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bashls

ls with numeric range doesn't work inside bash script

I have a folder with files named as file_1.ext...file_90.ext. I can list a range of them with the following command:

$ ls /home/rasoul/myfolder/file_{6..19}.ext

but when I want to use this command inside a bash script, it doesn't work. Here is a minimal example:

#!/bin/bash

DIR=$1
st=$2
ed=$3

FILES=`ls ${DIR}/file\_\{$st..$ed\}.ext`
for f in $FILES; do
  echo $f
done

running it as,

$ bash test_script.sh /home/rasoul/myfolder 6 19

outputs the following error message:

ls: cannot access /home/rasoul/myfolder/file_{6..19}.ext: No such file or directory
Solution

  • Brace expansion happens before variable expansion.

    (Moreover, don't parse ls output.). You could instead say:

    for f in $(seq $st $ed); do 
    echo "${DIR}/file_${f}.ext";
done