LINUX: Using sed to delete lines from files

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One thing you may want to automate from your scripts or command line is to delete lines from files. We looked in an earlier video at using echo to append a line to a file to disable an upstart service; but if you want to enable the service you would need to delete the line. sed -i /^manual/d filename will work a treat for us in this case, lets to a quick look, just 2 minutes this video.