I have the following bash loop.

for file in /home/directory/*; do
echo "$filename"
##execute command here with $filename

How can I select only certain files? For example, only selecting files without "mask" in their filename, e.g. test-file.zip. Additionally in each loop iteration I want do declare a variable with a "mask" added, i.e. test-file-mask.zip. How can I do this?


I think I have to be more precise. ;) So I have a folder with lots of files, for example


That means for each file, there is also a "mask" file. Now I want in each loop iteration to select both the file without mask and the file with mask. For example in the first loop iteration $file should point to test_001.nii.gz and $mask should point to test_001-mask.nii.gz and in the second loop iteration $file should point to test_002.nii.gz and $mask to test_002-mask.nii.gz etc.

  • I'm confused which one of the mentioned things this question is actually about. What do you mean by "declare a variable"? Would the file "masked-gentleman.zip" be selected by your criteria? – Anko May 13 '15 at 9:56
  • I have edited the description – machinery May 13 '15 at 10:29

Using find and sed:

find /home/directory/* -type f -name '*.gz' \
-not -name '*mask*' | while IFS= read -r file; do

    mask="$(sed 's/^\([^.]*\)/\1-mask/' <<<"$file")"


Consider any directory name does not contain the string mask.

| improve this answer | |
  • Thank you for your answer. I have an additional problem. I want a variable $brain which should be equal to $file but the directory should be different. E.g. when $file is /home/directory/test.nii.gz then $brain should be /home/new_directory/test.nii.gz How can this be achieved? – machinery May 13 '15 at 17:10
  • @Thomas: Use brain="$(sed 's:^\(/[^/]\+/\)\([^\]\+\):\1new_\2:'<<<"$file")" – heemayl May 13 '15 at 17:32

In [[ ... ]], the right hand side of a == can be a pattern:

for file in /home/directory/* ; do
    if [[ $file != *-mask.nii.gz ]] ; then
        echo "$filename" "$mask"
| improve this answer | |
  • Note that in bash-4.3.tar.gz, $extension above would be 3.tar.gz – Stéphane Chazelas May 13 '15 at 10:06
  • @StéphaneChazelas: Yes. But if the desired extension is tar.gz, the problem is very hard :-) – choroba May 13 '15 at 10:07
  • @choroba I have update the description, see above – machinery May 13 '15 at 10:29
  • @Thomas: I've updated the answer. – choroba May 13 '15 at 11:09

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