How to backup a hard disk on Linux

If you would like to backup your hard disk, there is a simple way to do it by using "dd" command. The dd command utility is used to copy files or disk images from one location to another. Using dd, you can backup an unmounted disk as a (compressed) disk image which is then stored in a separate local or remote disk. Here is how to backup and restore a hard drive using dd command.Read more »

How to diff remote files over ssh

Diff command line utility compares contents of two files (or directories), and shows how they differ line by line. It's straightforward to use diff if both input files are located on local host. But what if input files located on two different hosts? You can actually diff remote files over ssh. Here is how.Read more »

How to benchmark virtual machines

When you are comparing various hypervisors, you may want to compare the performance of virtual machines (VMs) running on different hypervisors. Also, if you are comparing various public cloud providers, you will want to benchmark VMs offered by available providers. Whatever the reason may be, it is useful to know how to benchmark VMs properly.Read more »

How to limit the CPU usage of a Linux process

If you are a Linux system admin, there are cases where you would like to limit the CPU usage of a certain process such that at no time does the process eat up more than X% of CPU resource. cpulimit is a Linux program that can do exactly that, i.e., limiting the CPU usage of a Linux process in percentage. It monitors the CPU usage of a specified process as a daemon, and adjusts its CPU utilization dynamically.Read more »

How to backup files to a remote FTP server using lftp

lftp is a command-line FTP client with several advanced file transfer features. For example, lftp can upload or download a whole directory tree recursively and selectively, or resume interrupted file transfers. A popular use case of lftp is to mirror local files or folders to a remote FTP server. While rsync is a popular mirroring software tool, it uses its own file synchronization protocol, and so does not work over FTP.Read more »

How to synchronize time with NTP

NTP is a networking protocol which enables one to synchronize clock among different computers using IP packets. NTP is commonly used when one maintains a cluster of hosts to operate compute and storage cloud in data centers. NTP is capable of compensating for variable latency over networks, and can achieve clock synchronization with 1 millisecond accuracy in ideal conditions. If you would like to synchronize time with NTP, follow the steps below.Read more »

How to convert TIFF files to PDF format on Linux

TIFF (Tagged Image File Format) is a popular image file format. Unlike other types of image files, a TIFF file can contain multiple images (e.g., multi-page document scan) in it. TIFF editor software such as GIMP is able to support such multi-page TIFF files. If you would like to convert a TIFF file to PDF format on Linux, you can follow the instructions below.Read more »

How to convert xlsx files to xls or csv format on Linux

The xlsx file name extension is a new file format based on XML, used by Microsoft Office Excel 2007 spreadsheet application. The letter "x" appended to the existing "xls" extension used by earlier versions of Excel, signifies that the format is based on XML. If you would like to open or edit an xlsx file created by Excel 2007, on an earlier version of Excel or any other spreadsheet application, you need to convert xlsx files first.Read more »

How to edit a PDF file for free

pdftk (PDF Toolkit) is a command-line tool which enables you to edit PDF files. pdftk is freely available on Linux, MS Windows, MacOS X and FreeBSD. So using pdftk, you can edit PDF files for free. If you would like to install pdftk on Linux, proceed as follows.Read more »

How to install dos2unix on Linux

DOS-based text files use a pair of carriage return (CR) and line feed (LF) as a new-line delimiter. On the other hand, UNIX-based text files simply use LFs to terminate each line. In order to convert a text file from DOS format to UNIX format, you can install the following package.Read more »