Uly.me

cloud engineer

Create A Swap File

How to create a swap file.

A 2GB swap file.

dd if=/dev/zero of=/swapfile bs=1k count=2048k

Activate.

mkswap /swapfile
chmod 0600 /swapfile
systemctl daemon-reload
swapon /swapfile

To make swap permanent, add to /etc/fstab.

/swapfile  swap   swap    defaults   0 0

Check if swap is working.

cat /proc/swaps
free -h

CloudFormation Userdata

Here’s another way to add startup scripts to your instance during creation.

      UserData:
        Fn::Base64: !Sub |
          #cloud-config
          repo_upgrade: none
 
          runcmd:
            # Cloud init startup script
            - "bash /root/setup.sh"
 
          write_files:
            # Cloud init startup script
            - owner: root:root
              permissions: '0644'
              path: /root/setup.sh
              content: |
                #! /bin/bash -x
          write_files:
            # Cloud init startup script
            - owner: root:root
              permissions: '0644'
              path: /root/setup.sh
              content: |
                #! /bin/bash -x
                # run your bash commands here
                date > log.txt
                uptime >>  log.txt

The above script creates a file setup.sh and executes it during instance creation. The output is dumped to log.txt file.

Audacity Copy

I was getting an error when launching Audacity.

The error was:

“The system has detected that another copy of Audacity is running.”

However, Audacity wasn’t running at all. Not one process. It turned out to be just a locked file located in /var/tmp/audacity-[your-username].

All you have to do is delete the entire directory and rerun Audacity.

rm -rf /var/tmp/audacity=[your-username]/

Once deleted, Audacity starts right up with no issues.