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I have example sub-directory names such as:

  • Test_ABCDEF_406_1
  • Test_ABCDEF_AOH_1
  • Test_ABCDEF_AUQ_1

within a larger directory called Test.

How can I efficiently pull out "ABCDEF_**_" or everything after Test_ to get the following:

  • ABCDEF_406_1
  • ABCDEF_AOH_1
  • ABCDEF_AUQ_1

Note that the above are folders and not files if that makes a difference.

MAtennis9
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1 Answers1

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You iterate over the pathnames of the subdirectories and use a parameter substitution to delete the initial part of them:

#!/bin/sh

for dirpath in Test/Test_*/; do
    # Because of the pattern used above, we know that
    # "$dirpath" starts with the string "Test/Test_",
    # and this means we know we can delete that:

    # But first delete that trailing /
    dirpath=${dirpath%/}

    shortname=${dirpath#Test/Test_}

    printf 'The shortened name for "%s" is "%s"\n' "$dirpath" "$shortname"
done

The substitution ${variable#pattern} is a standard substitution that will delete the (shortest) match of pattern from the start of the value $variable.

Likewise, ${variable%pattern}, used to delete the trailing / in the code, deletes the shortest match of pattern from the end of the value $variable.

Testing on the following directory tree:

.
`-- Test/
    |-- Test_ABCDEF_406_1/
    |-- Test_ABCDEF_AOH_1/
    `-- Test_ABCDEF_AUQ_1/

the code would produce

The shortened name for "Test/Test_ABCDEF_406_1" is "ABCDEF_406_1"
The shortened name for "Test/Test_ABCDEF_AOH_1" is "ABCDEF_AOH_1"
The shortened name for "Test/Test_ABCDEF_AUQ_1" is "ABCDEF_AUQ_1"
Kusalananda
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  • Isn't that syntax specific to `bash`? – Alexis Wilke Mar 18 '21 at 19:32
  • @AlexisWilke None of this is `bash`-specific. This would work on any shell that is aiming to be POSIX-compliant. `sh`, `bash`, `zsh`, `yash`, `ksh`, ... – Kusalananda Mar 18 '21 at 19:34
  • @Kusalananda So if I just wanted the output ABCDEF_406_1, ABCDEF_AOH_1, etc., do I just need to do: print $shortname ? – MAtennis9 Mar 18 '21 at 19:37
  • @ASinha You have the short name in `$shortname`, so you would output only that or do whatever it is that you actually want it for. I outputted a bit more to illustrate how to do it, but you could use `printf '%s\n' "$shortname"`, or just `echo "$shortname"` if you were sure that it would be safe (see https://unix.stackexchange.com/questions/65803). – Kusalananda Mar 18 '21 at 19:39
  • @Kusalananda great, that worked perfectly. Thank you! – MAtennis9 Mar 18 '21 at 19:42