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binW
Asked: 2011-06-17 01:49:52 +0800 CST

how to get output of a script/program into a file?

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I am compiling a program using make and want the output of make to be written to a file. I have tried using > operator like

make > build_log.txt

and using tee command like

make | tee build_log.txt

but the problem is that some of the ouput goes into the file but rest keeps appearing on the screen.

I can simply copy/paste the text from terminal into a file after running make but that is not a solution.

So my question is how do I save i.e redirect all the output to file so that it goes into file only without appearing on screen.

gnome-terminal

1 Answers

  1. Best Answer

    The text that is displayed in the terminal comes from the stderr stream (2). If you do just make > build_log.txt, only the stdout (1) stream is redirected to the build_log.txt file.

    • stdout is the standard output stream and has file descriptor number 1. This is the default stream being redirected in shells.
    • stderr is the standard error stream and has file descriptor number 2

    To redirect the stderr stream to that build_log.txt file too, use:

    make > build_log.txt 2>&1
    • make is executed and
      • the stdout stream is redirected (>) to build_log.txt
      • the stderr stream is redirected (2>) to the stdout stream (&1), which was redirected to build_log.txt

    The order is important, you cannot switch switch the redirection operators like make 2>&1 > build_log.txt.

    Alternative command:

    make 2>&1 | tee build_log.txt > /dev/null

    The redirection to /dev/null is needed to hide output, tee writes its input to build_log.txt and outputs it too.

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