Flush DNS cache
This morning I was doing some work with one of my website transfer and to see the changes on my MacBook laptop I knew I would need to flush the DNS cache so I wouldn’t have to wait for the cache to expire. So for anyone else who needs to know the commands here they are: OS X <= 10.5.1 (Mac OSX versions 10.5.1 and before) lookupd -flushcache OS X >= 10.5.2 (Mac OSX Leopard) dscacheutil -flushcache In Linux, the […]
Read MoreLinux Configuration and Diagnostic Tools
untitled System and Network Configuration * linuxconf – A GUI interactive interface available on Redhat 6.0 or later which includes netconf configuration. * netconf – A GUI interactive interface available on Redhat 6.0 and later. * kbdconf – A Redhat Linux tool which configures the /etc/sysconfig/keyboard file which specifies the location of the keyboard map file. This is a GUI based tool. * mouseconfig – A Redhat Linux tool used to configure the /etc/sysconfig.mouse file. This is a GUI tool. […]
Read MoreAuto lock your Mac when you walk away
We geeks all have some sort of bluetooth device on us like your Nokia N80 or your new iPhone (which I will be getting and LOVE) so why not take advantage of one of these as a beacon to your computer. With a small application you can set your computer to detect the proximity of your device and perform actions based on when it comes in or goes out of range. I’m using the free utility Proximity to do the […]
Read MoreGive me the most current file
I needed a quick way to maintain a current symlink to the most recent file by time stamp. Here’s one way to do it: ls -t1 *.jpg | head -1 | xargs -i ln -sf {} current.jpg
Read More#!/bin/bash
I think the number one skill a sysadmin should have is a solid understanding of shells and shell scripting. The Advanced Bash-Scripting Guide is a good place to start or take a refresher. From the introduction: A working knowledge of shell scripting is essential to anyone wishing to become reasonably proficient at system administration, even if they do not anticipate ever having to actually write a script. Consider that as a Linux machine boots up, it executes the shell scripts […]
Read More10 mental blocks keeping you from being a kick-ass sysadmin
Ok, it’s actually an article about 10 Mental Blocks to Creative Thinking but isn’t creative thinking a huge part of being a kick-ass sysadmin? Here’s what I thought of when I read each point, but I highly recommend that you read the whole article and look for ways it applies to you. In terms of what mindset you should be in: There is almost always more than one right answer. Don’t be so rigid with your logic that you become […]
Read MoreService/Daemon Management
restarting/stopping/starting a service On any init.d based linux distro you can restart a service with the following… /etc/init.d/serviceName restart You may replace ‘restart’ with ’stop’ or ’start’ (and in some cases ’status’). Forcefully stopping a service killall processName Killing on instance of a service kill pid The pid can be gathered by either top or ps Disabling/adding/listing services chkconfig –list displays all the services and if they are set to run in different runlevels use the –del daemonName to remove […]
Read MoreUser Management
useradd useradd userName then run “passwd userName” to set the new users pw passwd passwd username will ask for the new pw twice
Read MoreFile Permissions
Listing Permissions ls -al will display all files in a list with their owners and permissions -rw-r–r– 1 irq13 irq13 1006 Jan 24 10:16 .bashrc Now to break down the above example… -rw-r–r– is the permissions area. The first – would be d if the item is directory, otherwise it will be -. The second 3 dashes indicate read/write/execute for the owner, the second is r/w/x for the group and third is r/w/x for everyone else. The next number is […]
Read MoreAdditional command operators
ps | grep ssh — only display lines that contain ssh ; used to “stack commands” or issue multiple commands on 1 line. cd ..; ls & puts a command in the background. Will let you know when the command is finished > write what is displayed on the screen from a given command to a text file ls -alh /root > /root/myRoot.txt >> appends screen output to an existing file
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