Category Archives: BASH

VMWare Workstation start on boot CentOS

CentOS 7 VirtualBox Guest Additions Installation

CentOS 7 VirtualBox Guest Additions Installation Tutorial

In the following tutorial, I’ll demonstrate how to install Guest Additions on your VirtualBox hosted CentOS 7 Minimal machine.
Although this tutorial is intended for CentOS 7 minimal, it’s will probably also work on other CentOS releases.

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tr vs sed – String manipulation commands in Linux/Unix

Overview

tr and sed are very powerful stream and character manipulation commands, Each has its own advantage with string manipulation.
tr vs sed - String manipulation commands in Linux/Unix
 

tr vs sed usage and examples

Replace “hi” with “bye”

echo "hi hi" | sed 's/hi/bye/g'
output: bye bye

echo "hi hi" | tr 'hi' 'bye'
output: by by

While sed can replace strings tr can only replace characters,
so with complete string replacement sed is the way to go.
 
Replace “good” with “bad”
echo "good good" | sed 's/good/bad/g'
output: bad bad

echo "good good" | tr 'good' 'bad'
output: bddd bddd

tr is more like a mapping command, it’s like a set of rules:
The char “g=b”, the char “o=a”,”o=d” the last one will be the active one “o=d”.
 
Change ‘ ‘ to a new line:
echo "line1 line2" | tr ' ' '\n'
output:
line1
line1

echo "line1 line2" |sed -e 's/\s\s*/\n/g'
output:
line1
line1

 
As you can see tr is a lot easier for this job.
 
 
Enjoy.

Setup BIND DNS Server on CentOS 7

VMware Tools CentOS 6.x easy installation guide.

VMware Tools CentOS 6.x easy installation guide.

Prerequisities

if you have installed new setup of centos or you haven’t installed yet, you need make, gcc, kernel-devel..

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Linux fg bg commands usage and examples

Overview

Linux fg bg commands usage and examples using CTRL-Z and jobs command.
Move a process between background and foreground modes with paused and running states.

Usage and examples

Pause a process

When running a process you can use CTRL-Z to pause the process and free the current shell instance:
Linux fg bg commands ctrl-z-stop

Linux jobs command

To view the stopped jobs use the jobs command:

jobs

You should receive something like this (Job number, Status, Command):
[1]+  Stopped                 ls --color=auto -l --color=auto -lla -R /

Run a process in the background

You can start a process in the background from the start using an ‘&’ mark at the end of the command:

cp /source /destination &

linux fg bg commands

To move a job to the foreground execution (for example job 1):

fg 1

To move a job to the background execution (for example job 1):
bg 1

Kill paused jobs

To kill a paused job you can use the kill command followed by the job number (for example job 1):

kill %1

Enjoy

Load Balancing SSH Connections using Pen on CentOS Linux

Overview

Load Balancing SSH Connections using Pen, a load balancer for “simple” tcp based protocols such as http or smtp.
It allows several servers to appear as one to the outside and automatically detects servers that are down and distributes clients among the available servers. This gives high availability and scalable performance.

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Load balancing Remote Desktop Services using Pen

Overview

Load balancing Remote Desktop Services using Pen, a load balancer for “simple” tcp based protocols such as http or smtp.
It allows several servers to appear as one to the outside and automatically detects servers that are down and distributes clients among the available servers. This gives high availability and scalable performance.

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Backup Multiple MySQL Databases using a BASH script

Overview

In this tutorial I will give an example to a BASH scripts that will help you backup multiple MySQL databases at once.

Backup Multiple MySQL Databases using a BASH script

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Batch Sort Folders by Size With Linux DU

Overview

Use Linux DU to batch check and sort folder sizes in Linux.
You can also use Linux DU command on a Windows share or a NAS CIFS/NFS share.

Linux DU

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VMware Zimbra Active Directory User Mailbox Sync

Overview

Zimbra Active Directory User Mailbox Sync script uses Zimbra utility to Add or Remove mailboxes according to the AD User List.
You can sync all AD users at once or Create a Security Group And add members in order to assign a mailbox.

VMWare Zimbra Active Directory Sync

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