mjhjmtu

I'm trying to write a script to run a command and if the output of the command is 3 then script should exit and if it's not 3 then the script should send an email to let me know the count is not 3.
I wrote this code below but for some reason every time I run it, i keep getting email saying the output is not 3 even though it's 3.

#!/bin/bash

Server_Count=""
 nslookup servers | grep -i "Address: 10" | wc -l > /dev/null
 if [ $? == 3 ]; then
 Server_Count="$?"
else
 echo "Server Count is not 3 .. Please check" | mail -s "Server count issue" Katkota@katkota.com

fi

$? will be the exit code of the previous command not the result of the previous command. So assuming the command is successful, $? will be 0.

You want command substitution:

#!/bin/bash

server_count=$(nslookup servers | grep -i "Address: 10" | wc -l)
if [[ "$server_count" -ne 3 ]]; then
 echo "Server Count is not 3 .. Please check" | mail -s "Server count issue" Katkota@katkota.com
fi

This will set server_count to the results of wc -l so there is no need to set it again in your if statement. Therefore I have negated the if check (if server count does not equal 3 send the email, otherwise do nothing).

Also the -ne check is being used here which is the correct check for integer comparison.

On a side note you were using the POSIX shell test [ ... ] with a bash comparison operator ==. This will still work on many systems but beware when using [ ... ] you should use = and when using [[ ... ]] you can use either = or ==.

As Jesse_b explained, your code does not work since you are looking at the return status of wc -l rather than the data returned from it.

if nslookup servers | grep -c -iF "Address: 10" | ! grep -q -xF 3; then
 echo 'Server count is not 3... please check' | mail -s 'Server count issue' Katkota@katkota.com
fi

This gets rid of having to save things into variables by counting the number of lines that matches the given string in the output of nslookup, and if that count is not exactly three, it will send an email.

With -c, grep will output the number of lines that matches the given pattern. The -q option to grep stops grep from generating output. Here, we're only interested in whether grep matches the 3 or not, and we check this by its return status. With -x we force a match across a whole line (i.e. we will match only 3 and not 30). The -F option makes grep do a string match instead of a regular expression match.