Linux

Articles on Linux, the open source operating system

How to find out files created within a date range, and above a certain size

Submitted by Khalid on

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Looking at the regular weekly backups, I saw a jump in size that was not accounted for by regular normal growth.

ls -ltrh /backupdirectory
...
-rw-r--r-- 1 root root 31G May 25 03:23 backup-2014-05-25.dump
-rw-r--r-- 1 root root 31G Jun 1 03:22 backup-2014-06-01.dump
-rw-r--r-- 1 root root 32G Jul 6 03:21 backup-2014-07-06.dump
-rw-r--r-- 1 root root 41G Aug 3 03:25 backup-2014-08-03.dump
...

How to avoid PackageKit consuming lots of CPU and RAM on Kubuntu 14.04

Submitted by Khalid on

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After upgrading my laptop from Kubuntu 12.04 LTS to 14.04 LTS, I noticed that the laptop runs hotter than usual.

Upon investigating further, I found that PackageKit was the process that was consuming lots of CPU and memory.

For example, here is a sample output from htop, showing packagekitd maxing out one core, and eating up almost a quarter of the laptop's RAM:

How to use strace for a daemon with multiple processes, including children

Submitted by Khalid on

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Sometimes when you are running Linux and have a weird bug, you wish you would know what the process is doing. For example, which files it is opening and such ...

The strace command is very useful.

Use case 1: Simple command as argument

However, its common use cases is when you have a single process running. Usually, you would run strace and your command as an argument, like so:

strace your_program

Use case 2: Tracing a running command

Presentation: OpenWRT, for the KWLUG, August 2014

Submitted by Khalid on

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On August 12th, I did a presentation on OpenWRT for the KW Linux Users Group.

The slides from this presentation are attached below, and the audio for the presentation is available as a podcast.

Hope it is of use for some.

In that presentation I mentioned wrtbwmon, the bandwidth monitoring script for OpenWRT. You can download my modified version from here.

wrtbwmon: A Bandwidth Monitoring Tool for OpenWRT Routers

Submitted by Khalid on

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Years ago, I wrote about the various tools available for monitoring bandwidth usage for individual devices in a home network.

Now, I have a definitive solution that will help with the questions: wrtbwmon. This is based on several variants that are floating around the internet, each a fork of another.

Here is an excerpt from the README file:

Description
===========

Using Linode Dynamic DNS with OpenWRT

Submitted by Khalid on

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If you have a VPS at Linode, then you have free Dynamic DNS. You can use that from a regular Linux machine, or from a router that runs OpenWRT.

This article describes how to setup an OpenWRT router with Linode Dynamic DNS.

First, the script itself, which goes into the file: /etc/custom/linodedns.sh

#!/bin/ash
 
BASE=`basename $0 .sh`
DIR=`dirname $0`

OUTPUT1=/tmp/$BASE-1.out
OUTPUT2=/tmp/$BASE-2.out

# Read the configuration file
CONF=$DIR/$BASE.conf
if [ -r "$CONF" ]; then
  . $CONF
else

Logging with Syslog-NG on OpenWRT

Submitted by Khalid on

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Update 2020-07-09: With the latest 19.07.3, syslog-ng is no longer the preferred option. Instead, read my other article on using rsyslog with OpenWRT.

Update 2014-10-08: If you upgraded to the stable Barrier Breaker 14.07, and Syslog-NG is not available, or if don't want to use Syslog-NG for any other reason, please check our other article on using the built in logging feature of OpenWRT to write the log to a file.

We wrote earlier on OpenWRT on D-Link DIR-835. Now, we need to expand the functionality a bit more.

On OpenWRT, the default logging mechanism is an in-memory circular buffer. The user interface for it is the logread command. The log buffer default size is 16 kB. There are a couple of directives that can be set in the system configuration for OpenWRT, but because of the limited size of flash and the non-permanence of RAM, you need another solution if you want to store logs for anything longer than a day or two.

Syslog-NG

Syslog-NG is a good system logging program that is available for OpenWRT.

Youtube/Flash not working on Semperon under Ubuntu? Use Gnash!

Submitted by Khalid on

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If you are using Ubuntu 12.04 on an older computer with a Semperon CPU, you will soon find that Flash is not working and therefore Youtube videos will not work either.

Adobe Flash built with SSE2 flag

This is because Adobe has build the recent Flash versions with the SSE2 flags enabled, yet many Semperons lack this particular flag.

$ cat /proc/cpuinfo
vendor_id : AuthenticAMD
cpu family : 6
model : 8
model name : AMD Sempron(tm) 2600+
...

Four hours of battery time on a Linux laptop

Submitted by Khalid on

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I previously wrote about reducing CPU usage for Firefox by disabling Firebug. Later, I wrote on disabling the YSlow extension also reducing CPU usage.

Now, the laptop is able to exceed 4 hours of battery time under Kubuntu Linux 12.04:

Four hours, seven minutes:

09:37:27 localhost pm-utils: Power source switched to battery, Battery: discharging, A/C adapter: off-line

Quick How To: Installing OpenWRT on the D-Link DIR-835 wireless router

Submitted by Khalid on

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This is a quick how to for installing OpenWRT custom firmware on a D-Link DIR-835 router.

Though these instructions were tested on the DIR-835, they apply to many other router models from Linksys, Netgear, ASUS, and many other brands.

Check if your hardware is supported

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