For so many commands which i type are correct even then i have errors like unable to locate package or sometimes it gives "invalid operation" . This error really kills me, how can i fix this?
is missing a mandatory option. To install or remove use...
An more morecent alternative to
You should prefer
Everyone types commands incorrectly sometimes, that is life. Unless you are encountering a bug in the software (which is highly unlikely), the command is typed wrong. Look for typos, then for logical errors, and if all else fails try typing the command again.