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 setting up a new FreeBSD server. I do not want to use a default root user who has full system access. How can I setup and grant sudo privileges to users on a FreeBSD VPS or server?

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I‘m a new Linux / Unix system user. How can I set encrypted tunnel between my desktop/laptop computer and server in a remote data center to bypass the limits in a network? How do I create a reverse SSH tunnel on Unix-like systems?

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How can I analyze line rate taking log file as input on a Linux system? How do I find the IP flooding my Apache/Nginx/Lighttpd web-server on a Debian or Ubuntu Linux?

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I have created/launched Amazon Machine Image (AMI) instance powered by a CentOS/RHEL/Red Hat Enterprise Linux. How can I connect to my instance using OpenSSH Linux/Unix/OSX ssh client?

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I‘m installing FreeBSD 10 Xorg and xfce4 desktop. But, getting the following error:

(EE) Failed to load module “fbdev” (module does not exist, 0)

How do I fix this problem on FreeBSD 10 amd64 based system?

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I am a new Ubuntu Linux and bash shell user. I also know how to redirect output from display/screen to a file using the following syntax:

cmd > file
ls > file

However, some time errors are displayed on screen. How do I store and redirect output from the computer screen to a file on a Linux or Unix-like systems?

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I‘m a new Linux system user. I need to cleanup in a download directory i.e. delete all files from ~/Downloads/ folders except the following types:

*.iso – All iso images files.
*.zip – All zip files.

How do I delete all file except some in bash shell on a Linux, OS X or Unix-like systems?

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