365 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32365 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32366 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32366 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32367 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32367 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32368 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32368 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
webalizer 32369 ctxmortg  cwd    DIR   8,17     4096 32890953 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com
webalizer 32369 ctxmortg    5u   REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db
bash      32409     root  cwd    DIR   8,17     4096        2 /home2

I want to umount a drive but cannot.

So, what does cwd, 3r dir, and reg mean anyway?

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2
  • Ah, cPanel...
    – jordanm
    Commented Jan 6, 2013 at 5:42
  • 1
    man (8) lsof, in the Output section, will explain this all.
    – chromechris
    Commented Nov 24, 2016 at 21:03

3 Answers 3

Reset to default
57 
COMMAND     PID     USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
webalizer 32342 ctxmortg    5uW  REG   8,17    12288 32890954 /home2/ctxmortg/tmp/webalizer/eyebestdatedotcomauph.ctxmortgagemortgagerefi.com/dns_cache.db

FD - File Descriptor

If you are looking for file being written, look for following flag

# - The number in front of flag(s) is the file descriptor number of used by the process to associated with the file
u - File open with Read and Write permission
r - File open with Read permission
w - File open with Write permission
W - File open with Write permission and with Write Lock on entire file
mem - Memory mapped file, usually for share library

So 3r means webalizer has a descriptor number 3 associated with ...dns_cache.db, with read permission.

TYPE - File Type

In Linux, almost everything are files, but with different type.

REG - REGgular file, file that show up in directory
DIR - Directory

NODE

inode number in filesystem

You can find complete details in the man page.

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0
9

Information on the meanings of the columns can be found in the lsof(8) manpage. I will address the ones you are asking about specifically.

cwd => current working directory
3r  => file descriptor 3 opened for reading
DIR => directory
REG => regular file

In order to unmount the drive, you will likely need to stop your webserver, and kill the webalizer process (since it's usually a batch job ran from cron).

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1
  • 2
    Thanks jordanm. For those coming to this later: The crucial bit of information needed in addition to "in the lsof manpage" is that you want to look in the OUTPUT section (as I learned from chromechris's comment on the original question). It's a very large manpage!
    – Mars
    Commented Mar 17, 2020 at 14:31
4

In this scenario I usually use lsof in combination with ps to find out who is holding the device busy.

Let's take a example with a usb stick that was mounted as /media/disk-1

$> sudo umount /media/disk-1 
[sudo] password for cj: 
umount: /media/disk-1: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

So I then try to find out who is holding the device with lsof.

$> lsof | grep disk-1
bash       7822         cj  cwd       DIR       8,33      16384          1 /media/disk-1

And since column 2 is the pid holding we can get the name of that process with ps.

$> ps -A | grep 7822
7822 pts/1    00:00:00 bash

Now that bash comes from a terminal that was open in a dir on the device, so at this point I could either close or kill that terminal so the device would be free again.

Update I don't think I answered the question, but maybe it could be helpful for someone else so I leave it anyway.

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1
  • 4
    Nice, but lsof shows the process name in the first column. You don't need ps to get that. :)
    – Adambean
    Commented Dec 11, 2018 at 15:44

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