Monitor a log file and execute commands based on patterns

1. #!/bin/sh
2. tail -fn0 /var/log/file.log | while read line ; do
3.         echo “$line” | grep “pattern”
4.         if [ $? = 0 ]
5.         then
6.                 # Actions
7.                 echo “Yeah: $line”
8.         fi
9. done

Note