LinuxQuestions.org - [SOLVED] Weird thing in redirecting stdout and stderr

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Weird thing in redirecting stdout and stderr

Hi... I'm trying to redirect the progress percentage of the mkisofs command to a zenity window... the thing is, mkisofs prints the xx% to the stderr... so what I'm trying to do is:

Code:

mkisofs options ../filename.iso . 2>&1 | grep done

and that "works"... I mean, it does print the correct lines on the terminal... however if a try to write to a file, or pipe it to another command, awk for example:

Code:

mkisofs options ../filename.iso . 2>&1 | grep done | awk '{print $1}'

it doesn't print anything...

Code:

mkisofs options ../filename.iso . 2>&1 | grep done > foo

this will make foo an empty file...

what am I doing wrong?

it is working, but the numbers are printed almos all at once at the end of iso building.

Might be line buffering by grep. Try to use grep --line-buffered

I had a similar issue and matir suggested the above.