BASH Help

[njiska]

Hey, it's been about 8 years since I last wrote a BASH script and I could use some quick help. Specifically I've forgotten how to write proper if comparison statements for program output. Essentially this is psuedocode of what I need:

Code: Select all

if <output of 'networksetup -getdnsservers Wi-Fi'> = '208.122.23.22\n 208.122.23.23'
   networksetup -setdnsservers Wi-Fi empty
else
   networksetup -setdnsservers Wi-Fi 208.122.23.22 208.122.23.23

I can't for the life of me remember how to correctly script that comparison in bash. It should be a stupid simple line so any help that can be offered is greatly appreciated.

I'm trying to quickly toggle between automatic and two set DNS servers in OS X and it seems to me a script is the easiest way.

[Barrakketh]

-eq

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[ `networksetup -getdnsservers Wi-Fi` -eq "208.122.23.22\n 208.122.23.23" ]

Or something along those lines. See this (the whole ABS guide is great).

[njiska]

Cool. That line is pretty much what I thought it was going to be. I'll take a look at the guide a little later.

[njiska]

Code: Select all

#!/bin/sh
DNS="208.122.23.22
208.122.23.23"
CURRENT=`networksetup -getdnsservers Wi-Fi` 

if [ "$CURRENT" -eq "$DNS" ]; then
   networksetup -setdnsservers Wi-Fi empty;
else
   networksetup -setdnsservers Wi-Fi 208.122.23.22 208.122.23.23;
fi

Returns:

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./testscript.sh: line 10: [: 208.122.23.22
208.122.23.23: integer expression expected

Any thoughts on why I've ended up with this error? I added a few Echos to the script to confirm the variables were being filled

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echo $DNS
echo "---"
echo $CURRENT 

and it printed

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208.122.23.22 208.122.23.23
---
208.122.23.22 208.122.23.23

[Barrakketh]

Any thoughts on why I've ended up with this error?

Use "=" instead of "-eq", and make sure there is whitespace around the "=".

I forgot that bash uses a different operator when you're comparing strings.

[njiska]

Brilliant. Script works. Thanks.