Makefile-tutorial/regex.sh

#!/bin/bash

#provide one word/sentence as an argument to the script.
#If in that sentence will be ip addresss, find out, if that
#ip address is reachable or not.

#argument check
if [ $# -ne 1 ]; then
    echo "Provide exactly one argument e.g. $0 argument"
    exit 1
fi

VAR1=$1
#ip address regex
REGEX="[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[[:digit:]]{1,3}"

#regex check
if ! [[ $VAR1 =~ $REGEX ]]; then
    echo "No IP address provided"
    exit 2
fi

IP=${BASH_REMATCH[0]}

#find if ip address is reachable or not
ping -c4 $IP 1>/dev/null

#1>/dev/null
#It will redirect standard output and prevent
#any output to print on screen.

if [ $? -eq 0 ]; then
    STATUS="ALIVE"
else
    STATUS="DEAD"
fi

echo "IP found: $IP ($STATUS)"