Move oldest file via cron

Question

I've got two directories.

/application/inbox
/application/unresponsive

The application looks for *.txt files in the inbox and works with them. Periodically the application will save entries from these files into date-named (2009-07-31) files in the unresponsive folder.

I'd like to setup a cron job which works once a day to move the oldest file from the unresponsive box into the inbox, adding a *.txt extension so it's picked up by the application.

Answer 1

Untested, likely buggy:

#!/bin/sh

# last file in list sorted newest->oldest
OLDEST=$(ls -t /application/unresponsive | tail -1)

# make sure $OLDEST isn't empty string
if [ -n $OLDEST ]; then
    # quote in case of spaces and remove directory name
    mv "$OLDEST" /application/inbox/$(basename "$OLDEST").txt
fi

Answer 2

If you want it to work with files with spaces (more robust). You should loop over them and use the -nt (newest based on modified time) or -ot (oldest) comparison operator with a basic min/max algorithm. Here is an example from this excellent BashFAQ:

files=(*) newest=${f[0]}
for f in "${files[@]}"; do
  if [[ $f -nt $newest ]]; then
    newest=$f
  fi
done

So your example would be (untested):

files=(/application/inbox/*) oldest=${f[0]}
for f in "${files[@]}"; do
  if [[ $f -ot $oldest ]]; then
    oldest=$f
  fi
mv "$oldest" /application/unresponsive/
done

Learning how not to use the output of ls is better I think. Here is link to the argument why. But I leave it up to you to decide if that is true or just pseudo-unix-guru nonsense :-)