Knowledge Base

Linux for the developer

These articles discuss Linux-related topics that can help as you develop or administer your web site.

Using the shebang

The shebang is a line in a script file that specifies which program should run the script. Using the correct shebang is especially important for CGI script files.

Managing the inode count

The inode count represents the total number of files and directories in an account or on a disk. This article shows you how to determine the inode count for your account.

Determining high disk usage locations

Learn how to determine where your account is using the most disk space.

Using screen

You can use the screen program to open multiple text windows within a single SSH session. If you frequently work from the command line, particularly over an unstable internet connection, screen is a valuable addition to your toolbox.

Monitoring resource usage

The top and atop commands enable you to monitor resource usage for your account in real-time from the command line. Learn how to use them here.

Using rsync

The rsync program allows you to easily synchronize directories between two locations. For example, one common use of rsync is to create a backup. Learn how to use rsync here.

Using cURL

You can use the cURL program to transfer files to your account from the command line. The cURL program is often a good substitute for the wget program.

Disabling e-mail notifications from cron jobs

By default, cron sends e-mail notifications when it runs a cron job. This article shows how to disable this behavior.

Using ImageMagick

ImageMagick is a powerful suite of programs that are used to manipulate image files. Learn more here.

Changing the time zone in the Linux shell

By default, A2 Hosting's servers use the US Eastern Standard Time (EST) time zone. This article shows how to configure your shell account to use a different time zone.

Cron jobs reset to 15-minute intervals

This article only applies to shared hosting and reseller accounts. For server performance and stability reasons, cron jobs with intervals less than 15 minutes are reset to 15-minute intervals automatically.

Installing and configuring Advanced Policy Firewall

You can use APF to help secure your VPS or dedicated server. Learn more here.

Configuring a firewall using iptables

The iptables program enables you to set up a firewall and help secure your server. Please note that this article only applies to unmanaged hosting packages.

Setting the default text editor in Linux

Learn how to set the default text editor for the Linux command-line environment.

Determining a server’s memory usage

Learn how to determine the correct amount of free and used memory on a server.

Working with file checksums

Learn how to generate checksums for your files and verify their integrity.

Installing the EPEL repository on CentOS

The Extra Packages for Enterprise Linux (EPEL) repository contains many additional useful packages for CentOS. Learn how to install this repository on your unmanaged server.

Running a cron job after a server reboot

You may want to run a script or application in a cron job automatically after a server reboots. This article shows you how.

Understanding system load averages

This article discusses how to view and interpret system load averages.

Conntrack sessions

Learn what conntrack sessions are, why they are important, and how to monitor them for your server.