Chad's Blog

Tag: linux

  • automysqlbackup: line 551: mysqlshow: command not found

    I have been receiving the following error messages when backing up my MariaDB database every day: “/usr/local/bin/automysqlbackup: line 551: mysqlshow: command not found.” This probably happened when I switched from MySQL to MariaDB for my database. The automysqlbackup program has been reliable over the years in making nightly backups of my database. This is a popular piece of software used by many, and I highly recommend it. It can be downloaded at https://sourceforge.net/projects/automysqlbackup/. It is no longer actively maintained, yet it still works great. The last update was 2019-0720.

    I finally became tired of the daily email warning of the missing “mysqlshow” command and decided to take action. After investigation, I discovered that MariaDB uses the “mariadb-show” command instead of “mysqlshow”. Backups were being made correctly, but I wanted the error message to go away. The fix was simply opening up automysqlbackup from a command line text editor (nano) and searching (Ctrl + f in nano) for “mysqlshow” and replacing it with the “mariadb-show” command. The following lines contained “mysqlshow” to be replaced: 532, 538, 541, 544, 551, 555, 559. Nano also has a find/replace command to make this faster. I saved the file with a new name, “automysqlbackup-mariadb”, and updated the crondaily with the new script name. I am attaching the new script here for inspection and use.

    automysqlbackup-mariadbDownload

    mariadb-show reference: https://mariadb.com/docs/server/clients-and-utilities/administrative-tools/mariadb-show

    From the MariaDB website 2025-1130

    MariaDB Community Server is one of the most popular database servers in the world. The MariaDB database has been downloaded over 1 billion times and is the default over MySQL in the majority of Linux distributions. Created by MySQL’s original developers, MariaDB is compatible with MySQL and Oracle, and is guaranteed to always be open source.

    Thank you MariaDB for making a great opensource product!

  • Mthtv-backend fails after upgrade in Debian Bullyseye

    My mythtv settings are not saved or being read after upgrading mythtv-common. My mythtv server is Linux server 5.3.0-3-amd64 #1 SMP Debian 5.3.15-1 (2019-12-07) x86_64 GNU/Linux. All commands are done through the terminal. Last update is 2020-0106.

    view the version of Debian

    lsb_release -a

    No LSB modules are available.
    Distributor ID: Debian
    Description: Debian GNU/Linux bullseye/sid
    Release: testing
    Codename: bullseye

    I am having to reconfigure mythtv-common and mythtv-backend after every upgrade. The steps to reconfigure the packages are listed below.

    Reconfiguring mythtv-common

    # dpkg-reconfigure --force mythtv-common

    Reconfiguring mythtv-database

    # dpkg-reconfigure --force mythtv-database

    restart the mythtv-backend and check that it is running

    # systemctl restart mythtv-backend

    # systemctl status mythtv-backend

    The following line shows success.

    Active: active (running) since Mon 2020-01-06 21:15:15 CST; 2s ago

  • Anbox on Debian 11 Bullseye

    Installation

    Installation instructions from https://docs.anbox.io/userguide/install.html.

    Install snap on computer. I already had it installed.

    Kernel modules have to be installed. https://docs.anbox.io/userguide/install_kernel_modules.html and https://github.com/Anbox/Anbox-modules

    I followed the the github website for installing kernel modules.

    Install the anbox snap or use the debian package. I used the debian package.

    apt install anbox

    Install Applications

    https://docs.anbox.io/userguide/install_apps.html

    Android applications for downloading https://www.apkmirror.com/uploads/

    Android on qemu

    I would like to try this. QEMU has been around longer and hopefully more stable. https://fosspost.org/tutorials/install-android-8-1-oreo-on-linux

    Last updated on 2020-0102

  • Installing Handbrake 1:1.2.2-dmo6 in Debian 11 Bullseye (testing)

    The handbrake website is https://handbrake.fr/. I installed from the command line.

    sudo apt-get install handbrake handbrake-gtk

    Handbrake can be started from the command line with the following command:

    gbh

    End 2019-1106

  • Renewing a Certbot Letsencrypt Webserver Certificate

    Situation: 2019-0417: I run my own webserver and my SSL/TLS encryption certificates expired.

    Background: I like to use certbot to create and manage my SSL/TLS certificates and the certificates expire every 90 days. Certbot is an easy-to-use automatic client that fetches and deploys SSL/TLS certificates for your web server. https://certbot.eff.org/about/

    My server is running:
    Linux server 4.17.0-1-amd64 #1 SMP Debian 4.17.8-1 (2018-07-20) x86_64 GNU/Linux
    Distributor ID: Debian
    Description:    Debian GNU/Linux testing (buster)
    Release:        testing
    Codename:       buster

    Assessment: I will outline the steps I took for renewing my certificate.

    Implementation: All commands are run in a terminal.

    1. stop the apache web server 

    systemctl stop apache2

    2. View the certificates installed and see their expiration date

    certbot certificates

    3. certbot command to renew certificate

    certbot certonly --cert-name [name-of-your-certificate-here] --force-renewal

    You get the following output

    How would you like to authenticate with the ACME CA?
     - - - - - - - - - - - - - - - - - - - - - - - - - - - 
    1: Apache Web Server plugin (apache)
    2: Spin up a temporary webserver (standalone)
    3: Place files in webroot directory (webroot)

    my selection:

    choose option 2 "Spin up a temporary webserver (standalone)"

    3. restart apache2 

     systemctl start apache2

    4. View certificate and check new date 

     certbot certificates

    5. Check certificate at ssl labs

    https://www.ssllabs.com/ssltest

    Finished 2019-0417

  • Linux Evolution Email broken/fails with Dovecot upgrade to Version 2.3

    2019-0320. My Evolution email client stopped stopped working after my server upgraded Dovecot was from version 2.2 to 2.3. I was getting TLS errors in Evolution. The error was “The reported error was “Failed to get capabilities: Error performing TLS handshake: An unexpected TLS packet was received.” I also have Roundcube webmail based email and it continued to work. The fix to the problem was not hard (Thank you Linux Community) however there is not much information on the internet now on solving this problem and thus the reason I felt motivated to write this post and give back to the Linux community.

    My server is Debian Sid (Buster/Debian 10). My email is setup using the guide from https://workaround.org/ispmail/stretch.

    The solution to the problem is change the ssl configuration in the dovecot file “/etc/dovecot/conf.d/10-ssl.conf”. I also increased the security of the SSL/TLS protocols used. References are: https://wiki2.dovecot.org/Upgrading/2.3 and https://wiki2.dovecot.org/SSL/DovecotConfiguration.

    I first needed to create a new Diffie Hellman parameters file that is involved in the TLS key exchange. This file collects entropy from the computer and took roughly an hour on my slow server computer. Enter these commands in the terminal. https://wiki2.dovecot.org/SSL/DovecotConfiguration#SSL_security_settings

    cd /etc/dovecot
    openssl dhparam 4096 > dh.pem

    I removed the following lines in file “/etc/dovecot/conf.d/10-ssl.conf”.

    ssl_protocols = !SSLv2 !SSLv3

    I added and modified the following lines in file “/etc/dovecot/conf.d/10-ssl.conf”.

    ssl_dh =</etc/dovecot/dh.pem
    ssl_min_protocol = TLSv1.2
    ssl_cipher_list = ALL:!DH:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH
    ssl_prefer_server_ciphers = yes

    Restart the dovecot service

    sudo systemctl restart dovecot

    Check that the dovecot service is running

    sudo systemctl status dovecot

    All done and Evolution email is working.

  • Nextcloud 14.04 broken with upgrade to php7.3 in Debian testing/sid

    Nextcloud 14.04 stopped working on me. I was getting a blank page on my nextcloud website. I found the following error message in my nextcloud logfile: 

    "Error: Call to undefined function OC\\App\\simplexml_load_file() at \/var\/www\/cc.com\/nextcloud\/lib\/private\/App\/InfoParser.php#64".

    It appears the problem was when php was updated from 7.2 to 7.3 however the apache2 webserver was trying to use the older php7.2 module and php7.3 module was not enabled. The solution is to disable the php7.2 and enable php7.3 module for apache2. The following commands are entered into the terminal.

    Disable the apache2 module php7.2

    sudo a2dismod php7.2

    Enable the apache2 module php7.3

    sudo a2enmod php7.3

    Restart the Apache webserver and show it’s running status

    sudo systemctl restart apache2 & sudo systemctl status apache2

    I found the following site helpful: https://tecadmin.net/switch-between-multiple-php-version-on-debian/

    The server was Debian testing/sid. 2019-0110


  • Certbot and Let’s Encrypt errors on creating a certificate

    I was having failures creating new certificates in certbot due to a change in their code. I previously ran the following command to create a website certificate for an apache server running on Debian 8 Jessie.

    # certbot run --verbose --text --apache --rsa-key-size 4096 --email your-email.com --agree-tos -d your-domain-name.com,alternative-domain-name.org,third-domain-name.com

    This used to work but now (2018-0226) it doesn’t. Here is the output of error:

    Performing the following challenges: 
Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA.
Exiting abnormally:
Traceback (most recent call last):
 File "/usr/bin/certbot", line 11, in <module>
 load_entry_point('certbot==0.10.2', 'console_scripts', 'certbot')()

    I found the answer here: https://github.com/certbot/certbot/issues/5405

    The following command worked, substitute working values for “your-email.com” and “your-domain-name.com”.

    # certbot certonly --standalone --verbose --text --rsa-key-size 4096 --email your-email.com --agree-tos -d your-domain-name.com --pre-hook "systemctl stop apache2" --post-hook "systemctl start apache2"

    This is for the following version of certbot.

    # certbot --version
certbot 0.10.2

    The end 🙂

  • Add SSL Certificate to Postfix and Dovecot with Let’s Encrypt

    I am running a Debian 8 Jessie email server with postfix and dovecot. I wanted to change from self signed certificates to certificates from Let’s Encrypt. It was easy to do and I wish had not waited so long to change. This blog post, https://www.shivering-isles.com/lets-encrypt-free-trusted-certificates-for-postfix-and-dovecot/ explained it perfectly for me, so there is no need for me to document the commands.

    https://letsencrypt.org/

  • Rotate your Rsync Backups with rotate-backups, similar to Time Machine

    I use rsync on gnome-ubuntu 15.10 to back up my data to my server running Debian 8. This creates incremental backups similar to Apples Time Machine. The backup runs every 2 hours so this creates more backups than needed at the expense of hard drive space. I used to manually delete the files from the server and would try to save a monthly backup, 8 weekly backups, 30 daily backups, and 2 weeks of every 2 hour backups. This was a time consuming process of manually selecting the files and thus I was not consistent about removing the extra backups. My backup scripts are written in python and I was going to write a script that would delete old backups that were not needed any more. Even better than writing your own script is finding one that has already been written such as https://rotate-backups.readthedocs.org/en/latest/#rotate-backups-simple-command-line-interface-for-backup-rotation. This script will automatically delete your old backups and you can configure it for many backups you want to keep.

    This script is well documented and easy to use. I give it my highest recommendation.