Bash script variable NULL instead of value of expression

bdrockwell · 11-17-2010, 12:27 AM

Quote:

#!/bin/sh

for i in {1..10}
do
for j in {1..50}
do
echo `host 129.74.$i.$j` | awk '{print $5}'

set domain = `host 129.74.$i.$j` | awk '{print $5}'

echo $domain
done
done

The first echo generates something like: abc.de.fgh
The second echo generates:

Any help would be highly appreciated.

Kenny_Strawn · 11-17-2010, 12:34 AM

You just define the variable without set, like so:

Code:

#!/bin/sh

for i in {1..10}
do
for j in {1..50}
do
echo `host 129.74.$i.$j` | awk '{print $5}'

domain = `host 129.74.$i.$j` | awk '{print $5}'

echo $domain
done
done

druuna · 11-17-2010, 01:41 AM

Hi,

@bdrockwell: If you want to fill a variable with the output of a command:

domain="`host 129.74.$i.$j | awk '{print $5}'`"

Or

domain=$(host 129.74.$i.$j | awk '{print $5}')

@Kenny_Strawn: Removing the set part is not enough to fix the problem.......

Hope this helps

colucix · 11-17-2010, 01:42 AM

In assigments you cannot have spaces around the equal sign:

Code:

domain=`host 129.74.$i.$j | awk '{print $5}'`

moreover the command substitution operator (backticks) must include the entire command line (included the pipe and the awk command).