Example file for compressing .fits files while maintaining modification date and file name

fcompress

#!/bin/bash
# Compress a FITS file while preserving its name and date
#
# Can be used as follows:
#
#  find . -name "*.fits" -mtime +30 -exec fcompress {} \;
#
# Note that fpack will not recompress file already compressed, 
# maybe that is good enough, but we also set a file attribute
# in case we need to test that in future for efficiency reasons.
set -e # Exit on error
tstamp=`date -r $1  +%Y%m%d%H%M.%S`
before=`stat -c%s $1`
fpack -F -g2 $1
attr -q -s user.fpack -V true $1
touch -t $tstamp $1
after=`stat -c%s $1`
if (($after < $before)); then
   compression=`echo "scale=2; 100*$after/$before" | bc`
   echo $1 $compression%
fi