For example in a bash script you need to delete one or more word from the string , you can use sed to do just that
sed -e "s/word to delete//g"
sed is searching for “word to delete” and replacing it with nothing ,
you can of course pipe to that command ,
the var $visitor contain the string : ‘current number of users: 234’
But only the number (234) is usefull to you ,
your can do :
echo $visitor | sed -e "s/current number of users: //g"
the result is going to be : 234