Frequently Asked Questions About Linux / UNIX

Ubuntu Linux: Turn On Exec-Shield Buffer Overflow Protection

nixCraft — Sun, 19 May 2013 18:13:14 +0000

I am trying to set exec-shield protection on Linux as described here but getting the following error on Ubuntu Linux server version 12.04 LTS:

sysctl -w kernel.exec-shield=1 error: "kernel.exec-shield" is an unknown key

How do I fix this problem and make sure exec-shield buffer overflow protection security feature turned on Ubuntu Linux?

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Ubuntu Linux: Install vim Text Editor

nixCraft — Sun, 19 May 2013 17:28:30 +0000

I recently switched from OS X to Ubuntu. When I run the 'vim file.c' command at terminal, I see an error message that read as follows:

The program 'vim' can be found in the following packages: * vim * vim-gnome
* vim-tiny * vim-athena * vim-gtk * vim-nox Try: apt-get install <selected package>

How do I fix this problem and why vim is not a default text editor on Ubuntu Linux? How can I install full-fledged vim text editor in Ubuntu Linux?

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Nginx: SPDY SSL Installation and Configuration On Debian / Ubuntu

nixCraft — Sun, 19 May 2013 15:24:36 +0000

Google Chrome/Chromium, Firefox and Opera browser support SPDY networking protocol. It enables faster browsing on supported sites. SPDY is similar to HTTP, with particular goals to reduce web page load latency and improve web security. SPDY achieves reduced latency through compression, multiplexing, and prioritization. How do I enable nginx SPDY support running on Debian or Ubuntu Linux server?

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RHEL / Fedora /CentOS Linux: Set RPM Build Environment

nixCraft — Sun, 19 May 2013 09:19:52 +0000

How do I set an rpm build environment on CentOS / RHEL / Red Hat Enterprise Linux version 6.x? How can I set rpm build environment on latest version of Fedora Linux?

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Ubuntu / Debian Linux: Install gcutil Tool To Manage Google Compute Engine

nixCraft — Sun, 19 May 2013 06:04:43 +0000

How do I install and use gcutil - a command-line tool that is used to manage Google Compute Engine resources under Debian or Ubuntu or CentOS/Fedora Linux desktop operating systems?

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Linux / Unix: View Overlapping Man Page With Same Names

nixCraft — Thu, 16 May 2013 19:06:02 +0000

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?

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OpenBSD: Mount An ISO Image Command

nixCraft — Thu, 16 May 2013 18:42:21 +0000

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

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Ubuntu Linux: Install Latest Oracle Java 7

nixCraft — Thu, 16 May 2013 16:35:38 +0000

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+?

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Linux: Dell Laptop Fan Control And Get CPU Temperature

nixCraft — Thu, 16 May 2013 09:12:04 +0000

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?

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scp: Do not Overwrite Existing File On Linux or Unix System

nixCraft — Fri, 10 May 2013 20:03:49 +0000

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?

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Ubuntu Linux: Install Google Chrome Browser Command

nixCraft — Fri, 10 May 2013 18:03:36 +0000

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?

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Ubuntu Linux: Install Wake On Lan Client For Server

nixCraft — Fri, 10 May 2013 10:14:05 +0000

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

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

nixCraft — Sun, 05 May 2013 19:06:53 +0000

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?

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Linux / Unix: Find All Hidden Dot Directories and Delete

nixCraft — Sun, 05 May 2013 18:27:16 +0000

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.

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Linux WARNING: Duplicate VG name server1 LVM2 Error and Solution

nixCraft — Sun, 05 May 2013 17:55:14 +0000

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?

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

nixCraft — Sun, 05 May 2013 05:53:32 +0000

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?

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Debian / Ubuntu: Set Port Knocking With Knockd and Iptables

nixCraft — Wed, 01 May 2013 18:51:33 +0000

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?

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Debian / Ubuntu: Install gem The FrontEnd To Rubygems

nixCraft — Wed, 01 May 2013 16:55:18 +0000

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

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Vi / Vim: Wipe and Undo All Changes Since Opening a File

nixCraft — Sun, 28 Apr 2013 20:11:25 +0000

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?

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Apache 2: Reload HTTPD Configuration File Without Restarting Apache Config Changes

nixCraft — Sun, 28 Apr 2013 03:47:32 +0000

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?

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