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I'm moving png files from source/ to dest/ with this:

mv /source/*.png /dest/

How can I change that command so I only move 10 png files?

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  • Specify the correct file name pattern, maybe? What about ls | head -10? Commented Dec 2, 2022 at 7:16
  • @U.Windl see Why not parse ls (and what to do instead)? Commented Dec 2, 2022 at 7:43
  • @cas I know how to do that correctly, but I wanted the OP to explain a bit more what he really wants to do, or what the real problem is. Commented Dec 2, 2022 at 7:47
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    so why suggest parsing ls? that's just irresponsible, especially if you claim to know better. Commented Dec 2, 2022 at 7:56

3 Answers 3

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You can do this in Zsh with a glob qualifier:

mv /source/*.png([1,10]) /dest/

Moves the first 10 ones in alphabetic order. You can pick a different order using the o/O/n qualifiers. For instance:

mv /source/*.png(OL[1,10]) /dest/

Would move the 10 largest ones.

An optimised version that selects the first 10 matches without bothering to sort can be done with the Y qualifier:

mv /source/*.png(Y10) /dest/
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POSIXly, that could be done with:

set -- /source/*.png [ "$#" -le 10 ] || shift "$(( $# - 10 ))" mv -- "$@" /dest/

Which would move the 10 last ones in alphabetic order.

Note that it excludes hidden ones and if there's no match, it would attempt to move a file called /source/*.png and likely fail.

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ls /source/*.png | head -n10 | xargs -I{} mv {} /dest/

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    This is only safe if you're using a recent version of GNU ls with the --zero option, combined with head -z -n 10, and xargs -0r .... And, since everything else relies on GNU versions, you may as well use GNU mv's -t option too. ls --zero /source/*.png | head -z -n 10 | xargs -0r mv -t dest/. Even so, it's still better to use find: find /source -maxdepth 1 -name '*.png' -print0 | head -z -n 10 | xargs -0r mv -t dest/. Commented Dec 2, 2022 at 7:43
  • @cas so using ls --zero avoids the problem of never parse ls? I have no idea about --zero and how that works but with your example I understood better. Commented Dec 2, 2022 at 16:13
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    @EdgarMagallon --zero is fairly new for GNU ls (first added as --null in July 2021, renamed to --zero a few days later. BTW, according to the changelog, "--zero also implies -1, -N, --color=none, --show-control-chars"). I wouldn't say "avoids the problem" - won't help at all for parsing metadata out of ls -l (that's what stat is for, anyway) but should be OK for just generating a list of NUL-separated files to pipe into other programs or read into an array with mapfile. Personally, I'll stick with using find, although the convenience of ls's sorting capabilities might be useful. Commented Dec 2, 2022 at 16:53
  • @cas thanks for the explanation! That's very clear and useful. I will take a look at the manuals too. As you said it'll be better keep using find or for in /somepath too Commented Dec 2, 2022 at 17:50

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