Unix Tutorials and HowTos

Question and answer for users of Unix-like operating systems. Topic includes – Unix commands, servers, security, networking, shell programming, troubleshooting and much more ( rss feed ).

I‘m a new FreeBSD Unix system user. How can I find out the process/programs names listing on a certain port on a FreeBSD Unix systems using command line? How do I lookup the process which is currently bound to the given network port on a FreeBSD server?


My OpenSSH server listing on TCP port number 2222. How can I use ssh-copy-id with an sshd server with listing on a different port on a Linux or Unix-like systems?


There are certain files in Ubuntu Linux (or Unix-like systems) that only root user access or edit. How can I edit and/or open files that requires admin (root) access on a Ubuntu Linux?

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I recently switched from MS-Windows server to a FreeBSD Unix server. How can I see list of mounted file systems on a FreeBSD based Unix server using command line options?


I‘m a new Ubuntu Linux user. In Linux, Apple OS X or Unix-like systems, how do I reissue or repeat a long command without retying it?


I need to tunnel X Window securely over SSH bases session so that I run X program on my remote Linux/Unix server/workstation and get back display to my Apple Macbook pro laptop. I tried the ssh -X user@server1 and ssh -Y user@server2 commands on both OS X Mountain Lion and Apple OS X Mavericks/Yosemite. But, I am unable to use the ssh command with X11.

How do I fix this problem on OS X and enable X11 forwarding with ssh command? How do I install XQuartz (X11.app) server on Apple OS X Mountain Lion or Mavericks or Yosemite?


I have a Linux DD-WRT router DHCP server running on my network. How can I force my FreeBSD based dhcp client to get a new lease from this Linux based router? What is the command in FreeBSD equivalent to Windows’ “ipconfig /renew” command?