How can a process intercept stdout and stderr of another process on Linux?

Question

I have some scripts that ought to have stopped running but hang around forever. Is there some way I can figure out what they\'re writing to STDOUT and STDERR in a readable

Answer 1

GDB method seems better, but you can do this with strace, too:

$ strace -p  -e write=1 -s 1024 -o file

Via the man page for strace:

   -e write=set
               Perform a full hexadecimal and ASCII dump of all the
               data written to file descriptors listed in the spec-
               ified  set.  For example, to see all output activity
               on file descriptors 3 and 5 use -e write=3,5.   Note
               that  this is independent from the normal tracing of
               the write(2) system call which is controlled by  the
               option -e trace=write.

This prints out somewhat more than you need (the hexadecimal part), but you can sed that out easily.