i wanted to edit the squid.conf file intending to add other bad sites to the file but after that squid failed to start.
Applications failing to start after a modification is made to a configuration file is a common occurrence, even for those who have been using Linux for many years and usually indicates an error in the configuration file. The error can be something as simple as a misspelling, incorrect punctuation, or even an unknown keyword caused by a version incompatibility. When this sort of thing happens, one of the first things you should do is check your log files, and with Centos, /var/log/messages would be a good place to start. More often than not, the log file will show you exactly what you did wrong, even pointing you to the line and word that is problematic.