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I've got a directory with numbered files, e.g. 1_foo.txt 2_bar.asc 13_test.png, and want to move them into individual directories (e.g. 1, 2 and 13) using as simple a bash command as possible.

Creating the numbered directories was easy:

mkdir $(seq 1 15)

I've also come up with a command to copy the files into their respective directories:

seq 15 -1 1 | xargs -I@ mv @_* @

That doesn't work, though, as the * is interpreted as a normal character when used with xargs, giving me errors like "mv: File '15_*' not found.".

Is there any easy way to use * as a wildcard in a command called by xargs?

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up vote 11 down vote accepted

You were very close.

seq 15 -1 1 | xargs -I@ sh -c "mv @_* @"

You need to delay the interpretation (expansion) of the * until after the @ substitution has occurred.  (But you already understood that that was the problem, right?)

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Thanks, that worked perfectly. I'll vote your answer up as soon as I've got enough reputation to do that. – Dec 13 '12 at 19:48

Just don't use xargs for that. Use a for loop:

for i in $(seq 1 15); do
    mv ${i}_* $i

Even better is to use brace expansion instead of seq:

mkdir {1..15}

for i in {1..15}; do
    mv ${i}_* $i
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You're right, that's definitely more elegant than using xargs. Thanks for telling me about brace expansion. – Dec 13 '12 at 19:50

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