[SOLVED] grep- using regex to print all lines that do not contain a pattern (without -v)

Issue

How can I use regex, with grep, to print all lines that do not contain a pattern. I cannot use -v because I want to implement the regex within a much more complicated one, for which -v would be impractical.

But whenever I try to print lines that do not contain a pattern, I do not get the expected output.

For example, if I have this file:

blah blah blah
hello world
hello people
something

And I want to print all lines that do not contain hello, the output should be:

blah blah blah
something

I tried something like this, but it won't work:

egrep '[^hello]' file

All answers on SO use -v, I can't find one using regex

Solution

You cannot use "whole" words inside of a character class. Your regular expression currently matches any character except: h, e, l, o. You could use grep with the following option and implement Negative Lookahead ...

grep -P '^(?!.*hello).*$' file

• -P option interprets the pattern as a Perl regular expression.

Ideone Demo

Answered By - hwnd

Answer Checked By - Mildred Charles (WPSolving Admin)