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Are some limitations of using tee functions?

  • Mar 11, 2025 3:21 AM UTC
  • 3 replies
  • 97 views
Pawel Kwiatkowski

E.g. I would like use subshell like $(date). Is it possible?

Best answer by Brendan Dalpe

Did a little digging on this. The native function does not spawn a shell, so subshells are not supported.

However, you can customize your tee function to start a new bash shell which will allow you to run a subshell command as you want.

354_55509e803f5540de97053b69ff067279.png

The file is written as expected:

354_fe05d02dec424ea9967aac3883bd55a7.png

Note: You might not see file timestamp rotation because we're keeping that shell open unless it exits for some reason. Just keep that in mind as you're building out the pipeline.

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    3 replies

    Hi @Pawel Kwiatkowski, can you describe the outcome you are trying to achieve? You should be able to use a subshell if the interpreter supports it.

    Pawel Kwiatkowski

    Hello @Brendan Dalpe
    I would like redirect output to a log, eg. /tmp/file_$(date "+%d%h%g").log
    When I was using this in the tee fun is not working as expected.

    I was trying using '-a' arg but also is not working.

    Did a little digging on this. The native function does not spawn a shell, so subshells are not supported.

    However, you can customize your tee function to start a new bash shell which will allow you to run a subshell command as you want.

    354_55509e803f5540de97053b69ff067279.png

    The file is written as expected:

    354_fe05d02dec424ea9967aac3883bd55a7.png

    Note: You might not see file timestamp rotation because we're keeping that shell open unless it exits for some reason. Just keep that in mind as you're building out the pipeline.

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