how to change dhcp-range using shell scirpt via Variable

Question

Dear All,

I have small query for Linux Shell Scripting , below is my requirement:

I have configured dnsmasq.conf , and it is working fine , I want to create script which automatically change the configuration of sever based on small input from user:

dhcp-range=192.168.4.200,192.168.4.230,2h

From this line I want to change start range and end range by script,This IP will not be fix all the time so I can not use "192.168.4.200" in my script with sed , I want to put 192.168.4.200 (or any IP there on dhcp-range line with variable $startip) and 192.168.4.230 with (variable $endip)

I tried using grep -o '[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}' and also tried with awk but till now no success.

Answer 1

Something like this what you're thinking?

[felsburr@agnus ~]$ cat /tmp/dnsmasq.conf
dhcp-range=192.168.4.200,192.168.4.230,2h

[felsburr@agnus tmp]$ ./dnsMasqUpdate 192.168.0.1 192.168.0.100

[felsburr@agnus tmp]$ cat dnsmasq.conf
dhcp-range=192.168.0.1,192.168.0.100,2h


[felsburr@agnus tmp]$ cat ./dnsMasqUpdate
#!/bin/bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin
_sed=/bin/sed

dnsConfFile=/tmp/dnsmasq.conf

startip=${1}
endip=${2}

$_sed -i "s/^dhcp-range=.*/dhcp-range=${startip},${endip},2h/" ${dnsConfFile}

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how to change dhcp-range using shell scirpt via Variable

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