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UNIX

Connect To Amazon AWS EC2 Instance From a CentOS / RHEL Using SSH Client

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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MySQL/MariaDB Server: Bind To Multiple IP Address

I have MySQL/MariaDB database system running on a FreeBSD/Linux server. The server has multiple ip address. The mysqld used by many websites hosted on two other CentOS Linux based servers. I would like to bind MySQL sever running on a Linux or Unix-like server to more than one IP address such as 202.54.1.2, 202.54.1.10, and 202.54.1.15. How can I bind mysqld to multiple ips?
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Linux / Unix: Unicode and HTML Characters Lookup By Name or Number

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?
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Linux / Unix: Rsync Copy Files & Directories Names With WhiteSpaces and Blanks

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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Linux / Unix vi / vim: Open and Switch Between Multiple Files

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?
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Linux / Unix: Sed / Grep / Awk Print Lines If It Got 3 Words Only

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?
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Linux / Unix: Rsync Copy Hidden Dot Files and Directories 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?
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Bash Check If Shell Is Interactive or Not Under Linux / Unix Oses

How do I check in GNU/Bash if a shell is running in interactive mode or not while writing shell scripts?
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Grep Include Only *.txt File Pattern When Running Recursive Mode

I‘m using Debian Linux as my development workstation. I would like to search a directory called ~/projects/ recursively for “foo” word only for *.txt files. How do I search all text files in ~/projects/ for “foo” word using grep command?
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HowTo: Use Grep Command In Unix / Linux To Search Subdirectories

I would like to search and find all files which contain a word called “main()” for all directories located in $HOME/project/school. How do I use the grep command to find text including all subdirs under Unix or Linux operating systems?
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