Tip: Find open files w/o lsof

Contents

1. Find device and Inode of a library or binary
2. Search for jfs2.<Major>.<Minor>.<Inode> under /proc
3. Find processes of the PIDs

This small article describes how to find all processes using a specific file (binary, lib, etc) without addons like lsof.

# istat /usr/lib/libssh2.a
Inode 12880 on device 10/9      File
Protection: rwxr-xr-x
Owner: 0(root)          Group: 0(system)
Link count:   1         Length 572979 bytes

Last updated:   Tue Oct 22 15:01:13 CEST 2013
Last modified:  Fri Jun 21 23:43:08 CEST 2013
Last accessed:  Tue May 27 12:01:54 CEST 2014

From the above output we read the information we need for the next step:

• Device Major: 10
• Device Minor: 9
• Inode: 12880

# find /proc/*/object -name "jfs2.10.9.12880"
/proc/4194450/object/jfs2.10.9.12880
/proc/5111820/object/jfs2.10.9.12880
/proc/6095050/object/jfs2.10.9.12880
/proc/7077940/object/jfs2.10.9.12880
/proc/7405804/object/jfs2.10.9.12880

Conclusion: The library /usr/lib/libssh2.a is currently in use by 5 processes with the PIDs 4194450, 5111820, 6095050, 7077940 und 7405804.

# for p in 4194450 5111820 6095050 7077940 7405804 ; do ps -fp $p ; done
     UID      PID     PPID   C    STIME    TTY  TIME CMD
  apache  4194450  6095050   0   Mar 04      -  6:53 /opt/freeware/sbin/httpd -k start
     UID      PID     PPID   C    STIME    TTY  TIME CMD
  apache  5111820  6095050   0   Mar 04      -  6:49 /opt/freeware/sbin/httpd -k start
     UID      PID     PPID   C    STIME    TTY  TIME CMD
    root  6095050        1   0   Mar 04      -  1:51 /opt/freeware/sbin/httpd -k start
     UID      PID     PPID   C    STIME    TTY  TIME CMD
  apache  7077940  6095050   0   Mar 04      -  6:54 /opt/freeware/sbin/httpd -k start
     UID      PID     PPID   C    STIME    TTY  TIME CMD
  apache  7405804  6095050   0   Mar 04      -  7:02 /opt/freeware/sbin/httpd -k start

In the above example the libraries are all opened by the Apache webserver.