Use grep with or [duplicate]

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How do I grep for multiple patterns with pattern having a pipe character? (13 answers)

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How do I search in a textfile with grep for the occurrence of a word or another word?

I want to filter the apache log file for all lines including "bot" or "spider"

cat /var/log/apache2/access.log|grep -i spider

shows only the lines including "spider", but how do I add "bot"?

Answer 1

use classic regex:

grep -i 'spider\|bot'

or extended regex (or even perl regex -P):

grep -Ei 'spider|bot'

or multiple literal patterns (faster than a regular expression):

grep -Fi -e 'spider' -e 'bot'

• tripleee: +1 for covering multiple bases and also (implicitly) losing the cat.

Answer 2

cat /var/log/apache2/access.log | grep -E 'spider|bot'

With the -E option you activate extended regular expression, where you can use | for an logical OR.

Besides, instead of invoking another process - cat - you can do this with

grep -E 'spider|bot' /var/log/apache2/access.log

Answer 3

$ cat /var/log/apache2/access.log|grep -i 'spider\|bot'

The above will do the job.

You can also use egrep

$ cat /var/log/apache2/access.log|egrep -i 'spider|bot'

egrep is extended grep (grep -E). You will not have to use \ before | if you use egrep.

Answer 4

You can use egrep instead:

cat /var/log/apache2/access.log|egrep -i 'spider|bot'

• manatwork: "egrep is the same as grep -E. ... Direct invocation as ... egrep ... is deprecated" – man grep
• tripleee: -1 The double pipe || means 'or', it's not a pipe at all. Also you might want to fix the UUCA.
• Johan: The double-pipe ignored, on some platforms grep -E is not available and egrep is the only option.
• BitsOfNix: the double | was a mistype actually.