PHP script to execute a bash script - php

Question

I have 3 scripts (I have removed the help_page function from the networkstats.sh script when I pasted here to save some space):
api3.php
<?php
output = shell_exec('/bin/bash /usr/share/nginx/status/getnetworkstatsin.sh');
echo $output;
?>
getnetworkstatsin.sh
#!/bin/bash
ssh -i /tmp/id_rsa1 root#centos7clone bash -s -- -I < ./networkstats.sh
networkstats.sh
#!/bin/bash
interface=enp0s3
read -r inbytesold outbytesold < <(awk -v dev="^$interface:" '$1 ~ dev {
sub(/[^:]*:/,""); print $1, $9; exit }' /proc/net/dev)
sleep 1
read -r inbytesnew outbytesnew < <(awk -v dev="^$interface:" '$1 ~ dev {
sub(/[^:]*:/,""); print $1, $9; exit }' /proc/net/dev)
kilobitsin=$(( ( ( inbytesnew - inbytesold ) * 8 ) / 1024 ))
kilobitsout=$(( ( ( outbytesnew - outbytesold ) * 8 ) / 1024 ))
show_outgoing() {
echo $kilobitsout
}
show_all() {
echo "kilobits in: $kilobitsin"
echo "kilobits out: $kilobitsout"
}
if [[ $# -eq 0 ]];
then
help_page
exit 1
fi
for arg in "$#"
do
case $arg in
-h|--help)
help_page
;;
-I)
show_incoming
;;
-O)
show_outgoing
;;
-A|--all)
show_all
;;
esac
done
The problem I have is that when I execute the api3.php script from console, it is able to execute and return a value.
However when I try and execute from a webpage it fails to return anything.
I believe it is not even executing when I load it via the webpage by navigating to localhost/api3.php. Can someone help, what is the reason behind this? I have added
nginx ALL=NOPASSWD: /usr/share/nginx/status/getnetworkstatsin.sh
To my visudo section, I have tried to change permissions of all files involved to 777 (temporally) without success.
EDIT: I should also mention that all these scripts are located inside /usr/share/nginx/status which nginx has access to.