Lsof

From Liki

lsof is a *nix command for listing open files. An excellent tutorial to using it for all kinds of useful things is here.

For example, if you want to know where the locate command keeps it's database

locate a > /dev/null & sudo lsof -p `jobs -p %1`

First we need to have `locate' running for a while. `locate a > /dev/null' will list all files with `a' in their path (quite a few of them :p). We pipe all this output to /dev/null, since we don't care about it and use the ampersand to background the process. With locate running in the backround (as job 1), we can get it's process ID with `jobs -p %1`, and use that PID with `lsof' (sudoing to get priveledges), to list all of locates open files.

The output on my Ubuntu machine looks like

COMMAND   PID  USER   FD   TYPE DEVICE    SIZE    NODE NAME
locate  27630 wking  cwd    DIR    8,1   12288 1818626 /home/wking
locate  27630 wking  rtd    DIR    8,1    4096       2 /
locate  27630 wking  txt    REG    8,1   31308 9241558 /usr/bin/slocate
locate  27630 wking  mem    REG    8,1   38420  229462 /lib/tls/i686/cmov/libnss_files-2.6.1.so
locate  27630 wking  mem    REG    8,1   34352  229466 /lib/tls/i686/cmov/libnss_nis-2.6.1.so
locate  27630 wking  mem    REG    8,1   83712  229453 /lib/tls/i686/cmov/libnsl-2.6.1.so
locate  27630 wking  mem    REG    8,1   30436  229458 /lib/tls/i686/cmov/libnss_compat-2.6.1.so
locate  27630 wking  mem    REG    8,1 1339816  229403 /lib/tls/i686/cmov/libc-2.6.1.so
locate  27630 wking  mem    REG    8,1  109148  229389 /lib/ld-2.6.1.so
locate  27630 wking    0u   CHR  136,0               2 /dev/pts/0
locate  27630 wking    1w   CHR    1,3            9399 /dev/null
locate  27630 wking    2u   CHR  136,0               2 /dev/pts/0
locate  27630 wking    3r   REG    8,1 9940978 5096068 /var/lib/slocate/slocate.db

So the database is /var/lib/slocate/slocate.db