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Dealing with Runaway Processes

July 14, 2015 – 10:46 pm |

There is no official definition of a “runaway process”. Generally, it is a process that ignores its scheduled priority. It can also be a process that enters an infinite loop. Or it can be a process …

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Unix and Linux network configuration. Multiple network interfaces. Bridged NICs. High-availability network configurations.


Reviews of latest Unix and Linux software. Helpful tips for application support admins. Automating application support.


Disk partitioning, filesystems, directories, and files. Volume management, logical volumes, HA filesystems. Backups and disaster recovery.


Distributed server monitoring. Server performance and capacity planning. Monitoring applications, network status and user activity.

Commands & Shells

Cool Unix shell commands and options. Command-line tools and application. Things every Unix sysadmin needs to know.

Performance »

Collectl & Colplot Sytem Performance Analysis Tools

August 26, 2015 – 11:17 am |

It is not often that I run into Unix performance analysis tool that, a), I haven’t seen before and, b), is worth my attention. Collectl is both. It is a very useful combination of iostat, vmstat, netstat and just about every other ‘stat. All of those standard tools are awesome for getting that specific piece of system performance information, but uniting all that data into one cohesive picture usually requires a Master’s degree in Awk & Sed programming. Read the full story »

Installing Perl Modules with YUM

August 17, 2015 – 5:30 pm |

Just a quick note on how to install Perl modules with YUM. Due to differences in the naming conventions, YUM package name for a Perl module may differ from the the module’s native name in …

Brief Guide to PDSh

August 17, 2015 – 12:53 pm |

PDSh (Parallel Distributed Shell) is a high-performance parallel remote shell utility allowing you to execute commands on multiple remote hosts simultaneously. The utility was originally developed by LLNL and is currently available under GNU CPLv2. …

Find Available IP Addresses

June 18, 2015 – 10:58 am |

After a while, available IP addresses on the subnet may become hard to come by. Whatever spreadsheet you used to track IP allocations is likely out of date. Here’s a simple script that will scan …

Multi-Cluster Ganglia Configuration

June 17, 2015 – 11:28 am |

I’ve discussed Ganglia configuration and RHEL/CentOS installation in the past. The usual structure is where every node belongs to one cluster. Recently I ran into a requirement to have nodes assigned to more than one cluster. …

Enabling dmesg Timestamps in RHEL

June 12, 2015 – 5:04 pm |

By default, CentOS/RHEL dmesg timestamps are disabled. Here are the instructions to enable timestamps and a quick script to display time in a human-readable format.

Raspberry Pi 2 OpenELEC Player

June 10, 2015 – 4:37 pm |

Just some quick documentation, mostly for myself, but feel free to try. This is a Raspberry Pi 2 with OpenELEC. The design is intended for overclocking, good wireless performance, and convenience of dual remotes. This …

Saving Postfix Messages

June 3, 2015 – 3:08 pm |

Sometimes for testing purposes you need to save all messages going through Postfix active queue. There are a couple of ways of doing this.

Detecting Synology NAS with nmap

May 29, 2015 – 3:07 pm |

Just a quick note for myself on how to find Synology NAS servers on the network without having to use the bulky Windows utility that ships with these systems.

Dealing With Prolific Emailers

May 26, 2015 – 2:39 pm |

So you come back from vacation, open Outlook and see thousands of unread emails. Who sends all this stuff? There’s an easy way to identify the sources of this background noise. In Outlook’s inbox, select …

BASH History Control

May 12, 2015 – 12:01 pm |

The standard output of the “history” command will show you the last one thousand commands executed by the user. This is useful, of course, but there are a few issues. Sometimes it’s important to know …

Verify Email SSL Certificate from CLI

May 8, 2015 – 10:36 am |

Just a quick reference for validating SSL certs on mail servers. This is not something I have to do often, but when the need arises, I find myself googling the answer every single time. So …

Extending Swap on LVM2 Logical Volume

May 7, 2015 – 11:16 am |

To grow swap on LVM you will need to temporarily disable the swap LV. This will leave without swap space, which may upset some applications (Oracle). So the first step should be to set up …

Faking the Uptime in Linux

May 4, 2015 – 10:05 pm |

If, for whatever reason, you need to fake the Linux server uptime, there is a hacked kernel module you can use. The instructions are below.

Resetting HP ILO from OS

May 4, 2015 – 11:02 am |

You can use ipmitool package in Linux to reset your HP server’s ILO password. The basic instructions are below.

Removing CTRL-M from Unix Files

April 16, 2015 – 4:44 pm |

This is a simple but annoying and persistent problem: text files edited on Windows and the uploaded to Unix acquire the “^M” character at the end of each line. In my experience, this little problem …

Observium Agent Installation on Pidora

April 13, 2015 – 11:50 am |

Just some quick notes on installing Observium agent on Raspberry Pi running Pidora. Pretty much the same process applies to any Fedora-like flavor.

Log Event Time Distribution

April 2, 2015 – 11:04 am |

When “once in a while” answer is insufficient and you need to know exactly how often a particular event occurs on the system, there are a few easy things you can try from command line.

Late Night Rant #26

March 30, 2015 – 12:30 am |

When you’ve ls’d, grepped, catted, piped and tailed everything on your computer and there is absolutely nothing left to do, there’s always this…

Login Monitor

March 6, 2015 – 12:02 am |

Sometimes after a couple of beers I start feeling paranoid. I make sure the door is locked and check my firewall logs. Here’s a very basic script to monitor your server’s login record and notify you about …

Installing Salt Minion on RHEL5

February 19, 2015 – 10:38 am |

As of recently, python26-distribute has been removed from EPEL5 due to lack of support and attempting to install salt-minion on RHEL5 will throw a dependency error. If you are still running RHEL5, you would need …

Late Night Rant #25b

February 17, 2015 – 5:41 pm |

No sooner than I stopped complaining about HP’s “holy” Web site, I ran into a similar issue with Red Hat’s site. And that doesn’t happen very often. Unlike HP, Red Hat folks tend to take better …

Late Night Rant #25: HP’s Web Site Fail

February 12, 2015 – 6:24 pm | One Comment

I’ve already mentioned my dislike for the epic mess of broken links HP gingerly called its Web site. Nearly a year-and-a-half later the situation did not improve. Actually, it might have gotten worse.