Bash Ping Site Check Script. (Longer Timeout) - linux

Question

I am currently using a Raspberry PI as a ping server and this is the script that I am using checking for a ok response.
I'm not familiar with bash scripting so it's a bit of a beginner question with the curl call, is there a way to increase the timeout, as it keeps reporting false down websites.
#!/bin/bash
SITESFILE=/sites.txt #list the sites you want to monitor in this file
EMAILS=" " #list of email addresses to receive alerts (comma separated)
while read site; do
if [ ! -z "${site}" ]; then
CURL=$(curl -s --head $site)
if echo $CURL | grep "200 OK" > /dev/null
then
echo "The HTTP server on ${site} is up!"
sleep 2
else
MESSAGE="This is an alert that your site ${site} has failed to respond 200 OK."
for EMAIL in $(echo $EMAILS | tr "," " "); do
SUBJECT="$site (http) Failed"
echo "$MESSAGE" | mail -s "$SUBJECT" $EMAIL
echo $SUBJECT
echo "Alert sent to $EMAIL"
done
fi
fi
done < $SITESFILE

Answer 1

Yes, man curl:
--connect-timeout <seconds>
Maximum time in seconds that you allow the connection to the server to take.
This only limits the connection phase, once curl has connected this option is
of no more use. See also the -m, --max-time option.
You can also consider using ping to test the connection before calling curl. Something with a ping -c2 will give you 2 pings to test the connection. Then just check the return from ping (i.e. [[ $? -eq 0 ]] means ping succeeded, then connect with curl)
Also you can use [ -n ${site} ] (site is set) instead of [ ! -z ${site} ] (site is not-unset). Additionally, you will generally want to use the [[ ]] test keywords instead of single [ ] for test constructs. For ultimate portability, just use test -n "${site}" (always double-quote when using test.

Answer 2

I think you need this option --max-time <seconds>
-m/--max-time <seconds>
Maximum time in seconds that you allow the whole operation to take. This is useful for preventing your batch jobs from hanging for hours
due to slow networks or links going down.
--connect-timeout <seconds>
Maximum time in seconds that you allow the connection to the server to take. This only limits the connection phase, once curl has connected this option is of no more use.