Unix Tagged Q & A

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?


I have MySQL database system running on FreeBSD. The server has multiple ip address. The mysqld used by many websites hosted on two other CentOS based servers. I would like to bind MySQL sever running on Unix / Linux server to more than one IP address such as,, and How can I bind mysqld to multiple ips?


I need to replace special characters with equivalent hexadecimal unicode under Linux or Unix like operating system. How do I list or find out unicodes for given characters?


I need to transfer a file called ‘some cool movie.avi’ that contains whitespace under rsync. How do I escape a filename or directory name with spaces in them while using rsync command under Linux / *BSD / Unix like operating systems? How do I use rsync when files / dirs contain spaces?

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I am new to Linux sysadmin work. I am using vi / vim text editor to edit files located in /etc/ directory. I open files using

vi /etc/resolv.conf /etc/hosts

I can edit the /etc/resolv.conf file only. How do I switch between the two open files while using vim text editor under Linux / BSD / Apple OS X / Unix like operating systems?


I have a sample data file:

This is a test.
Unix is Best.
No Linux is the Best.
Space in simple understanding is an area or volume.
Outer space .

I need the output:

Unix is Best.
Outer space .

How do I print all lines that have three (3) words only?


How do I use the rsync tool to copy only the hidden files and directory (such as ~/.ssh/, ~/.foo, and so on) from /home/jobs directory to the /mnt/usb directory under Unix like operating system?