I recently ran into a problem where one of my CentOS machines was taking a very long time (a couple of minutes) to start the sendmail and sm-client servies at boot time. I found the fix was quite simple. The problem in my case was resolved by making sure the hostname was correctly added to [...]

For whatever reason you may need to free the disk cache at some point. Since Linux 2.6.16 the interface /proc/sys/vm/drop_caches has been available to simplify this process. First we run the sync command before dropping the cache. Doing this will ensure that all memory in the cache is updated and all dirty pages are synchronized [...]

You may already be familiar with NFS and Samba for sharing files over a network. While these are both great distributed filesystem solutions, they require extra configuration and setup overhead in order to get them to work. If you want quick and easy access to a remote filesystem then SSHFS may be your best shot. [...]

An ISO image is an archive file (disk image) of an optical disc using a conventional ISO (International Organization for Standardization) format. ISO image files typically have a file extension of .ISO. Many times is convenient to mount an ISO file directly instead of burning it to a CD first. Not only does this save [...]

At various times it is necessary to restrict the users which can access a certain host. If your network relies on SSH it is as simple as changing an option in the sshd_config configuration file. You will of course need root access to make the necessary changes to this file and eventually reset the SSH [...]

When you run the find command on the root directory of a system you may want to exclude all network filesystems and confine your search to only your local machine. The benefits of this are obvious as it will save you a great amount of time especially if the mounted filesystem is very large. Luckily [...]

The process environment consists of all the individual environment variables which are passed on to the program by the shell when the program is launched. This environment can be read and changed by the program during its execution, and can affect how a program is linked or how it executes. For all these reasons it [...]

There are 2 files available on a Linux system which will give a user a wealth of information about a system. These files, /proc/cpuinfo and /proc/meminfo are written by the Linux kernel and tell you important details about your cpu and memory. Both files are read-only and can be viewed with any text editor. This [...]

SSH allows secure (encrypted and authenticated) connections between two hosts. These connections include terminal sessions, file transfers, TCP port forwarding, as well as X window forwarding which I will be covering here. X forwarding is a form of tunneling that allows you to run a GUI application on a remote machine but let you view [...]

The end of a line in a UNIX text file is designated with the newline character. In Windows, a line ends with both newline and carriage return ASCII characters. If a file is saved in Windows and then moved to a Linux system these carriage returns can cause all sorts of problems. If the text [...]