I am a new Unix / Linux user. I am using whatis command to find man pages. But, I noticed that some man pages have a common names. For example, when I run whatis printf:
Outputs:
printf (1) - format and print data printf (1p) - write formatted output printf (3) - formatted output conversion printf (3p) - print formatted output printf [builtins] (1) - bash built-in commands, see bash(1)
How do I access overlapping man pages and what is the meaning of (1), (1p), (3), and so on?

Read answer to: "Linux / Unix: View Overlapping Man Page With Same Names"

   

How do I mount an ISO image in OpenBSD operating systems using command line options?

Read answer to: "OpenBSD: Mount An ISO Image Command"

   

I am a network admin who recently made the switch from MS-Windows to Ubuntu Linux. I need to use Java and Firefox web browser plugin to run java applet. I am unable to access many devices such as Firewall appliance, LBS/VPX, and network equipments due to Ubuntu's incompatible openjdk and icedtea plugin. I also searched software center but unable to find Oracle Java 7. How do I install Oracle Java 7 and get rid of this incompatibility problems on Ubuntu Linux amd64 v12.04 LTS or v13.04+?

Read answer to: "Ubuntu Linux: Install Latest Oracle Java 7"

   

I have installed Debian or Ubuntu Linux on Dell Inspiron / Latitude / Precision / Vostro laptop. How do I see the current CPU temperature? How do I control and see fan status on Dell laptop?

Read answer to: "Linux: Dell Laptop Fan Control And Get CPU Temperature"

   

I am a new Linux user. I use scp to upload files to net-storage provided CDN company. I do not want to overwrite the existing files. How can I prevent overwriting of files when using scp command under Linux, Mac OS X or Unix like operating systems?

Read answer to: "scp: Do not Overwrite Existing File On Linux or Unix System"

   

I am unable to find Google Chrome Browser in Ubuntu software center. How do I install Google Chrome in Ubuntu version 12.04 LTS or v13.04 using command line options?

Read answer to: "Ubuntu Linux: Install Google Chrome Browser Command"

   

How do I install wake on lan client under Ubuntu Linux desktop to wakeup Unix or Linux based servers?

Read answer to: "Ubuntu Linux: Install Wake On Lan Client For Server"

   

The first-person shooter Half-Life 2 released for Steam on Linux. I truly enjoyed Counter Strike, and I am going to install Half-Life 2 this weekend.

Read more: "Download of the day: Half-Life 2 For Steam on Linux"

   

Recently Debian Linux version 7.0 ("Wheezy") released. This version shipped with many new features - improvements to multimedia support, improved security through hardening flags and the OpenStack suite and the Xen Cloud Platform to name a few. How do I upgrades from Debian Linux version 6.x.x (squeeze) to the latest version 7.0.0 wheezy using command line options? How do I upgrade my Debian 6.x server to 7.x over the ssh session?

Read answer to: "Debian Linux: Upgrade v6.0.x Squeeze to v7.0.0 Wheezy"

   

I need to clean up my backups stored on the nas server. I need to free up the disk space. How do I find out all hidden dot directories such as /nas01/backups/home/user/.gnome/, /nas01/backups/home/user/.gnome/ and so on and delete then in a single pass using Linux or Unix command line option? Please note that I do not want to delete nested hidden directories such as /nas01/backups/home/user/data/.xml, /nas01/backups/home/user/foo/bar/.level/.levle2/ and so on.

Read answer to: "Linux / Unix: Find All Hidden Dot Directories and Delete"

   

I recently added SSD to my home server and reloaded the operating system. However, when I try to access my dm-crypt based old disk, I am getting the following error: Reading all physical volumes. This may take a while... WARNING: Duplicate VG name server01: Existing bc7YA8-eEXt-1aA1-OHTr-zJkA-ucd0-DsbRTc (created here) takes precedence over RIKiar-w3MG-Gzh5-VFWq-bkRT-9IFc-ia8k87 WARNING: Duplicate VG name server01: Existing bc7YA8-eEXt-1aA1-OHTr-zJkA-ucd0-DsbRTc (created here) takes precedence over RIKiar-w3MG-Gzh5-VFWq-bkRT-9IFc-ia8k87 Found volume group "server01" using metadata type lvm2 Found volume group "server01" using metadata type lvm2 The problem is my volume group. I set to to server01 on both old and new hard disk. How can I rename old LVM2? How do I access my old hard disk?

Read answer to: "Linux WARNING: Duplicate VG name server1 LVM2 Error and Solution"

   

Debian GNU/Linux version 7.0 Wheezy has been released ( jump to download ) after many months of constant development and available for download in various media format. Debian 7.0 is a free operating system includes various new features such as multiarch support, several specific tools to deploy private clouds, an improved installer, and a complete set of multimedia codecs and front-ends which remove the need for third-party repositories.

Read more: "Download of The Day: Debian Linux 7 ( Wheezy )"

   

I would like to see the Time-to-live (TTL) value for a 'AAAA' and A record for domains. How do I see Time-to-live (TTL) for a DNS record under Unix or Linux operating systems using command line options?

Read answer to: "Linux / Unix: Dig Command Find Out TTL (Time to Live) Value For DNS Records"

   

My iptables based firewall allows only port TCP 80 and 443. I also need tcp port # 22, but I do not have static IP at my home. How do I open and close TCP port #22 on demand under Debian or Ubuntu Linux based server systems? How do I install a port-knock server called knockd and configure it with iptables to open tcp port #22 or any other ports?

Read answer to: "Debian / Ubuntu: Set Port Knocking With Knockd and Iptables"

   

How do I install rubygems package manager for Ruby on rails (RoR) under Debian or Ubuntu Linux operating systems?

Read answer to: "Debian / Ubuntu: Install gem The FrontEnd To Rubygems"

   

Logstalgia (also known as ApachePong) is a very powerful and handy app. It is a website access log visualization tool. It is an extremely useful tool to give you look at your web server traffic. I often use this kind of software to justify and convince my clients and/or boss that we need more servers to handle traffic. It streams Apache / Lighttpd / Nginx web-server access logs as a pong-like battle between the web server and a never ending torrent of requests.

Read more: "Apache / Nginx: Visualize Web Server Access Log In Real Time"

   

I am a new vi / vim text editor user and I know how to quit without saving changes. What if I want to wipe out all of the edits I have made in a session and get back to the original file? How do I wipe all changes since opening a file?

Read answer to: "Vi / Vim: Wipe and Undo All Changes Since Opening a File"

   

You can send visitors to different servers based on country of their IP address using Amazon Route 53 cloud based dns server. For example, if you have a server in Amsterdam, a server in America, and a server in Singapore, then you can easily route traffic for visitors in Europe to the Amsterdam server, people in Asia go to the Singapore server and those in the rest of the world be served by the American server. This will results into the various kinds of benefits such as:

1. Better performance as you are sending web site visitors to their nearest web server.
2. Reduced load on origin.
3. Geomarketing/online advertising.
4. Restricting content to those geolocated in specific countries (I am not a big fan of DRM).
5. In some cases you can get potentially lower costs and more.

In this post, I will explain how to configure and test GeoDNS using AWS Route 53 service.

Read more: "Amazon AWS Route 53 GEO DNS Configurations"

   

I made changes to the httpd.conf file. How do I reload the new config changes without restarting the Apache 2 web server under Debian / CentOS Linux operating systems?

Read answer to: "Apache 2: Reload HTTPD Configuration File Without Restarting Apache Config Changes"

   

I am a new Linux user. I have text files with lots of empty lines. How do I delete all empty lines under Linux or Unix operating systems?

Read answer to: "Linux / Unix: Shell Remove Empty Lines"

   

How do I match dot files under Unix / Linux using bash shell? Why .* considered as harmful when matching dot files under bash shell?

Read answer to: "Bash: .* Considered Harmful To Match Dot Files. Why?"

   

I am a new Unix user. How do I rm (remove) all files in a directory called personal-files under Unix like operating systems?

Read answer to: "HowTo: Unix rm All Files In a Directory"

   

How do I find out number of arguments passed to my bash function called foo() under Unix like operating systems?

Read answer to: "Bash Function: Find Number Of Arguments Passed"

   

I have the following message whenever I use the apt-get command under Debian or Ubuntu Linux:

The following packages were automatically installed and are no longer required: libaccess-bridge-java libjs-mochikit python-cheetah libjs-excanvas libaccess-bridge-java-jni sabnzbdplus-theme-smpl tzdata-java ca-certificates-java Use 'apt-get autoremove' to remove them. 0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.

How do I fix this issue? Is it safe to remove all unwanted packages?

Read answer to: "The Following Packages Were Automatically Installed And Are No Longer Required Warning"

   

How do I install Java and C/C++ integrated development environment called Eclipse under Debian GNU/Linux squeeze v6.xx?

Read answer to: "Debian Linux Install Eclipse Java / C / C++ IDE"

   

How do I check if a directory exists in a shell script under Linux or Unix like operating systems?

Read answer to: "HowTo: Check If a Directory Exists In a Shell Script"

   

Writing shell scripts in vim I usually go search for functions or something. Copy lines and then go back to where I was and modify the code. However, I need to manually navigate way back to the previous / last position. How can I automatically go back to where I was when I started my search operation under vim?

Read answer to: "VIM: Jump Back To Previous or Last Cursor Position"

   

I need to parse the following text file: # example.net config user = www30021 group = ftp30020 uid = 30021 gid = 30020 tmp_path = /netapp42/shared/www/images/host.example.com/tmp.bin tmp_perms = defaults,nodev,nosuid,noexec jail = on location = /jails/apache/h/host.example.com/ sftp = on ftps = off php-cgi = on perl-cgi = off I need to find out value for each field and remove any blank spaces / white spaces from the field. How do I solve this problem using awk under Linux or Unix like operating systems?

Read answer to: "AWK: Remove All Blank Spaces From String / Field"

   

I am the small business owner and runs my own web-site. I have noticed increased cracking activity against by blog. What's the best way to block WordPress URLs such as example.com/blog/wp-login.php and example.com/blog/wp-admin/ in the nginx web-server?

Read answer to: "Nginx: Block URL Access (wp-admin/wp-login.php) To All Except One IP Address"

   

I am under DoS attack. My cloud based server hosting company asked me to enable TCP SYN cookie protection to save my domain from SYN Attack. How do I turn on TCP Syn cookie protection under Ubuntu or CentOS Linux based server?

Read answer to: "Linux: Turn On TCP SYN Cookie Protection"

   

I am in the process of setting Apache and PHP for my small business server. I'm not utilizing file upload functionality in any of my PHP scripts. How do I disallow uploading files under CentOS or Ubuntu Linux based LAMP server?

Read answer to: "Apache / Nginx / Lighttpd: PHP Disable File Upload"

   

How do I use rsync command to sync files to a remote host called web-42.vps running VSFTPD ftp server? Can you give me rsync ftp example for Unix like operating systems?

Read answer to: "Linux / Unix: Use rsync Command Over FTP"

   

I run a BT client and few other server program on Linux. Sometime these programs get overloaded with too many connections and crashes. If I restart my apps, I see lots of old IPs in a TIME_WAIT state. How do I force and and close everything in a TIME_WAIT state under Linux operating systems?

Read answer to: "Linux: Force Close A Socket / Port On Server In a TIME_WAIT State"

   

AppArmor is a Linux Security Module (LSM) implementation of name-based mandatory access controls (MAC). How do I start / stop / restart AppArmor under Ubuntu Linux or OpenSuse / Suse Enterprise Linux server systems running on IBM hardware?

Read answer to: "Linux: Start / Stop / Restart Apparmor"

   

I'm setting up server on an Amazon EC2 compute instance powered by Suse Enterprise Linux server. I am using the following command to login into the my EC2 compute from OS X/Ubuntu desktop: ssh -i suse-ec2-server-jp.pem root@ec2-xx-yy-zzz-yyy.compute-1.amazonaws.comI am getting the following error: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: UNPROTECTED PRIVATE KEY FILE! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Permissions 0440 for 'suse-ec2-server-jp.pem' are too open. It is recommended that your private key files are NOT accessible by others. This private key will be ignored. bad permissions: ignore key: suse-ec2-server-jp.pem Password: How do I fix this problem and login using ssh command?

Read answer to: "SSH: WARNING: UNPROTECTED PRIVATE KEY FILE! Error and Solution"

   

I am working on a shell script. I need to find out the current working directory. How do I get the current working directory under Bash or Ksh shell running on Linux or Unix like operating systems?

Read answer to: "Linux / Unix Shell Script: Get The Current Directory"

   

How do I remove the tom user under FreeBSD operating system using command line options?

Read answer to: "FreeBSD: Delete User Account Command"

   

I know how to optimize and compress png images using optipng command. line tool. I have lots of images in JPEG format. How do I compress and optimize JPEG images on my amazon cloud account so that I can save bandwidth on cloudfront cdn account? How do I use an image compressor to create lossless compression on JPEG files, with no effect on image quality in bulk using Linux?

Read answer to: "Linux: Jpeg Image Optimization / Compress Command"

   

A simple shell script wrapper to start / stop / restart NFSv4 service on CentOS / RHEL v.6.x server in a particular order. This script also demonstrates how to use the ln command to create soft links to the same script and take a different action as per $0.

You can dump Linux or Unix server memory. This is useful for forensics analysis, and testing your own system. This is often desirable to see:

• What code and what data actually resides in memory.
• You can search for specific pids memory.
• Search memory for string and other data such as passwords.
• Works as add-on tool for gdb and others.
• Search/replace/dump memory from running processes and core files.
• All kinds of deep hacking activities that simply saves your time and solve problems.

Read more: "Top 8 Tools To Search Memory Under Linux / Unix [ Forensics Analysis ]"

   

I have a large number of files stored in ~/Downloads/ directory. How do I sort and print sizes in human readable format using du -h command under Ubuntu Linux LTS version 12.04 or any other Linux distributions?

Read answer to: "Linux: Sort du -h (human-readable) Output By Size"

   

I would like to use argparse module for Python 2.6 under Debian Linux. However, the code is not working. How do I install and use argparse Python module under Debian Linux 6.x for Python version 2.5 or 2.6?

Read answer to: "Debian Linux Squeeze 6.0: Install Python v2.6/2.5 Argparse Module"

   

I have recently started to managing FreeBSD server along with Ubuntu Linux. However, sudo command, always shows me the following error:

zsh: command not found: sudo

How do I solve this problem and use sudo under FreeBSD 9.x system?

Read answer to: "FreeBSD: Install sudo Command To Execute A Command As The Root"

   

I know how to display line numbers using vim text editor. How do display line numbers in the left side for any text file under Unix or Linux operating systems?

Read answer to: "Linux / Unix: Add Line Numbers To Files"

   

Builtin commands are contained within the bash shell itself. How do I list all bash builtin commands under Linux / Apple OS X / *BSD / Unix like operating systems without reading large bash man page?

Read answer to: "Linux / Unix Bash Shell List All Builtin Commands"

   

I am a new Linux command line user. How do I start or run command in the background so that I can access command prompt immediately?

Read answer to: "Linux: Start Command In Background"

   

I have Debian / Ubuntu Linux. I need to compile software written in C. The gcc throwing an error that read as follows:

gnu/stubs-32.h: No such file or directory compilation terminated. make: *** [foo.o] Error 1

How do I fix this problem under Debian or Ubuntu Linux 64 bit system and compile apps using gcc compiler?

Read answer to: "GCC: Linux gnu/stubs-32.h: No such file or directory"

   

I am a new Python programming user. I am working on user-friendly command-line interfaces, and I want to pass input via the shell args as follows: ./myscript.py filename ./myscript.py in.file output.file ./myscript.py -i in.file -o output.file How do I pass and parse command-line options and arguments using Python under Unix like operating systems?

Read answer to: "Python Command Line Arguments Examples"

   

Kali Linux is the successor of the BackTrack Penetration Testing Linux distribution has been released. From the official project page:

Kali is a complete re-build of BackTrack Linux, adhering completely to Debian development standards. All-new infrastructure has been put in place, all tools were reviewed and packaged, and we use Git for our VCS.

Read more: "Download of the day: Kali Linux ( BackTrack Linux )"

   

I know how to find out battery life status using Linux operating system. How do I monitor battery status on a laptop running FreeBSD version 9.x?

Read answer to: "FreeBSD Laptop: Find Out Battery Life Status Command"

   

How do I use bash auto complete features with various command on CentOS / RHEL / Fedora / Scientific Linux based systems?

Read answer to: "RHEL / CentOS: Install and Activate Bash Autocomplete Feature"

   

The nicstat command is top like utility for network interface card (NIC). It displays information and statistics about all your network card such as packets, kilobytes per second, average packet sizes and more. It works under Solaris and Linux operating systems.

In this post, I will explain how to install and use the nicstat command to find out stats about your NICs under Debian / Ubuntu / RHEL / CentOS Linux operating systems.

Read more: "Solaris / Linux: nicstat Command Show Network Interface Card Statistics"

   

I have a man page stored in my home directory called ~/foo.1. How do I read a $HOME/foo.1 man page file? How can I read the file called ~/foo.1 as a manpage with man command?

Read answer to: "Linux / Unix: Read a Man Page From Local Directory"

   

When I type find . -type d -name "foo" command I get Permission denied error messages. How do I exclude all "permission denied: messages from the find command under Linux or Unix like operating systems?

Read answer to: "Linux / Unix Find Command: Avoid Permission Denied Messages"

   

I upgraded my system to RHEL/CentOS v6.4 and I am getting the following error for 3rd party packages such as Shorewall and fail2ban:

Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from read access on the file . For complete SELinux messages. run sealert -l dea027a2-81dd-4394-96d4-f0d1160c9307 Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from create access on the rawip_socket . For complete SELinux messages. run sealert -l 08757ff1-a08d-4c06-a08b-ff5d53712305 Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from read access on the file . For complete SELinux messages. run sealert -l dea027a2-81dd-4394-96d4-f0d1160c9307 Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from create access on the rawip_socket . For complete SELinux messages. run sealert -l 08757ff1-a08d-4c06-a08b-ff5d53712305 Mar 10 03:43:56 b2 setroubleshoot: SELinux is preventing /sbin/iptables-multi-1.4.7 from read access on the file . For complete SELinux messages. run sealert -l dea027a2-81dd-4394-96d4-f0d1160c9307

How do I fix this problem?

Read answer to: "RHEL / CentOS: SELinux Is Preventing /sbin/iptables-multi-1.4.7 From Read Access On The File/rawip_socket"

   

How do I use the pwd command in Linux or Unix like operating systems? How can I use pwd command in UNIX or Linux shell scripts for automation purpose?

Read answer to: "HowTo: Use pwd Command In Linux / UNIX"

   

I have Red Hat Enterprise Linux 6.x server. How do I find out and groups network bandwidth usage by process under Linux operating systems? How do I find out what programs are using network bandwidth under Linux operating systems?

Read answer to: "Linux: See Bandwidth Usage Per Process With Nethogs Tool"

   

I recently updated my Mozilla Firefox. Firefox now includes a built-in PDF viewer that allows me to see PDF files found on the web without a plugin. The built-in PDF viewer is enabled by default. However, I found that this pdf viewer is not working properly with various web-sites, and it works slowly. How do disable the built-in PDF viewer so that I can use the Adobe PDF viewer or other PDF viewer that is shipped with my operating systems?

Read answer to: "HowTo: Firefox Disable Default PDF Viewer / Plugin"

   

I usually use GIMP (the "GNU Image Manipulation Program") for editing photos, changing colors, resizing photos, applying significant effects and more. It is a free software alternative to Adobe Photoshop. It is also quite popular with graphics artists and webmasters who wants to edit digital images. GIMP is not just a Linux specific program. It works on all leading operating systems, i.e., Mac OS X, MS-Windows and Unix variants. However, like many other powerful open source software, GIMP can be difficult to master. There are many options and plugins. So if, you are looking to learn or master the GIMP program, give The Book of GIMP a try.

Read more: "Book Review: The Book Of Gimp"