Shell – `xargs` with spaces in filenames

filenamesquotingshellxargs

I'm trying to list only non-image files, searching only in the most recent 500 files. So I run

ls -t | head -500 | file | grep -v 'image'

which isn't right: it displays a help message. Changing it to

ls -t | head -500 | xargs file | grep -v 'image'

I now sometimes get the output I want, but if the filename has spaces in it—for example Plutonian\ Nights\ -\ Sun\ Ra.mp3—then xargs will run file Plutonian, file Nights, etc.

How do I either help xargs see the spaces, or otherwise accomplish what I'm trying to accomplish?

Best Answer

Using xargs, it can be done in this way:

find . -type f -print0 | xargs -0 file | grep -v 'image'

But xargs is so yesterday. The cool kids use parallel today. Using parallel, it would be:

find . -type f | parallel file | grep -v 'image'

See. No use of -print0 and -0. parallel is really smart by itself.

UPDATE

For listing only the most recent 500 files, your command would be:

ls -1t | head -500 | parallel file {} | grep -v image

Important

In case your parallel is old and above syntax doesn't work, then install the new version of parallel as explained here: http://www.gnu.org/software/parallel/parallel_tutorial.html

Related Solutions

Shell – ny way to use xargs across a pipe

If I understand correctly, you want to fire up one instance flac … | lame … for each input line, and interpolate the input into the arguments to both commands.

Since you need xargs to start a pipeline, you need to make it start a program that's capable of creating pipelines, i.e. a shell.

inotifywait -m -r -q -e moved_to --format "%w%f" ~/test |
xargs -l sh -c 'flac -cd "$0" - | lame -b 320 - "/media/1tb/$0.mp3"'

Alternatively, have the calling shell read lines one by one and run the pipeline.

inotifywait -m -r -q -e moved_to --format "%w%f" ~/test |
while IFS= read -r file; do
  flac -cd "$file" - | lame -b 320 - "/media/1tb/$file.mp3"
done

Note that the format %w%f produces an absolute path, to which you're prepending /media/1tb and appending .mp3. If you want to strip off the directory part of the file in the lame command, change $file to ${file##*/}. If you want to strip off the extension, change $file to ${file%.*}. If you want to do both, you'll have to do it in two steps. If you want to reproduce the directory hierarchy under /media/1tb, you can use mkdir -p.

cd ~/test
inotifywait -m -r -q -e moved_to --format "%w%f" . |
while IFS= read -r file; do
  [ -f "$file" ] || continue; # skip directories and other special files
  dir=${file%/*}; file=${file##*/}
  mkdir -p "/media/1tb/$dir"
  flac -cd "$dir/$file" - | lame -b 320 - "/media/1tb/$dir/${file#.*}.mp3"
done

Linux – passing variables from ‘ls’ to ‘tar’ via ‘xargs’

ls -t | head -n 3 | xargs tar -cf t.tar

Works for me. Is there a reason you need the -I flag set?

Best Answer

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Shell – ny way to use xargs across a pipe

Linux – passing variables from ‘ls’ to ‘tar’ via ‘xargs’

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