Man page 1 : peekfd

peekfd - peek at file descriptors of running processes

peekfd [ -8 , --eight-bit-clean ] [ -n , --no-headers ] [ -f , --follow ] [ -d , --duplicates-removed ] [ -V , --version ] [ -h , --help ] pid [ fd ] [ fd ]

...

peekfd attaches to a running process and intercepts all reads and writes to file descriptors. You can specify the desired file descriptor numbers or dump all of them.

-8 Do no post-processing on the bytes being read or written.

-n Do not display headers indicating the source of the bytes dumped.

-c Also dump the requested file descriptor activity in any new child processes that are created.

-d Remove duplicate read/writes from the output. If you're looking at a tty with echo, you might want this.

-v Display a version string.

-h Display a help message.

/proc/*/fdNot used but useful for the user to look at to get good file descriptor numbers.

None.

The following diagnostics may be issued on stderr:

Error attaching to pid ... An unknown error occured while attempted to attach to a process.. you may need to be root.

Probably lots. Don't be surprised if the process you are monitoring dies.

Trent Waddington <>

R ttysnoop (8)