Posts Tagged ‘ Linux ’

Being the administrator of a large Linux shop, I have had to extend the filesystems on the Red Hat Linux server a few times. Each time I had the opportunity to extend the filesystem, I found that I struggled to remember the commands and steps. This is because Linx is a very command line...
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A funny thing happened to one of my Red Hat 5 Enterprise servers after applying the errata. I rebooted the servers as usual after applying the updates, and they came up just fine. But unfortunately I was not able to logon remotely via ssh to a server. I tried various different accounts including root,...
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The administrative account ‘root’ is the most powerful user in Linux and Unix. This account is created by default during installation of the operating system. Most security consultants will recommend that the root account be deleted or renamed. This is to make it harder for a hacker to find out what a valid user...
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I have created a step by step approach to troubleshoot a problem with performing yum update and how to rebuild the rpm database. I received and error while trying to update the Redhat Enterprise 5 server kernel using yum update. Looking at the output of yum update it seems that the dependency mkinitrd was...
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Red Hat Linux can be booted into rescue mode from the installation CD, or any other boot method instead of the system’s hard drive. This also applies to other versions of Linux such as Fedora and Centos. The rescue mode is provided for troubleshooting and repair purposes. This is really handy when the OS...
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Use the command uname to print system information in Linux. # uname -r 2.6.18-194.32.1.el5 The –r option will print the kernel release. # uname -s Linux -s prints the kernel name. # uname -n mycomputer.wiivil.com Print the node name or hostname. # uname -p i686 Print the processor type, the i686 signifies a 32...
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I came across this issue on my newly built Solaris 10 server. I was able to ping a remote machine by Ip address, but not by its hostname. This indicated that I had the correct route and gateway. Using nslookup and dig I verified that the DNS servers were resolving the hostname to IP...
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I ran into this error while trying to mount a NFS directory on a remote server from my Vmware ESX4 server. My Vmware esx server is called esx4-server and the remote NFS server is called remote-server. I executed the mount commant and got the below error. # mount -t nfs remote-server:/home/andrew/mnt mount.nfs: Input/output...
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In the past I have written articles about how to create a RDM to LUN disk mapping for VMware ESX 3. http://www.gamescheat.ca/2009/10/scripts-to-automate-the-process-of-identifying-and-compiling-an-rdm-to-lun-mapping-list-for-vmware-esx-30/ and http://www.gamescheat.ca/2009/10/how-to-identify-and-compile-an-rdm-to-lun-mapping-list-for-vmware-esx-30/ The procedure to identify the path for the RDM (raw disk mapping) to LUN (disk on SAN) on Vmware ESX 4 is different from Vmware Esx 3. There are a...
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List the status of all swap areas. # swap -l swapfile dev swaplo blocks free dev/dsk/c0t0d0s1 32,9 16 8425712 8425712 The output has five columns: path The path name for the swap area. dev The major/minor device number in decimal if it is a block special device; zeroes otherwise. swaplo The swaplow value for...
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