Small snippets to remember that I use from time to time.

foreground_background.sh

[[ "$(ps -o stat= -p $PPID)" = "Ss" ]] && echo "Executed in foreground" || echo "Executed in background"
# credit : https://stackoverflow.com/questions/4261876/check-if-bash-script-was-invoked-from-a-shell-or-another-script-application

free_space.sh

echo -e "Use%\tAvail:\tMounted on:" ; df -hTP  | sort -nr -k6 | grep -P '\d%' | awk '{ printf $6 ; printf "\t" ; printf $5 ; printf "\t" ; print $7 }'

webm2thumbnails.sh

for i in `find . -name "*.webm" -print`; 
do 
  DIR=`dirname $i`;
  NAME=`basename $i`;
  ffmpeg -i $i -s 620x348 -ss 00:00:08.435 -vframes 1 ${DIR}/${NAME%.webm}.jpg;
done