Cron job creates empty files - bash

Question

I want to preface that I am a newbie that picked up shell scripting 2 weeks ago.
Hey guys I need help with something, hope someone can point me in the right direction. I have a script that works when I run it from the command line but every time I run it with a crontab, the output is a few empty files. Does anyone know why?
That's the code down there
#!/bin/bash
#Provide an IP address as an argument to use nmap
#make sure to add the full range with (0-225 or 0/24) at the end
IPADDRESS=$(hostname -I | awk '{print $1}')
network-scan(){
if [ $1 ]
then
sudo nmap -sn $1
else
sudo nmap -sn 192.168.1.0-255
fi
}
#Scan the whole network and only prints the IP addresses minus your own
#Sends the IP addresses to a file
network-scan | grep -i 'Nmap scan report' | \
sed 's/\ /\n/g'|sed 's/(//g'|sed 's/)//g' | \
grep '[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*' | grep -v ${IPADDRESS} > ip_addresses
#Scan the whole network and only prints the MAC addresses
#Sends the MAC addresses to a file
network-scan | grep -i 'MAC Address:' | \
awk '{print $3}' > mac_addresses
#Put the IP and MAC addresses in the same file
paste ip_addresses mac_addresses | \
column -s $'\t' -t > "scan_$(date +%d-%m-%Y_%H:%M:%S)"
#Notify that a file with the IP and MAC addresses has been created on the Desktop
echo "A file containing the results of the scan has been created on the Desktop"
exit 0

Answer 1

You are using
network-scan | grep
without passing any parameter.
Hence network-scan function always using
sudo nmap -sn 192.168.1.0-255
when you run it from command line are you passing any parameter ?
echo $IPADDRESS inside the script when executing at cron and at command line for debugging.
network-scan | grep -i 'Nmap scan report' | \
sed 's/\ /\n/g'|sed 's/(//g'|sed 's/)//g' | \
grep '[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*' | grep -v ${IPADDRESS}
Since you are obtaining empty output, validate each command and append(test) each OR operators to know where it is removing required output.