Looking at the manpage for lsof, it seems to have a large selection of commands and modes in which to run it. If I were you, I would try opening it with IPC::Open3 and see what you can do with it that way. IPC::Open3 will allow you to separate the STDOUT and STDERR, so after you send lsof a command you could read the STDOUT and STDERR and try to detect your corruption problem. There are alot of advanced techniques you can use with IPC::Open3 like adding the STDOUT and STDERR to IO::Select, and using low level ioctl to see which filehandles have output, (see which filehandles have output from perldoc -q filehandle ) for your ftp problem.