When I drafted this article, I really came-up with 7 sysadmin habits. But, out of those 7 habits, three really stood out for me.

While habits are good, sometimes rules might even be better, especially in the sysadmin world, when handling a production environment.

Rule #1: Backup Everything ( and validate the backup regularly )

Experienced sysadmin knows that production system will crash someday, no matter how proactive we are. The best way to be prepared for that situation is to have a valid backup.
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In bash shell, when you use a dollar sign followed by a variable name, shell expands the variable with its value. This feature of shell is called parameter expansion.

But parameter expansion has numerous other forms which allow you to expand a parameter and modify the value or substitute other values in the expansion process. In this article, let us review how to use the parameter expansion concept for string manipulation operations.

This article is part of the on-going bash tutorial series. Refer to our earlier article on bash { } expansion.
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Question: While downloading using wget, I get the following error “Connecting to <URL>.. failed: Connection refused.”. I’m behind a proxy server. How do I fix it?

Answer: Export the http_proxy variable with your proxy server name or ip address and then try downloading as explained below.
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In this article, let us discuss about how to setup tftpboot, including installation of necessary packages, and tftpboot configurations.

TFTP boot service is primarily used to perform OS installation on a remote machine for which you don’t have the physical access. In order to perform the OS installation successfully, there should be a way to reboot the remote server — either using wakeonlan or someone manually rebooting it or some other ways.

In those scenarios, you can setup the tftpboot services accordingly and the OS installation can be done remotely (you need to have the autoyast configuration file to automate the OS installation steps).
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On Linux, you can setup disk quota using one of the following methods:

• File system base disk quota allocation
• User or group based disk quota allocation

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There are four ways to execute a shell script. Each way has it’s own meaning as explained in this article.

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Question: When I’m trying to ssh to a remote server, after I enter the username, it takes a lot of time before it displays the password prompt. Basically, my SSH ( openSSH ) is slow during authentication process. How do I solve this problem?

Answer: If your ssh login from localhost to remotehost is slow, enable the ssh debugging while starting the ssh connection using option -v as shown below.

After it displays the “debug1: SSH2_MSG_SERVICE_ACCEPT received” message, ssh session will be hanging for almost a minute before it continues to the next debug statement.
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