Linux and Unix Commands

Tips and tricks about Linux, OS X, *BSD and Unix commands. Includes commands, syntax, hacks and much more for both new users and sysadmins ( rss feed ).

whereis command

I am a new Linux and Unix-like system command line user. How do I find and locate the binary, source, and manual page files for a given command?


I would like to see detailed information on the history of yum transactions such as updates, deleted packages, and other information. How do I see history of yum commands on CentOS / RHEL 6.x based server? How do I undo or redo or rollback packages using yum command?


I recently learned that “wget” can continue getting a partially-downloaded (resume download) file. I am unable to find wget command on Mac OS X. How do I install install wget on Mac OS X (Mountain Lion/ Mavericks / Snow Leopard)? How can I install wget in Mac OS X without 3rd-party repo such as Homebrew or MacPorts?


I see lots of seasoned admins and cloud provider wrapper scripts use ssh client command as follows in shell:

ssh --

What the double -- does here? Why it is used in this shell command and why not just use the following?



How do I install Go language on Apple Mac OS X? How to setup GO lanuage on Mac OS X? How do I install Go language version 1.2+ on OS X?


CentOS Linux v6.5 has been released and available via repos for immediate update. The new version includes several hundred bug fixes for, and enhancements to the Linux kernel. How do I upgrade from CentOS Linux version 6.0 / 6.1 / 6.2 / 6.3 or 6.4 to the latest version 6.5?


I manage MS-Windows server and recently started to play with OpenBSD server. How do I reload or restart the dhcpd server on OpenBSD using shell command line option?

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