How can I redirect OS X dtruss output when running with sudo?

Question

I'm running dtruss on Mac OS X 10.9. Simple example is:

sudo -c ls

But I'd like to capture the dtruss output into a file. I saw something that suggests that I can do something like:

sudo bash -c 'dtruss -c ls >x'

but when I do this the output of dtruss still goes to the terminal and the list of file from ls gets redirected to the file.

How can I redirect the output of dtruss to a file?

dtruss probably writes to `stderr` instead of `stdout` witch is what `>x` captures. This questions explains what to do: [Linux less behavior and stderr](http://superuser.com/questions/366596/linux-less-behavior-and-stderr) — Nifle, Jul 08 '14 at 15:05

Luke Quinane · Answer 1 · 2015-03-08T00:26:55.570

9

I've been running it like this:

sudo dtruss -f -p 12345 2> /tmp/trace.txt

-f says to follow child processes.
-p specifies which process ID to trace.
12345 is a placeholder for a process ID. You could get that by looking at top or ps -A.
2> pipes standard error into the output file. For some reason dtruss outputs everything on stderr.

edited Mar 08 '15 at 00:26

answered Mar 06 '15 at 01:07

Luke Quinane

Could you expand your answer to explain what this does? Thanks. – fixer1234 Mar 06 '15 at 04:47
'-f' says follow child processes, '-p' specifies which process ID to trace, '2>' pipes standard error into the output file. For some reason dtruss outputs everything on stderr. – Luke Quinane Mar 06 '15 at 05:17
Is 12345 a placeholder for the process ID (and where would that come from)? – fixer1234 Mar 06 '15 at 05:23
It is a placeholder for a process ID. You could get that by looking at `top` or `ps -A`. – Luke Quinane Mar 06 '15 at 06:50

1 Answers1