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Old 04-09-2010, 08:19 AM   #1
Registered: Jul 2009
Posts: 94

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Question strace -f -p pid_no > trace.txt 2>&1

I was given the above command to trace one of the java processes which was failing with an outofmemory exception.

Based on man I under stand what -f and -p stand for. I also understand redirect output to trace.txt. But I am not clear on what '2>&1' is for. This has successfully run and helped me debug some issues. Can somebody explain what is the significance of '2>&1' is?

Old 04-09-2010, 08:28 AM   #2
Registered: Feb 2008
Location: Texas
Distribution: Fedora, RHEL, CentOS
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2 is stderr, 1 is stdout

you are effectively saying send/redirect stderr (2) to the same location as stdout (1)

All About Redirection

you might also be interested in the use of strace's output to a file option...

strace -f -p pid_no -o trace.txt

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Old 04-09-2010, 09:47 AM   #3
Registered: Jul 2009
Posts: 94

Original Poster
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Thanks for helping understand redirection. Also the second command is easier to remember


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