Linux study notes from 2012 to 2018. A personal journal.https://amargautam.co.uk/en-gbhttps://amargautam.co.uk/firewall-and-iptables/https://amargautam.co.uk/firewall-and-iptables/Opening ports 80, 110 and 143 by editing /etc/sysconfig/iptables, restarting the service and checking the rules, plus firewalld and ufw equivalents.Thu, 27 Dec 2018 00:00:00 GMThttps://amargautam.co.uk/how-to-install-magento-on-centoos-6/https://amargautam.co.uk/how-to-install-magento-on-centoos-6/My short checklist for installing Magento 1 on CentOS 6: download it, adjust Apache's httpd.conf and add the PHP mcrypt packages from EPEL.Sun, 16 Dec 2018 00:00:00 GMThttps://amargautam.co.uk/installation-of-apache-server/https://amargautam.co.uk/installation-of-apache-server/Installing Apache httpd with yum on CentOS or Red Hat, starting it at boot, enabling name-based virtual hosting on port 80 and testing the default page.Thu, 25 Oct 2018 00:00:00 GMThttps://amargautam.co.uk/installing-samba/https://amargautam.co.uk/installing-samba/The basic steps to install Samba with yum, edit its config files, add a Samba user, set folder ownership, test the config and restart the service.Mon, 04 Jun 2018 00:00:00 GMThttps://amargautam.co.uk/ssl-certificate-in-centos-webserver/https://amargautam.co.uk/ssl-certificate-in-centos-webserver/Creating a key, CSR and self-signed certificate with OpenSSL, adding them to Apache mod_ssl on CentOS, and redirecting HTTP to HTTPS.Mon, 07 May 2018 00:00:00 GMThttps://amargautam.co.uk/ossec-email-notification-configuration/https://amargautam.co.uk/ossec-email-notification-configuration/How to turn on OSSEC email notifications in ossec.conf, set the recipient, SMTP server and sender, choose the minimum alert level and restart OSSEC.Fri, 26 Jan 2018 00:00:00 GMThttps://amargautam.co.uk/to-check-log-services-activities-running-processess/https://amargautam.co.uk/to-check-log-services-activities-running-processess/Quick commands to see what a Linux server is doing: ps aux for processes, last for login history and netstat or ss for listening ports and services.Sun, 12 Mar 2017 00:00:00 GMThttps://amargautam.co.uk/how-to-make-crontab-job/https://amargautam.co.uk/how-to-make-crontab-job/The five crontab time fields and their allowed values, how to add jobs with crontab -e and list them with crontab -l, and worked schedule examples.Fri, 03 Mar 2017 00:00:00 GMThttps://amargautam.co.uk/basic-linux-commands/https://amargautam.co.uk/basic-linux-commands/My 2017 cheat sheet of everyday commands (mv, mkdir, less, rm, useradd, userdel), corrected, with how to read files in less and manage user accounts.Fri, 03 Mar 2017 00:00:00 GMThttps://amargautam.co.uk/rsync-over-ssh/https://amargautam.co.uk/rsync-over-ssh/Copying folders between servers with rsync over SSH, using a custom port and key, and how a trailing slash on the source changes where files end up.Thu, 08 Dec 2016 00:00:00 GMThttps://amargautam.co.uk/installation-of-zabbix-on-centos-6-3/https://amargautam.co.uk/installation-of-zabbix-on-centos-6-3/My steps for compiling Zabbix server and agent on CentOS 6.3, creating its MySQL database and copying the PHP web frontend into Apache.Thu, 08 Dec 2016 00:00:00 GMThttps://amargautam.co.uk/how-to-add-products-in-magento/https://amargautam.co.uk/how-to-add-products-in-magento/Where to add a new product in the Magento 1 admin, the main tabs to fill in, and why a new product might not appear on your shop.Wed, 11 May 2016 00:00:00 GMThttps://amargautam.co.uk/how-to-install-nagios-on-centos-6/https://amargautam.co.uk/how-to-install-nagios-on-centos-6/A short command list for building Nagios Core 3.4.4 and the Nagios plugins from source on CentOS 6, then logging in to the web interface.Mon, 25 Jan 2016 00:00:00 GMThttps://amargautam.co.uk/how-to-troubleshoot-apache/https://amargautam.co.uk/how-to-troubleshoot-apache/A checklist for when an Apache website will not load: DNS, service status, config syntax, error logs, listening ports, the firewall and SELinux.Sat, 23 Jan 2016 00:00:00 GMThttps://amargautam.co.uk/use-cron-to-sync-time-using-ntp/https://amargautam.co.uk/use-cron-to-sync-time-using-ntp/A daily cron job that syncs the clock with ntpdate, with each option explained, the missing server fixed, and today's chrony and timesyncd alternatives.Sun, 11 Oct 2015 00:00:00 GMThttps://amargautam.co.uk/how-to-install-nagios-in-linux-centos-server/https://amargautam.co.uk/how-to-install-nagios-in-linux-centos-server/A fuller Nagios Core source install on CentOS: nagios user and nagcmd group, web interface login, plugins, alert email address and a config check.Wed, 06 May 2015 00:00:00 GMThttps://amargautam.co.uk/how-to-install-centos5-8-netinstall/https://amargautam.co.uk/how-to-install-centos5-8-netinstall/Short steps for installing CentOS 5.8 from the netinstall image using the HTTP mirror settings. Historic: CentOS 5 reached end of life in 2017.Thu, 30 Apr 2015 00:00:00 GMThttps://amargautam.co.uk/common-linux-log-files/https://amargautam.co.uk/common-linux-log-files/A list of common files in /var/log and what they contain, with the Red Hat vs Debian/Ubuntu differences and how to read logs with journalctl today.Wed, 01 Apr 2015 00:00:00 GMThttps://amargautam.co.uk/how-to-install-and-configure-nfs-and-nfsv4-on-centos-6/https://amargautam.co.uk/how-to-install-and-configure-nfs-and-nfsv4-on-centos-6/Setting up an NFS server on CentOS 6, exporting a folder to a client, mounting it with NFS or NFSv4, keeping it after reboot and checking statistics.Sun, 16 Nov 2014 00:00:00 GMThttps://amargautam.co.uk/vi-editor-search-and-replace/https://amargautam.co.uk/vi-editor-search-and-replace/Reference for vi search and replace with :s, covering the current line, the whole file, line ranges, marks and the :g command, with confirm and case flags.Tue, 11 Nov 2014 00:00:00 GMThttps://amargautam.co.uk/how-to-install-openvpn-in-centos-6/https://amargautam.co.uk/how-to-install-openvpn-in-centos-6/My 2014 notes on installing OpenVPN on CentOS 6 with easy-rsa 2.0 certificates and PAM login, with corrections and notes on what to use today.Mon, 08 Sep 2014 00:00:00 GMThttps://amargautam.co.uk/basic-linux-administraiton-user-group-mgmt/https://amargautam.co.uk/basic-linux-administraiton-user-group-mgmt/Notes on creating users and groups, adding users to groups, reading and changing file permissions with chmod, and what /etc/shadow and /etc/group hold.Tue, 22 Jul 2014 00:00:00 GMThttps://amargautam.co.uk/change-update-mysqladmin-password/https://amargautam.co.uk/change-update-mysqladmin-password/Set or change the MySQL root password with mysqladmin, create a user and grant privileges, with corrected commands and MySQL 8.0 syntax.Mon, 24 Mar 2014 00:00:00 GMThttps://amargautam.co.uk/how-to-comment-all-lines-in-vi-editor/https://amargautam.co.uk/how-to-comment-all-lines-in-vi-editor/Comment out every line of a file in vi with one search-and-replace command, plus how to comment a range, undo it and use Vim visual block mode.Fri, 21 Feb 2014 00:00:00 GMThttps://amargautam.co.uk/amazon-aws-ssh-failed-permission-denied/https://amargautam.co.uk/amazon-aws-ssh-failed-permission-denied/Why SSH to an AWS EC2 Linux instance fails with Permission denied, and how to fix it with the right .pem file permissions and login user name.Fri, 07 Feb 2014 00:00:00 GMThttps://amargautam.co.uk/how-to-install-redmine-on-centos/https://amargautam.co.uk/how-to-install-redmine-on-centos/My notes from installing Redmine 1.4 on CentOS 6.3 with MySQL, Ruby gems, Passenger and an Apache virtual host, with corrected commands.Sun, 02 Feb 2014 00:00:00 GMThttps://amargautam.co.uk/basic-vi-editor/https://amargautam.co.uk/basic-vi-editor/The first vi editor commands a beginner needs: open a file, switch to insert mode, type text, then save or quit, with the original save command corrected.Wed, 07 Aug 2013 00:00:00 GMThttps://amargautam.co.uk/replication-of-mysql-server/https://amargautam.co.uk/replication-of-mysql-server/Step-by-step notes for MySQL replication between two servers: my.cnf settings, a replication user, a locked dump, and CHANGE MASTER TO.Sun, 21 Jul 2013 00:00:00 GMThttps://amargautam.co.uk/command-differents-windows-linux-centos/https://amargautam.co.uk/command-differents-windows-linux-centos/A table of everyday MS-DOS/Windows Command Prompt commands and their Linux equivalents, such as copy and cp, dir and ls, del and rm, with examples.Thu, 23 May 2013 00:00:00 GMThttps://amargautam.co.uk/how-to-remove-shipping-and-tax-block-from-checkout-page-magento/https://amargautam.co.uk/how-to-remove-shipping-and-tax-block-from-checkout-page-magento/A short note pointing to a video on removing the shipping and tax block from the Magento 1 checkout page, plus what to check first.Wed, 17 Apr 2013 00:00:00 GMThttps://amargautam.co.uk/how-to-remove-index-php-in-magento/https://amargautam.co.uk/how-to-remove-index-php-in-magento/Turn on web server rewrites, set RewriteBase in .htaccess and clear the cache so Magento 1 URLs no longer contain index.php.Tue, 20 Nov 2012 00:00:00 GMThttps://amargautam.co.uk/basic-linux-commands-2/https://amargautam.co.uk/basic-linux-commands-2/Early notes on moving, renaming, viewing and deleting files with mv, mkdir, less and rm, plus adding and removing users, with fixes and examples.Sun, 28 Oct 2012 00:00:00 GMThttps://amargautam.co.uk/installation-and-configuration-iredmail-for-postfix-and-mail-server/https://amargautam.co.uk/installation-and-configuration-iredmail-for-postfix-and-mail-server/My short notes on downloading iRedMail 0.8.3 and running its installer script to set up a Postfix mail server, plus what to prepare and check.Wed, 05 Sep 2012 00:00:00 GMThttps://amargautam.co.uk/installation-of-centos-5-8/https://amargautam.co.uk/installation-of-centos-5-8/The CentOS 5.8 netinstall ISO downloads and the mirror site and directory settings for i386 and x86_64. Historic: CentOS 5 reached end of life in 2017.Wed, 08 Aug 2012 00:00:00 GMThttps://amargautam.co.uk/passwordless-ssh-login/https://amargautam.co.uk/passwordless-ssh-login/Setting up SSH key login so you can connect without typing a password, with the file permissions SSH needs and the safer ssh-copy-id method.Sat, 21 Jul 2012 00:00:00 GMThttps://amargautam.co.uk/file-partition-mount-fdisk/https://amargautam.co.uk/file-partition-mount-fdisk/How I partition a new disk with fdisk, format it as ext4 and mount it via /etc/fstab, with corrected steps, UUIDs and a warning on picking the right disk.Mon, 07 May 2012 00:00:00 GMT