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How do I print files in a directory with a numerical index preceding them?

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Peter Elbert

I’d like to print all files in a directory with a numbering, so that each file has a number before it, like this:

  1. myfile.txt
  2. anotherfile
  3. etc

I then want to refer to these files later on, like this:

mv 1 2 3 directory

How could I refer to the files by a numerical ordering?

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hr flag
steeldriver

You could put the filenames in an indexed array, and use the array indices, ex.

shopt -s nullglob
files=( * )

for i in ${!files[@]}; do 
  printf '%d. %s\n' $i "${files[i]}"
done

To refer to a file via its index n, use "${files[n]}", where n is evaluated as a numeric expression, ex. "${files[3]}" or n=3; echo "${files[n]}". Note that array indices in bash start from 0.

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in flag
Peter Elbert
What do ! and @ do, in the above?
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hr flag
steeldriver
@PeterElbert `${files[@]}` expands to a list of array values; whereas `${!files[@]}` expands to a list of the array's indices (or keys, in the case of an associative array). See the `Arrays` subsection under the `PARAMETERS` section of `man bash`.
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in flag
Peter Elbert
Thanks. Can I pass multiple indices to that file list? I’d like to conveniently move a bunch of files, like mv “${files[1, 2, 4:10, 22]}” directory. Or enter a live shell where I can just type “$ 1 2 4-10 directory”, without typing the “files”.
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hr flag
steeldriver
@PeterElbert you'd need to write a custom move command (shell function) that maps its arguments back to filenames I think (there's no way for the shell - or mv - to know that `1`, `2` and `4-10` are not filenames)
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