How to delete from a text file, all lines that contain a specific string?

Question

How would I use sed to delete all lines in a text file that contain a specific string?

Answer 1

You may consider using ex (which is a standard Unix command-based editor):

ex +g/match/d -cwq file

where:

• + executes given Ex command (man ex), same as -c which executes wq (write and quit)
• g/match/d - Ex command to delete lines with given match, see: Power of g

The above example is a POSIX-compliant method for in-place editing a file as per this post at Unix.SE and POSIX specifications for ex.

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The difference with sed is that:

sed is a Stream EDitor, not a file editor.^BashFAQ

Unless you enjoy unportable code, I/O overhead and some other bad side effects. So basically some parameters (such as in-place/-i) are non-standard FreeBSD extensions and may not be available on other operating systems.