CODEWITHSUNDEEP
regexgrep
Morad Semmar
Morad Semmar

Reputation: 1

3 condition AND in grep

I am trying to conduct a search of three conditions joined with AND with grep

I am able to search for b, AND ghkj like this:

grep -e "b,.*ghkj"

but I am unable to search for b, AND ghkj AND uuuuuu like this:

grep -e "b,.*ghkj.*uuuuuu"

How do I create a 3 condition AND search with grep?

Upvotes: 0

Views: 2280

Answers (1)

Will Barnwell
Will Barnwell

Reputation: 4089

There is no AND operator in grep (or any regex language afaik)

grep -E -e 'aaa.*bbb'

Matches any line that includes 'aaa' followed by any number of characters (.*) and then 'bbb', this simulates an AND in that it matches lines containing 'aaa' and 'bbb' in that order, but it will not match 'bbbaaa'. To get all lines containing 'aaa' and 'bbb' we can use an OR (|) to cover all possible cases.

grep -E -e 'aaa.*bbb|bbb.*aaa'

This strategy does not extend well to 3 or more clauses though, since the number of cases grows exponentially.

Instead we can use pipes to achieve an AND.

grep -E -e 'aaa' file | grep -E -e 'bbb' | grep -E -e 'ccc'
  1. The first grep finds all lines in file containing 'aaa' and outputs them.
  2. The second grep takes this output and finds all lines containing 'bbb' and outputs them.
  3. The third grep takes this output and finds all lines containing 'ccc' and outputs them.

The final output will only be lines from file which contain 'aaa' AND 'bbb' AND 'ccc' in any order.

Upvotes: 2

Related Questions