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.
Do no post-processing on the bytes being read or written.
Do not display headers indicating the source of the bytes dumped.
Also dump the requested file descriptor activity in any new child processes that are created.
Remove duplicate read/writes from the output. If you're looking at a tty with echo, you might want this.
Display a version string.
Display a help message.
/proc/*/fd
Not used but useful for the user to look at to get good file descriptor numbers.
None.
The following diagnostics may be issued on stderr:
An unknown error occurred 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.
ttysnoop(8)