A semaphore is a mechanism that allows contending process or thread to alter, monitor queries, and control shared system resources. A semaphore is a solution to race condition in multiprocessing system. Race condition occurs when multiple processes try to access shared resources. [...]
How to Check LUN or SAN Disk in Linux
When you are working in a storage environment, it is often desirable to add, remove or re-size storage devices. Once storage is allocated we need to scan and verify allocated storage SAN disk. In this article, I will show commands to check/identify [...]
How to Check NFS Client Connection with Rpcinfo Command
Rpcinfo command shows each RPC-based service locally or on a remote Linux machine. In this article, I will show you a couple of commands to troubleshoot NFS related issues. Check NFS service status Issue the following command on the NFS [...]
How to Check Linux Version from Command Line
How to find Linux OS name and version? There are lots of Linux distros like Debian, Ubuntu, CentOS, Mint, Arch, Fedora, RHEL and it's very important to know os version while doing OS update or package updates. This tutorial we [...]
Everyday Linux ps command Examples for System Admin
Linux/Unix system administrator should be very proficient in performance monitoring and tuning. For performance monitoring, administrator should understand how various Linux component and processes works (like CPU, Memory, I/O and Network). Process status (PS) is a command used to display current [...]
How to Enable SSH Log and List Failed Login in Linux
As we know SSH protocol provide remote login facility and hence it is important to maintain the login logs. System admin can achieve this by configuring in syslogd services. In Linux, syslogd is the unix logging service which maintains the logs [...]
How to Configure Netdump Client on Linux
Netdump is used to transport kernel core memory images to a remote server during a crash. In this article, I will show you some useful commands to setup netdump on Linux. 1) Check Netdump Package To check whether “netdump” package has already [...]
How to List Linux Pci Devices Using lspci Command
The peripheral component interface is a computer bus used for attaching the hardware devices in a computer. 'lspci' command is used in Linux operating system to display all the information about these PCI buses of the system and devices which are [...]
Step by Step Guide to Create LVM Mirroring in Linux
In the computer world, storage is the most important factor. If data is lost, then everything is lost for the organization or company. Initially, data is stored in normal disks, it does not have the flexibility to manage the data and [...]
How To Use Screen And Script Command In Linux
The screen is a terminal multiplexer. Using this, you can run any number of console-based-applications, interactive command shells, course-based applications, etc. You can use screen to keep running program after you accidentally close the terminal, or even after you log out and [...]
Rsync Examples to Transfer Files in Linux
In this tutorial, I will show you some rync examples to transfer (synchronize) files and directories to/from the local/remote Linux/Unix systems using rync command. Rsync can recursively copy files and directory, copy symlinks, preserve (permissions, group, modification time and ownership) [...]
How to Use Linux Route Add Command
Routing is the way that computers communicate on a local network or over the internet. When you want to talk to someone, you need to know his position and how you can join it. To communicate over a network (big [...]
How to Use df Command to List Filesystem Mount Points
In Linux df command is used to display the amount of total and free disk space available on the mounted file systems. Using df options you can find used blocks, inodes and free space available in the file system. In [...]
How to Move User Account from Linux Server to Another Server
This article I will show you how to cleanly moved user accounts from one Linux server (say Redhat or centos) to another server and its all related files. Users can be people, accounts tied to physical users or accounts which [...]