Match valid IP by grep and regular expression

Question

Please advice what wrong in my syntax , and why the following regular expression doesn’t work

this example was tested under bash shell:

echo 12.212.12.198 | grep "^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]| [1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$"

Not get any output

The same about all IP’s as 192.9.200.12 , 172.18.12.34 , etc …

Jotne · Accepted Answer · 2014-07-20T16:41:13.560

1

You are missing -E (PATTERN is an extended regular expression (ERE))
Here is one good working found on google:

grep -E "^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$"

This as four part of ([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]) that work like this

[1-9]           # 1-9
[1-9][0-9]      # 10-99
1[0-9][0-9]     # 100-199
2[0-4][0-9]     # 200-249
25[0-5]         # 250-255

Leading 0 is not valid, so this does not give valid if there is leading 0

edited Jul 20 '14 at 16:41

answered Jul 20 '14 at 07:48

Jotne

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about your first example its also match not valid IP's as 2212.212.12.198 – maihabunash Jul 20 '14 at 08:13
@maihabunash You are correct, fixed. – Jotne Jul 20 '14 at 08:16
One point for a possible improvement: IPs with leading zeros are invalid. – Cyrus Jul 20 '14 at 09:52
@Cyrus You are correct. Updated my post – Jotne Jul 20 '14 at 16:34

Match valid IP by grep and regular expression

1 Answers1