Stefan Durand

My name is Stefan, I'm the admin of LinuxScrew. I am a full-time Linux/Unix sysadmin, a hobby Python programmer, and a part-time blogger. I post useful guides, tips, and tutorials on common Linux and Programming issues. Feel free to reach out in the comment section.

Home » Articles by: Stefan Durand

How to assign range of IP addresses in Linux?

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As we know Linux allows to assign almost unlimited number of IP addresses to its interfaces. Such additional IPs applied to the same NIC are known as secondary IP addresses or just secondaries. Some time ago i faced a problem on how to apply about 500 IP addresses to one Linux box and then ensure that all of them get online after Linux reboots. There are several ways to accomplish this taks so i would like to share them all. Shell script with ifconfig commands … Read more

Home » Articles by: Stefan Durand

How to monitor traffic at Cisco router using Linux (Netflow)

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By default Cisco IOS doesn’t provide any traffic monitoring tools like iftop or iptraff available in Linux. While there are lots of proprietary solutions for this purpose including Cisco Netflow Collection, you are free to choose nfdump and nfsen open source software to monitor traffic of one or many Cisco routers and get detailed monitoring data through your Linux command line or as graphs at absolutely no cost. Below is beginner’s guide that helps to quickly deploy netflow collector and visualizer under Linux and impress … Read more

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The easiest way to split and merge pdf files in Ubuntu

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The easiest way to split, merge or edit pdf files in Ubuntu is to use pdftk utility. This rather old (latest version was released in 2006) but still simple and powerful program can be installed in Ubuntu (Debian or any deb-family Linux distribution) by the following command in terminal: sudo aptitude install pdftk (if you run Fedora, RedHat or CentOS use this one: sudo yum install pdftk) Split large pdf into many one-page files: pdftk largepdfile.pdf burst (as the result you will get many small … Read more

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Split huge files in Ubuntu or any other Linux distro

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Recently I’ve bought WD TV media player for streaming full HD movies (primarily in 1080p resolution) to my home TV from external storage like usb HDD or ipod classic. You might already know that size of average HD movie rip is more than 4GB (e.g. full HD Avatar movie image is literally 21 GB mkv file) so it’s just impossible to store such huge files on any FAT32 formatted HDD or ipod. My ipod classic 160 GB is windows formatted so it uses FAT32 filesystem … Read more

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Install Windows after Ubuntu Lucid Lynx

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Sh*t happens. There is no more applications to manage my 6th generation iPod Classic 160 GB under Linux/Ubuntu. I have to install Windows as the second operating system along with newly installed Ubuntu Lucid Lynx (it rocks but this is for another post) to run iTunes. For rather long time I’ve been using gtkpod, amarok, banshee, exaile or rhythmbox to sync my ipod under Linux/Ubuntu and load my music collection there. As we all know The Elder Brother Apple fights with interoperability and makes ipod/iphone users … Read more

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Fastest way to create ramdisk in Ubuntu/Linux

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I hope many of you will agree that sometimes it’s really good idea to have some small amount of RAM mounted as a filesystem. It may be necessary when running some bash or perl script that handles, say, thousands of small files so it’s much more effective not to waste computer resources on reading/writing data on hard disk but keep those files directly in memory. This idea is known as Virtual RAM Drive or ramdisk and can be setup in Ubuntu or almost any other … Read more

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Best of Linux Cheat Sheets

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Below list of Linux cheat sheets can be used by everybody who administer Linux operating system including beginners/newbies and bearded gurus. PDF | Command Line Interface (CLI), Security, Networking Unix/Linux Command Reference by fosswire.com THE ONE PAGE LINUX MANUAL (A summary of useful Linux commands) LINUX System Call Quick Reference LINUX Admin Quick Reference Linux quick reference card Linux Shell quick reference guide Linux Security Quick Reference Guide tcpdump cheat sheet Wireshark display filters Netcat cheat sheet HTML | CLI, Gnome/KDE DOS to Linux cheatsheet … Read more

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13 Linux lethal commands

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[digg-me]In this post I will collect all commands which SHOULD NEVER be executed in Linux. Any of them will cause data loss or corruption, can freeze or hang up running system. NEVER RUN THESE COMMANDS IN LINUX BOX CLI! Even if somebody advises you in forum/im to do it. 1. Any of these commands will erase everything from your home directory, root or just will clear up whole disk: sudo rm -rf / rm -rf .* dd if=/dev/zero of=/dev/sda mkfs.ext3 /dev/hda whatever > /dev/hda cd … Read more

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Faces behind Linux — Part #1

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What/who you imagine when you hear the names “Ubuntu”, “Debian”, “Slackware”, etc?  Is this tux, penguin, disribution logo? Have you ever wondered who is behind certain Linux distribution? Ian Murdock (left) founded Debian while a student in 1993. He named Debian after himself and his then-girlfriend Debra, now his ex-wife, thus Deb(ra) and Ian. From Ian’s blog: Debian was one of the first Linux distributions and arguably the first open source project that explicity set out to be developed in a decentralized fashion by a … Read more

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Tiny bash scripts: check Internet connection availability

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Sometimes it is necessary to check whether server you want to run some big bash script is connected to Internet. Usually it makes sense while running scripts periodically using cron.  Below is the tiny bash script for this purpose: #!/bin/bash WGET=”/usr/bin/wget” $WGET -q –tries=10 –timeout=5 http://www.google.com -O /tmp/index.google &> /dev/null if [ ! -s /tmp/index.google ];then echo “no” else echo “yes” fi As you see it tries to download google’s index page, if it’s not empty script returns “yes”, if there is not Internet connection … Read more