How to use high-resolution gettimeofday in Perl

In order to use microsecond-resolution time (e.g., gettimeofday) in Perl, you first need to install Time::HiRes CPAN module.Read more »

How to enable ssh login without entering password

Assume that you are a user "a" on host A, and wish to ssh to hostB as user "b" without entering its password.  Do the following while logged in as user "a" on hostA.Read more »

How to reload sysctl.conf

Linux provides a sysctl interface for checking and modifying kernel parameters which are listed under /proc/sys directory. You can persistently set those kernel parameters via /etc/sysctl.conf. Read more »

How to install OpenVPN on CentOS/Redhat

In order to install OpenVPN on CentOS/Redhat, you first need to set up a RPMforge repository which contains many additional software tools in rpm package format for these distributions.Read more »

How to mount NFS share as a regular user

1. On the NFS client machine (e.g., 10.1.1.20), update /etc/fstab as root.Read more »

How to set up a PPTP VPN connection between Linux and Windows XP

Point-to-Point Tunneling Protocol (PPTP) is a VPN tunneling protocol based on a client and server model. Microsoft Windows comes with a built-in PPTP client software, and so PPTP VPN is popular among Windows-running computers. PPTP server and client software is also available on Linux platform.Read more »

How to add a secondary hard disk to Xen DomU

On Dom0, do the following:Read more »

How to convert ps/eps file into jpg image file

You can use gs to convert a ps or eps file into a jpg image file in Debian/Ubuntu.Read more »

How to use git behind proxy on Ubuntu

The following fix has been confirmed to work on Ubuntu server 11.04 and 11.10.Read more »