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Monthly Archives / October 2016

  • Oct 28 / 2016
  • 0
Linux

Add a confirmation dialog with bash

If you have a bash script doing some critical actions, it can be useful to add a confirmation dialog to double check with the user that he really wants to perform the action.

Here is a very simple script allowing this kind of checking:

#!/bin/bash
echo "Welcome to your favourite script!"
read -r -p "Are you sure you want to execute it? [y/N] " response
if [[ $response =~ ^([yY][eE][sS]|[yY])$ ]]
then
  echo "Execution in progress..."
  # Write your action here
else
  echo "Action canceled."
  exit
fi
echo "End of script."

Output will look like:

  • Case ‘yes’:
    $ bash script_yesno.sh 
    Welcome to your favourite script!
    Are you sure you want to execute it? [y/N] y
    Execution in progress...
    End of script.
    
  • Case ‘no’:
    $ bash script_yesno.sh 
    Welcome to your favourite script!
    Are you sure you want to execute it? [y/N] N
    Action canceled.
    

It’s up to you customizing it depending on your needs and your feelings!

  • Oct 19 / 2016
  • 0
Linux

Apache Tomcat – Get logs directly cleaned with rotation

Tomcat allows you to rotate easily your log files with AccessLogValve but it can be more difficult to get cleaning in logs directories automatically.

For that, you can easily use some smart find commands combined with actions:

  1. Get logs older than 3 days compressed so they can be smaller but still accessible
    find /var/log/tomcat/ -mtime +3 -regex ".*\.\(log\|txt\)$" -exec gzip "{}" \;
  2. Get logs older than 60 days deleted permanently
    find /var/log/tomcat/ -mtime +60 -name "*.gz" -exec rm "{}" \;

You will probably have to adjust the logs path depending on your needs, and you can also modify the retention time for each action.
Once the command looks correct with what you’re expecting, you can set them up as cron so it can be executed automatically every day.

  • Oct 14 / 2016
  • 0
Linux

Generate a random file with specific size

It’s possible to easily generate a random file with specific size filled differently depending on the needs:

  • Fill a 200MB file with zeroes
    dd if=/dev/zero of=/tmp/file.out bs=1024KB count=200
    
  • Fill a 200MB file with random values (longer than zeroes – depending on processor)
    dd if=/dev/random of=/tmp/file2.out bs=1024KB count=200

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