README.md

$ add-date-suffix access.log.2.gz
'access.log.2.gz' -> 'access.log-20170821.gz'

Use this script if you happen to forget to add dateext for logrotate:

tee /etc/logrotate.d/defaults <<EOF
dateext
compress
delaycompress
EOF

add-date-suffix.sh

#!/bin/sh
set -e
mv -nv "$1" $(echo $1 | sed -E "s/.[0-9]+/-$(date -r $1 +%F | sed s/-//g)/")