CODEWITHSUNDEEP
stringlualua-patterns
vkp_stack
vkp_stack

Reputation: 157

Extracting an IP address from a particular string in Lua

I want to extract a particular value from a string . This is my string 

iptables -t nat -A PREROUTING -p tcp -m tcp --dport 666 -j DNAT --to-destination 192.168.19.55

How can i extract 192.168.19.55 ip address from this string using string.match in lua ?

I done with local ip = s:match("--to-destination (%d+.%d+.%d+.%d+)")) but i didn't get the value 192.168.19.55 . I am getting empty value .

Any mistake in this ? Any suggestions ?

Upvotes: 3

Views: 3500

Answers (2)

lhf
lhf

Reputation: 72312

This also works:

ip = s:match("destination%s+(%S+)")

It extracts the next word after destination, a word being a run of nonwhitespace characters.

Upvotes: 3

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626794

Use

local s = "iptables -t nat -A PREROUTING -p tcp -m tcp --dport 666 -j DNAT --to-destination 192.168.19.55"
ip = s:match("%-%-to%-destination (%d+%.%d+%.%d+%.%d+)")
print(ip)
-- 192.168.19.55

See the online Lua demo.

Note that - is a lazy quantifier in Lua patterns, and thus must be escaped. Also, a . matches any char, so you need to escape it, too, to match a literal dot.

See more at Lua patterns Web page.

Upvotes: 4

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