For the test, I sketched a Cisco Catalyst 6509-E automatic backup configuration script.
Actually the script itself:
#!/bin/bash
# Backup CISCO config
(
sleep 5
echo "user"
sleep 4
echo "password"
sleep 4
echo "copy running-config tftp:"
sleep 2
echo "192.168.1.4"
sleep 2
echo "cisco.cfg"
sleep 6
echo "exit"
) | telnet 192.168.1.5
mv /srv/tftp/cisco.cfg /backups/devices/cisco/`date +%Y-%m-%d`_cisco.cfg
find /backups/devices/cisco/ -type f -mtime +30 -exec rm {} \;
Add the contents of the script, for example, to the backup_cisco.sh file and add it to cron, adding the following line to the /etc/crontab file:
0 2 * * * root /backups/scripts/backup_cisco.sh > /dev/null 2>&1
The file can be opened for example in the text editor nano (Ctrl+X to exit, y/n to save or cancel changes):
sudo nano /etc/crontab
The script connects via telnet to 192.168.1.5 and copies the configuration to the tftp server 192.168.1.4, then the file is moved to a convenient directory for storage.
The last line in the script deletes files older than 30 days.
How to start the tftp server, see my articles: Installing and Configuring a TFTP Server in Ubuntu or Starting a TFTP server in Windows.
See also: Using and configuring CRON.