Tinydns data file change ip with bash

Question

I am using tinydns and need to dynamicly change some ip in data file. I want to use bash script for it.

For example data file:

+sub1.example.org:282.196.222.245:14400
+sub2.example.org:278.179.280.253:14400
+sub3.example.org:285.117.214.234:14400

bash script has two variables:

old="282.196.222.245"
new="127.0.0.1"

I expect this result:

+sub1.example.org:127.0.0.1:14400
+sub2.example.org:278.179.280.253:14400
+sub3.example.org:285.117.214.234:14400

What is the best way to replace old ip to new (using awk, sed or smth else)?

score 1 · Accepted Answer · edited Jan 28 '14 at 17:09

1

You can use sed:

sed -i "s/$old/$new/g" filename

Here you have simple test:

# echo "+sub1.example.org:282.196.222.245:14400" >> filename

# cat filename
+sub1.example.org:282.196.222.245:14400

# old=282.196.222.245
# new=127.0.0.1

# sed -i "s/$old/$new/g" filename

# cat filename
+sub1.example.org:127.0.0.1:14400<br>

edited Jan 28 '14 at 17:09

fedorqui

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answered Jan 28 '14 at 13:18

dave

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"g" is not needed normaly but is absolutely not an issue – NeronLeVelu Jan 28 '14 at 13:31
You're right, it's my habit just like '>>' instead of '>' - I use it too often ;) – dave Jan 28 '14 at 13:34

score 0 · Answer 2 · answered Jan 29 '14 at 02:02

0

awk -v "old=$old" -v "new=$new" '$2 == old {$2 = new} {print}' filename > tempfile && mv tempfile filename

or

awk -v "old=$old" -v "new=$new" '$2 == old {$2 = new}1' filename > tempfile && mv tempfile filename

answered Jan 29 '14 at 02:02

Dennis Williamson

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score 0 · Answer 3 · answered Sep 02 '14 at 22:35

I think it's cleaner to avoid trying to monkey-patch data; instead, generate your data from several files, one of which only contains the dynamic record(s).

Then, from bash, you can just echo "+sub3.example.org:285.117.214.234:14400" >data.dynamic; make or similar.

Example Makefile:

data.cdb : data 
    tinydns-data

data : data.static data.dynamic
    cat data.static data.dynamic >data

Tinydns data file change ip with bash

3 Answers3