OK, so there's an easy workaround, but I'd like to understand what's going on:

I was wanting to try to diagnose a problem with kaffeine, so I attached an strace to its process, and redirected the output to a log file:

strace -p 19205 2>kaff.log

This worked fine, but produced an overwhelming amount of output, though, so I passed it through egrep to filter out the trivial (or continuous) output:

strace -p 19205 2>&1 | egrep -v '(^ioctl|^gettimeofday|^select|^read|^write|^poll)' > kaff.log

No output arrived in the file. However, if I remove the file redirection then I get the expected output whenever I click a button (or similar).

Thanks,
Rob

Works here ... which distro and what shell do you have that problem with?



Cheers,
Tink

The order of redirection statements makes a difference. Your command firstly tells the shell to send stderr to the same place that stdout is currently pointing to (usually the current terminal window). Then you tell stdout to go to the file, but stderr will still go where you originally sent it and is not changed by changing stdout afterwards. All you should need to do is:
I've assumed you're using the bash shell. There's more info on this in man bash if you search for redirection.