How to move files that are not in use?

Question

I want to move files in a directory that are not currently in use. I have a sense that some combination of lsof, find, and xargs could work but I can't quite get there. So far, I created the following command:

lsof mydir/*|awk '(NR>1){print $9}

This gives me a list of files that ARE being used. If I could just get a list of files that are NOT being used, then something like xargs could issue a mv on those files. I just can't seem to find an elegant way of doing this. Does anyone have any hints for me?

Answer 1

I'd do it this way.

find $dir -maxdepth 1 | sort > $other_dir/all_files
lsof $dir/* | awk '(NR>1) {print $9}' | sort > $other_dir/in_use_files
comm -2 -3 $other_dir/all_files $other_dir/in_use_files

From comm(1):

NAME
       comm - compare two sorted files line by line

SYNOPSIS
       comm [OPTION]... FILE1 FILE2

    ...

       -2     suppress lines unique to FILE2

       -3     suppress lines that appear in both files

Now it's a simple matter of reformatting into a series of mv statements. Perhaps like this:

while IFS= read file ; do
    mv "$file" "$destination/"
done < <(comm -2 -3 all_files in_use_files)

Or using another intermediate file if you prefer.

Answer 2

Perhaps not the best way, but one can just code it up in a few minutes:

get your list of open files (sort if not already)

get a list of all files (sort if not already)

diff the two lists

xargs whatever

The number of steps here will make obvious something that should have been a concern anyway, which is race conditions - the files that are in use when you select them may not be the files that are in use when you actually move them.

Answer 3

Thanks to @Sorpigal's suggestion, I found an easy way to make this work without loops:

comm -2 -3 <(find $dir -maxdepth 1 -type f|sort) <(sudo lsof $dir/* | awk '(NR>1) {print $9}'|sort) | xargs -I {} mv {} $move_dir

I'm not sure of race conditions but it doesn't matter in my case. The files are opened once for writing and then should be closed until moved.