FAQ – nixCraft

CentOS / RHEL 6: Install Midnight Commander File Manager

December 31, 2013December 31, 2013in FAQ last updated December 31, 2013

I am a new CentOS Linux user. How do I install GNU mc (Midnight Commander) on Red Hat Enterprise Linux or CentOS Linux server version 5.x/6.x using bash command line?

Awk Floating Point Number Addition Results Are Unexpected

July 29, 2013in BASH Shell, FAQ, Linux, UNIX last updated July 29, 2013

I am using awk to grep ‘foo’ from a text file and cacluate sum of field # 7. But, result is rounded to an integer. I need exact result such as 385858.66 and not 385858 using the following command:

grep ‘foo’ 2012-2013.txt | awk ‘BEGIN{ sum=0.0}{ sub(“,”,””,$7); sum +=$7}END{ print “$” sum}’
$682444

I want $682444.57 as output. How can I force “awk” to do floating point math?

Awk Find And Replace Fields Values

November 26, 2012in BASH Shell, FAQ, Linux, UNIX last updated November 26, 2012

I have a data as follows :

foo bar 12,300.50 foo bar 2,300.50 abc xyz 1,22,300.50

How do I replace all , from 3rd field using awk and pass output to bc -l in the following format to get sum of all numbers:
12300.50+2300.50+1,22,300.50

Linux / Unix: curl Command Pass Host Headers

October 31, 2012November 7, 2012in BASH Shell, FAQ, UNIX last updated November 7, 2012

How do I send a header to my Web server (such as Nginx / Lighttpd / Apache / ISS) on a Apple OS X or Unix or Linux based system using a curl command line option for testing and debugging my web apps or server nodes behind a load balancer?

wget Command: Download Compressed File By Sending gzip Headers

October 28, 2012October 28, 2012in BASH Shell, FAQ, UNIX last updated October 28, 2012

I have turned on gzip compression as modern web browser supports and accepts compressed data transfer. However, I’m unable to do so with the wget command. How do I force wget to download file using gzip encoding?

Linux AWS: Find And Delete All Files Securely So That No One Can Recover It Ever

October 25, 2012November 4, 2012in Amazon Cloud Computing, CentOS, FAQ, RedHat and Friends last updated November 4, 2012

I‘m currently using Amazon EBS block level storage volumes for use with Amazon EC2 instances powered by Red Hat Enterprise Linux. This volume stores critical webapp and user data. We are moving out to another cloud provider. How do I find files such as *.logs, *.php, *.gz and few other file patterns and securely delete them so that no one can recover it ever?

Linux / Unix: Find Out DNS Server IP Address / Names

October 3, 2012October 3, 2012in FAQ, Linux, UNIX last updated October 3, 2012

How do I find out my DNS server IP address assiged my my ISP under Unix or Linux operating system using command prompt? How do I find preferred dns server under Debian / Ubuntu / Fedora Linux desktop system?