What to do if you forgot the password for your CentOS/Fedora/Redhat machine?? Here are some simple steps to change back the password by entering into single user mode of your machine provided you do not forgotten your grub password if you have set it Reboot your machine Press ‘Esc’ key once grub starts loading Select [...]
How to compile a kernel on a CentOS server? Compiling a kernel on a CentOS server is probably easy than other Operating Systems but still you should take care while selecting modules else the server won’t boot up on the new kernel. New System admins find it difficult to compile a kernel, however, the following [...]
/etc/defaultrouter is the configuration file for default router under Solaris os. The /etc/defaultrouter file can contain the IP addresses or hostnames of one or more default routers, with each entry on its own line. If you use hostnames, each hostname must also be listed in the local /etc/hosts file, because no name services are running [...]
Linux kernel includes magic system request keys. It was originally developed for kernel hackers. However, you can use this hack to reboot, shutdown or halt computer safely (remember safe reboot/shutdown == flush filesystem buffers and unmount file system and then reboot so that data loss can be avoided). This is quite useful when Linux based [...]
Why do server not showing up 4GB of RAM? By default a server supports up to a 4GB of RAM i.e. on a non-PAE kernel. If you wish to add 4GB RAM or more, you will have to install kernel-PAE package which addresses upto 64GB of RAM. Once you install the kernel with the PAE [...]
fuser command displays the PIDs of processes using the specified files or file systems. You can use fuser command to specifies a file on a mounted file system or a block device that is mounted. All processes accessing files on that file system are listed using -k option you can forcefully kill mounted file system. [...]
On running daily lvm snapshot backups via vzdump on OpenVZ servers, I noticed the below Kernel errors in logwatch reports. WARNING: Kernel Errors Present Buffer I/O error on device dm-4, …: 22 Time(s) EXT3-fs error (device dm-4): e …: 60 Time(s) lost page write due to I/O error on dm-4 …: 22 Time(s) This would [...]
This is one the essential and important task. Many time we upgrade our kernel and some precompiled drivers won’t work with Linux. Especially if you have weird hardware; then vendor may send you driver code aka C files to compile. Or even you can write your own Linux kernel driver. Compiling kernel driver is easy. [...]
The ‘uname’ command is use to determine certain system information in all the Linux/Unix flavours like CentOS, Ubuntu, Debian, Fedora, FreeBSD etc. With specific ‘uname’ options, you can display all the details of the current working kernel on the server. To display the working kernel name, version, date and time, system architecture type, use: # [...]
Today I discovered Ketchup, a little command-line tool to manage your Linux kernel sources. If you’re one of the weirdos, who is still compiling his kernel manually for whatever reason (like I do), I can only recommend it. Ketchup nicely eases up the entire process of checking for updates and applying them to your system. [...]
