System Administration

Disk and Partition

  1. Checking Disk Usage Examples
  2. Unable to open /dev/sdb with fdisk

File Handlers

  1. Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS
  2. Mount an ISO File in Linux
  3. Making ISO using mkisofs


  1. Tweaking the Linux Kernel to manage memory and swap usage
  2. Clearing memory cache
  3. Finding the maximum memory used by your Application

Nagios and Plugins

  1. Installing Check Disk IO Plugins via NRPE on CentOS 5
  2. Incorporating PNP 0.4.x (PNP is not Perfparse) with Nagios 3 and CentOS 5
  3. Installing and checking /proc/mount using Nagios Plugins on CentOS 5
  4. Installing check_mk for Nagios on CentOS 5


  1. Using TurboVNC 0.6 and VirtualGL 2.1.4 to run OpenGL Application Remotely on CentOS

Kick Start

  1. Basic Kickstart on CentOS 6 (Part 1)
  2. Basic Kickstart on CentOS 6 (Part 2)


  1. Recommended /etc/sshd_config parameters for OpenSSH
  2. Speeding up SSH connections
  3. Automate pushing of ssh-copy-id to multiple servers
  4. Helping users to SSH without password into the Compute Nodes manually
  5. SSH Login without Password
  6. Reinstating user password-less access to compute nodes
  7. Building Public Key, SSH Private Key and Authorized Key
  8. Unable to open a connection to your SSH authentication agent
  9. SSH and X-Forwarding on CentOS 6
  10. Allow SSH Root Login From Selected IP Addresses
  11. How to prevent SSH from disconnecting

Performance Monitoring

  1. Using mpstat to display SMP CPU statistics
  2. Basic Overview and use of NMON on CentOS 5
  3. Using strace as a troubleshooting tool
  4. Compiling Valgrind on CentOS 5
  5. Brief overview of Valgrind usage
  6. Using iostat to report system input and output
  7. Using qperf to measure network bandwidth and latency

Performance Tuning

  1. Using Tuned to tune CentOS 6 System
  2. How is the nproc hard limit calculated and how do we change the value on CentOS 7


  1. Configuring CentOS 5 as an SMTP Mail Client with sendmail


  1. Configuring OpenLDAP on CentOS 6 (Part 1)

Environment Modules

  1. Installing and Configuring Environment Modules on CentOS 5
  2. Usage of Environment Modules on CentOS and in Cluster
  3. Installing and Configuring Environment Modules on CentOS 6


  1.  Speeding up kernel crash hang analysis with the kernel log

General Linux Tools

  1. Using the command “ls” options and arguments
  2. MobaXTerm a Swiss-Army Knife for Remote Computing
  3. Unpacking file with tbz extension


  1. Fixing out of memory Issues in Rsync


  1. Disable SElinux in CentOS 7

Configuration and Hardware

  1. Using dmidecode to find hardware information
  2. Massive DNS Requests caused by IPv6
  3. Tools to Show your System Configuration


  1. xRDP Connection Errors on CentOS 6
  2. Fixing Authentication is required to set the network proxy used for download packages on CentOS 6
  3. xrdp_mm_process_login_response: login failed on CentOS 6

NFS Performance and Issues

  1. Using nfsstat to troubleshoot NFS performance issues
  2. showmount fails with clnt_create: RPC: Program not registered from a NFS client communicating with a NetApp filer
  3. mount.nfs: requested NFS version or transport protocol is not supported


  1. Using xsos to summarise System Information


  1. timeout in locking authority file /home/user1/.Xauthority


  1. YumRepo Error: All mirror URLs are not using ftp, http[s] or file