Tag Archives: scripts

Executing a SQL query from a script in Linux

It was necessary recently to write a script that executes a sql query into the MySQL database.
Example content:

# Description, here I wrote for others that the script is added to the crontab, so that it is not moved
mysql -u USER -pPASSWORD -h 127.0.0.1 -e "UPDATE nika_system.abon SET otkl=0 WHERE depozit > '10' AND (otkl='-1' OR otkl='-2');";

In order for the script to run automatically, open the crontab file in any text editor (in the nano editor CTRL+X for the output and y/n for saving or canceling the changes):

sudo nano /etc/crontab

Add the following line to it:

0 9 * * * root /home/nika/scripts/reset_credit_nika.sh > /dev/null 2>&1

Now every day at 9 am the script will be executed.

Here is an example of daily automatic output of data from a sql table into a text file:

#!/bin/bash
mysql -u USER -pPASSWORD -h 192.168.1.1 -s -N -e "SELECT id FROM nika_system.abon WHERE tarif=109;";

In /etc/crontab we add:

0 8 * * * root /scripts/freektb.sh > /srv/samba/dir/mirazh/$(date +%Y-%m-%d).txt

For security reasons, it’s better not to specify the password in scripts, see my article – Connecting to MySQL from localhost without entering a password

Bash script to reboot network devices via telnet

I noticed that some cheap managed network equipment can start working incorrectly in a few days or weeks, so I had an idea to write a reboot script and add it to the cron.

Content of the script:

#!/bin/bash
(
sleep 5
echo "admin"
sleep 5
echo "password"
sleep 5
echo "reboot"
sleep 5
echo "y"
sleep 5
echo "quit"
) | telnet 192.168.1.10

sleep 5 means a pause of 5 seconds after each command, this value is optimal for long thinking equipment. For example, for client switches D-Link DES-3200 pause can be completely removed or set 1.

See also:
Using and configuring CRON