Debugging under Linux.

ltrace.
strace.
lsof.
htop.
systemtap.

ltrace.

http://www.ltrace.org/: home page
https://sourceforge.net/projects/ltrace/: SourceForge home page
http://en.wikipedia.org/wiki/Ltrace: Wikipedia page.

strace.

$ strace -o $CMD.log -e trace=open,close $CMD

See:

http://en.wikipedia.org/wiki/Strace: Wikipedia home page.

lsof.

htop.

systemtap.

http://en.wikipedia.org/wiki/SystemTap: Wikipedia home page.