How to "grab" matching files from a lookup file in bash?

Question

I have a lookup file containing filenames. I also have a directory containing files, some of which have the names that correspond to some of the names in the directory.

How can I:

1. Move exact matching files to a new directory or
2. Remove non-matching files from the existing directory

Also, how can I do this recursively through a top-level directory and its subdirectories?

Answer 1

Perhaps something along the following lines:

sed -e 's;^.*$;\^&\$; list-of-names > list-of-patterns

rm $(find . -type f | grep -v -f list-of-patterns)

Be careful, this will surely break if the filenames contain spaces or characters that the shell considers special. Please check what this would delete before running it for real!

(There might be a way of sidestepping the pattern file, but off the top of my head I don't see it).

Answer 2

The following bash script (warning: untested!) moves files from under /directory/with/the/files to under /matched/files. Only files whose name (sans directory) is in /path/to/lookup.file are moved. Beware that if there are symbolic links to directories in /directory/with/the/files, they are traversed recursively as if they were directories themselves.

#!/bin/bash
shopt -s globstar
set -f; IFS=$'\n'
typeset -A filenames
for x in $(cat /path/to/lookup.file); do filenames[$x]=1; done
set +f; unset IFS
cd /directory/with/the/files
for x in ./**; do
  if [[ -d "$x/." ]]; then
    : # skip directories and symbolic links to directories
  elif [[ -n ${filenames[${x##*/}]} ]]; then
    # the file is matched, move it under /matched/files
    mkdir -p "/matched/files/${x%/*}"
    mv "$x" "/matched/files/$x"
  else
    # the file isn't matched
    :
  fi
done

Explanations:

• shopt -s globstar enables the ** glob to traverse directories recursively.
• set -f; IFS=$'\n' turns off globbing and sets newlines as the sole word delimiter, so that the unquoted command substitution $(cat /path/to/lookup/files) is split at newlines only.
• filenames is an associative array.
• for x in ./** takes care that $x always contains a directory part (this way ${x%/*} is the directory part of $x, with . for the toplevel directory), and does not begin with - (so it doesn't risk being treated as an option).
• ${x##*/} expands to the filename part of $x, i.e. $x without the directory part.