CODEWITHSUNDEEP
shellsed
4everLRG
4everLRG

Reputation: 35

Extract IP address from /etc/hosts file with SED command

I would like to extract the IP v4 address only from my /etc/hosts file with shell sed command.

I managed to isolate those line with localhost at the end of the line with the following command:

$ sed  -E '/localhost$/!d ' host_1 | sed -n 1p

which gave me the following output :

# 127.0.0.1 localhost

How can I only extract the IP v4 address alone form the above result?

Upvotes: 1

Views: 1890

Answers (4)

user20432570
user20432570

Reputation:

Late but you can try this :

sed  -E '/localhost$/!d ' host_1 | sed -n 1p | sed -r 's/\localhost//g'

The last part replaces the grep used by 4everLRG

If you need to extract localhost IP from /etc/hosts make sure to replace host_1 with /etc/hosts

Upvotes: 0

James Brown
James Brown

Reputation: 37394

The test data:

$ cat file
127.0.0.1 localhost
# 127.0.0.2 localhost
127 127.0.0.3 localhost

The sed:

$ sed -n  's/\(.*[^0-9]\|\)\([0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+\).*/\2/p' file

The output:

127.0.0.1
127.0.0.2
127.0.0.3

The sed with the -E switch:

$ sed -nE  's/(.*[^0-9]|)([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+).*/\2/p' file

Upvotes: 1

loa_in_
loa_in_

Reputation: 1011

sed  -E '/localhost$/!d '   /etc/hosts | awk '{print $1}' | grep -v :

Upvotes: 0

4everLRG
4everLRG

Reputation: 35

I tried this command and it works fine.

$ sed  -E '/localhost$/!d' host_1 | sed -n 1p  |grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b"

output: 127.0.0.1

Nonetheless I am still curious about how can I substitute the grep by a sed command.

Upvotes: 0

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