How do I get sed to use a user input variable?

Question

It doesn't seem like sed is aware of the $IP variable. How can I get the following to work?

read -p "Please enter the line number with the IP you wish to block from accessing the Internet? " IP

echo $IP

IP_LINE_NUMBER=`nmap -n -sn 192.168.3.0/24 -oG - | awk '/Up$/{print $2}' | sed  '$IPq;d'`

echo $IP_LINE_NUMBER

Possible duplicate of [Replace a string in shell script using a variable](https://stackoverflow.com/questions/3306007/replace-a-string-in-shell-script-using-a-variable) — Benjamin W., Jun 10 '17 at 04:25

codeforester · Accepted Answer · 2017-06-10T01:29:30.700

0

You have to use double quotes and put {} around IP:

ip_line_number=$(nmap -n -sn 192.168.3.0/24 -oG - | awk '/Up$/{print $2}' | sed  "${IP}q;d")

Note: you need command substitution $(...) to get the output into your variable

See also:

edited Jun 10 '17 at 01:29

answered Jun 10 '17 at 01:26

codeforester

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Corrected - needed a `{}` around the variable. Please try. – codeforester Jun 10 '17 at 01:30
I'm sorry, bud but it yields this error: sed: -e expression #1, char 3: `}' doesn't want any addresses – user8022637 Jun 10 '17 at 01:34
I apologize. You were right. THANKS! It works. Have a great day! – user8022637 Jun 10 '17 at 01:36

How do I get sed to use a user input variable?

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