eGuys

Bash Shortcuts

2014-10-19T08:48:00.000-07:00

Command Editing Shortcuts
Ctrl + a - go to the start of the command line
Ctrl + e - go to the end of the command line
Ctrl + k - delete from cursor to the end of the command line
Ctrl + u - delete from cursor to the start of the command line
Ctrl + w - delete from cursor to start of word (i.e. delete backwards one word)
Ctrl + y - paste word or text that was cut using one of the deletion shortcuts (such as the one above) after the cursor
Ctrl + xx - move between start of command line and current cursor position (and back again)
Alt + b - move backward one word (or go to start of word the cursor is currently on)
Alt + f - move forward one word (or go to end of word the cursor is currently on)
Alt + d - delete to end of word starting at cursor (whole word if cursor is at the beginning of word)
Alt + c - capitalize to end of word starting at cursor (whole word if cursor is at the beginning of word)
Alt + u - make uppercase from cursor to end of word
Alt + l - make lowercase from cursor to end of word
Alt + t - swap current word with previous
Ctrl + f - move forward one character
Ctrl + b - move backward one character
Ctrl + d - delete character under the cursor
Ctrl + h - delete character before the cursor
Ctrl + t - swap character under cursor with the previous one

Command Recall Shortcuts
Ctrl + r - search the history backwards
Ctrl + g - escape from history searching mode
Ctrl + p - previous command in history (i.e. walk back through the command history)
Ctrl + n - next command in history (i.e. walk forward through the command history)
Alt + . - use the last word of the previous command

Command Control Shortcuts
Ctrl + l - clear the screen
Ctrl + s - stops the output to the screen (for long running verbose command)
Ctrl + q - allow output to the screen (if previously stopped using command above)
Ctrl + c - terminate the command
Ctrl + z - suspend/stop the command

Jenkins is hanging.

2014-05-17T09:17:00.000-07:00

I am running master-slave model with windows and linux slaves. Occasionally jobs are getting struck and Jenkins was not able to execute any further build.

The typical scenario is as follows

A job hangs.*
The node becomes unusable. A job starting on the node stops at "Building remotely on MySlave".
GIT polling gets stuck.
Polling only resumes after a Hudson restart.

The issue does not seem to be specific to one SCM, we are using Hg, SVN and GIT. This problem become even worse, the only way to unlock blocking is to restart the jenkins service for every three hours. I checked memory details and it looks fine but observed git zombie process. More zombie process with more uptime. We were rebooting the server to clear these process.

http://www.jenkins.com/threaddump

There are more SCM polling activities scheduled than handled, so the threads are not keeping up with the demands. It is observed that there are more SCM polling happening every hour that to first minute of the hour 0 * * * * .

Solution is change SCM polling from happening all at once i.e., 0 * * * * to be more spread out over the course of an hour @hourly or H * * * * .
Did a find and replace. Problem is resolved.

If job relies on hooks from scm to trigger builds, then disabling polling in your job altogether is recommended.

In order for the SCM hook to work, the ‘Poll SCM’ checkbox needs to be checked in the Jenkins job configuration. However, it’s ok to leave the ‘schedule’ field blank. This way no polling will happen, and SCM will be able to trigger Jenkins builds with the Jenkins hook.

How to set environment variable for everyone under RHEL system

2014-04-15T07:55:00.000-07:00

In Ubuntu it is just adding key value pairs in /etc/environment,
Where as in RHEL create a script under /etc/profile.d/

In below example I am trying to add Maven home environment variable and adding the installation to the path.

cat /etc/profile.d/mvn.sh
#Add Maven installation to the path
export M2_HOME=/opt/jenkins/tools/hudson.tasks.Maven_MavenInstallation/default
export M2=$M2_HOME/bin
export PATH=$M2:$PATH

Reboot your computer,
Verify $echo $M2_HOME
/opt/jenkins/tools/hudson.tasks.Maven_MavenInstallation/default

That is all.

On boot up all the .sh files under /etc/profile.d/ will be sourced, so this will effect for all users.

If you know any easier way than this please let me know.
Thank you

JDK for RHEL family

2014-02-22T08:32:00.000-08:00

Download the required Sun JDK rpm from Sun.

wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/7u60-b19/jdk-7u60-linux-x64.rpm"

Once installation completed then normal, use yum

yum install jdk-7u60-linux-x64.rpm

How to change default route on Linux box

2012-12-13T00:15:00.003-08:00

In computing, route is a command used to view and manipulate the TCP/IP routing table in both Unix-like and Microsoft Windows operating systems. Manual manipulation of the routing table is characteristic of static routing.

In Linux distributions based on 2.2.x Linux kernels, the ifconfig and route commands are operated together to connect a computer to a network, and to define routes between computer networks. Distributions based on later kernels have deprecated ifconfig and route, replacing them with iproute2, which adds functions such as policy routing and traffic shaping.

route (or) route -n

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         10.50.32.1      0.0.0.0                UG    0        0        0 wlan0
10.50.32.0         *               255.255.240.0     U      9        0        0 wlan0
link-local          *               255.255.0.0       U     1000   0        0 eth0
192.168.195.0   *               255.255.255.128 U     1     0        0 eth0

You can use -n option, to display numerical addresses instead of trying to determine symbolic host names (via dns or /etc/hosts file). This is useful if you are trying to determine why the route to your nameserver has vanished.
To delete current default route
                          sudo route del default
To add default gateway
                          sudo route add default gw 192.168.195.1 eth0
More on route command

[How to] Auto mount Windows NTFS drives with executable permissions

2012-05-01T03:10:00.000-07:00

Step 1:
Open terminal, type sudo blkid -c /dev/null
This will list all the partitions
/dev/sda1: UUID="052206fd-a307-4ff3-8aa5-fd8999a3c433" TYPE="ext4"
/dev/sda2: LABEL="D" UUID="78AC06E3AC069BAE" TYPE="ntfs"
/dev/sda4: LABEL="E" UUID="3941CE1615244BEB" TYPE="ntfs"
In my system it lists below three partitions,

sda1 is ext4 type (Linux OS drive mounted to root /)
sda2 ntfs type(Windows drive, This drive is has label 'D')
sda3 ntfs type(Windows drive, This drive is has label 'E')

Step 2:
You need to know your user id (UID) and your group id(GID), for that in terminal type
echo $UID
GID will be same as your UID. However you can confirm your GID by typing the command cat /etc/group
In most cases both UID and GID will be 1000

Step 3:
List of partitions which need to mount on boot up will be stored in /etc/fstab file.
In terminal, type sudo geany /etc/fstab
(Use any of your favorite text editor, I used Geany.)

Hello there. If you're reading this then you're probably trying to get around the fact that NTFS partitions don't support Linux file permissions. This tutorial will, hopefully, show you how to get around this little problem. Fortunately for you, this only involves editing a single file. Easy, eh?

The file in question is located at /etc/fstab. This file contains a list of partitions which you want mounted, one partition per line. Now, if you take a look at this file, you'll see that there are several lines already. DO NOT EDIT THESE LINES. They are important. Editing them, even slightly, may cause your system to stop booting.

If you take a look at this file, you'll see that there are several columns of information. Assuming that you haven't already created one, you'll need to add a new line for your NTFS partition. To know what to put as the information for the partition, we'll need to know a few things about it. Once you have all the information, you can edit fstab by running

Code:

gksu gedit /etc/fstab

Firstly: which partition is it?
In this case, this needs to be a device node identifier. e.g. /dev/sda1, a partition UUID, or a partition label. Running
Code:
```
sudo blkid -c /dev/null
```
in a terminal will tell you all the relevant information about your partitions. Hopefully you can determine from this list which one is the correct partition.

If you use a UUID or Label, you need to declare it as such. e.g. "LABEL=Windows", "UUID=ABCDEFGHIJKLKLMNOP".
Next, where should it be mounted?
This part is simple: where do you want the partition to be accessible from? Ubuntu mounts partitions in /media by default, so if you want the partition to be mounted there, say so. e.g. "/media/Windows". You will need to manually create this folder since fstab will complain if it's not there, so make sure that the folder isn't being used already, and run
Code:
```
sudo mkdir /media/Windows
```
Next, which filesystem should it be mounted as?
Since we're mounting an ntfs partition, specify "ntfs-3g" for this column. Don't use "ntfs" unless you don't want to be able to write to the partition after it's mounted (by write, I mean making new files, editing files, moving files and folders, etc.; the "ntfs" driver is outdated and only lets you read files.)
Next, what options should it be mounted with?
This is the most important column in this case, this is where you specify permissions. How you do this isn't immediately obvious, but there's a way, and it's actually rather simple.

This is a comma separated list, so don't use spaces or tabs, or else you'll find that the mount line doesn't work as expected. To specify the permissions, you merely need to declare three things: UID, GID, and umask.
- uid=#### specifies which userid should own the files on the partition. e.g. "uid=1000" means that the user with the id "1000" should own the files. You can find out your UID by opening a terminal and running "echo $UID".
- gid=#### specified which groupid should own the files on the partition. e.g. "gid=1000" means that the group with the id "1000" should own the files. Finding out groupids is slightly more difficult than finding out your userid because you can belong to several groups at the same time. Now, Ubuntu normally creates a group for every user, with the same ID as the UID, so you can probably use your UID as the GID. However, you can get a list of groups by running, in a terminal, "cat /etc/group". This will display a list with upto four colon-separated fields per line. The lines will contain the following items: name, an encrypted password, the GID, and a list of users in the group. Find the group you want to use, and add it's GID to the options.
- umask=UGO is the most important of the three options; it specifies what the permissions will be for the user, the group, and everyone else. The numbers used here need to be between 0 and 7, anything else will probably cause an error. These numbers are actually an inverse of normal permissions, so while "7" means "read, write, and execute" in normal permission setting, in fstab "7" means "no permissions". Setting "umask=000" will give EVERYONE read, write, and execute permissions. For clarification, the U is the permissions for the user, G is for group, and O is for others. See this for more details about umask.
You may also add other things to this list. Generally speaking, it's best to start with the "defaults" option. "auto" makes the partition mount automatically when you boot up. Read more here: http://www.tuxfiles.org/linuxhelp/fstab.html
The final two columns should be "0" and "0".
These two columns are only used for Linux filesystems, so setting them to 0 stops any complications from arising.

A finished fstab line may look like:

Code:

UUID=ABCDEFGHIJKLKLMNOP /media/Windows ntfs-3g defaults,auto,uid=1000,gid=1000,umask=002 0 0

another example:

Code:

/dev/sdb5 /mnt/Music ntfs-3g defaults,uid=1002,gid=1500,umask=227 0 0

The next time you boot up, or the next time you run "sudo mount -a", the partition should be mounted where you want it, with the permissions you want it to have.

Mount Windows NTFS drives with executable permissions on Linux machine.

The scripts present in NTFS dri

#!/bin/bash
sudo umount /media/D/
sudo mkdir /media/D/
sudo fdisk -l
sudo mount.ntfs-3g /dev/sda2 /media/D/

Linux best/must to have applications

2012-04-30T11:58:00.000-07:00

VLC media player

VLC is a free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVD, Audio CD, VCD, and various streaming protocols.
This should be the default for Linux instead of any other.
Plays almost everything, there won't be any format that VLC can not play.

sudo apt-get install vlc

Synaptic package manager

Synaptic is a graphical package management tool based on GTK+ and APT. Synaptic enables you to install, upgrade and remove software packages in a user friendly way.
Besides these basic functions the following features are provided:

Search and filter the list of available packages
Perform smart system upgrades
Fix broken package dependencies
Edit the list of used repositories (sources.list)
Download the latest change log of a package
Configure packages through the debconf system
Browse all available documentation related to a package (dwww is required)

sudo apt-get install synaptic

GParted Partition Editor

GParted is a free partition editor for graphically managing your disk partitions.
With GParted you can resize, copy, and move partitions without data loss, enabling you to:

Grow or shrink your C: drive
Create space for new operating systems
Attempt data rescue from lost partitions

sudo apt-get install gparted

Pidgin Internet Messenger

IM all your friends in one place
Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once.
Supported chat networks:
AIM Bonjour Gadu-Gadu Google Talk Groupwise ICQ IRC MSN MXit MySpaceIM SILC SIMPLE Sametime XMPP Yahoo! Zephyr

sudo apt-get install pidgin

Geany: Replacement for Notepad++ in Linux

Geany is a text editor using the GTK2 toolkit with basic features of an integrated development environment. It was developed to provide a small and fast IDE, which has only a few dependencies from other packages. It supports many filetypes and has some nice features.

I replaced my default text editor with Geany and I am happily working with it.

sudo apt-get install geany

Wine (Wine Is Not an Emulator)

Wine is a free and open source software application that aims to allow computer programs written for Microsoft Windows to run on Unix-like operating systems. Wine also provides a software library, known as Winelib, against which developers can compile Windows applications to help port them to Unix-like systems.

Add the WineHQ PPA Repository: sudo add-apt-repository ppa:ubuntu-wine/ppa

sudo apt-get install wine

Geany: Replacement for Notepad++ in Linux

2012-04-30T03:20:00.001-07:00

I audited to Notepad++ in Windows, and was searching for its replacement in Linux for long time. My search ends when I came to know about Geany.
Geany has almost all the features that Notepad++ has.
Geany is little slow when searching in files, when compared to Notepad++, but it is hardly noticeable.

I replaced my default text editor with Geany and I am happily working with it.

To install Geany: sudo apt-get install geany

Below is a brief introduction for Geany.
Geany is a small and lightweight Integrated Development Environment. It was developed to provide a small and fast IDE, which has only a few dependencies from other packages. Another goal was to be as independent as possible from a special Desktop Environment like KDE or GNOME - Geany only requires the GTK2 runtime libraries.

Some basic features of Geany:

Syntax highlighting
Code folding
Symbol name auto-completion
Construct completion/snippets
Auto-closing of XML and HTML tags
Call tips
Many supported filetypes including C, Java, PHP, HTML, Python, Perl, Pascal (full list)
Symbol lists
Code navigation
Build system to compile and execute your code
Simple project management
Plugin interface (see Plugins)

Geany is known to run under Linux, FreeBSD, NetBSD, OpenBSD, MacOS X, AIX v5.3, Solaris Express and Windows. More generally, it should run on every platform, which is supported by the GTK libraries. Only the Windows port of Geany is missing some features.

The code is licensed under the terms of the GNU General Public Licence.

System-wide environment variables

2012-04-30T03:06:00.000-07:00

System-wide environment variables

Environment variable settings that affect the system as a whole (rather then just a particular user) should not be placed in any of the many system-level scripts that get executed when the system or the desktop session are loaded, but into

/etc/environment - This file is specifically meant for system-wide environment variable settings. It is not a script file, but rather consists of assignment expressions, one per line. Specifically, this file stores the system-wide locale and path settings.

ex: sudo geany /etc/environment

or sudo gedit /etc/environment

geany is my text editor.

You can use gedit

Not recommended:

/etc/profile - This file gets executed whenever a bash login shell is entered (e.g. when logging in from the console or over ssh), as well as by the DisplayManager when the desktop session loads. This is probably the file you will get referred to when asking veteran UNIX system administrators about environment variables. In Ubuntu, however, this file does little more then invoke the /etc/bash.bashrc file.
/etc/bash.bashrc - This is the system-wide version of the ~/.bashrc file. Ubuntu is configured by default to execute this file whenever a user enters a shell or the desktop environment.

Note: When dealing with end-user/home desktop systems may be appropriate to place settings in the user's ~/.pam_environment files discussed above rather then the system-wide ones, since those files do not require one to utilize root privileges in order to edit and are easily moved between systems.

Arrays in Shell script

2012-04-25T22:18:00.003-07:00

Given the array defined by the following code:

names=( Jennifer Tonya Anna Sadie Molly Millie)

The individual elements in the array can be accessed by their numeric index (remember that they start counting a zero) with:

${names[0]}  -> Jennifer
${names[3])  -> Sadie

All of the elements can be accessed at the same time (which is useful in a for loop) with the following:

${names[@]}
${names[*]}

The number of elements in the array can be obtained with:

${#names[@]} -> 6

A range of elements can easily be specified with the following syntax:

${names[@]:2:3}  -> Anna Sadie Molly
${names[@]:3}  ->  Sadie Molly Millie

The first example starts at element 2 (the third element) and returns the next three elements (:2:3). The second example starts at record 3 and returns all of the remaining records (:3).

[How to] Pass arguments to functions in Shell script

2012-04-25T21:13:00.001-07:00

#!/bin/bash

fnSum()

{

arg1=$1

arg2=$2

echo `expr $1 + $2`

echo $(($1+$2))

}

#calling function

fnSum 45 12

output:

Comand Line Arguments in Shell and BAT

2012-04-25T02:43:00.002-07:00

script.sh element1 element2

$# -> 2 SIZE
$* -> element1 element2
$0 -> script.sh
$1 -> element1
$2 -> element2

--------------------

batch.bat element1 element2

set argC=0;for %%x in (%*) do Set /A argC+=1; echo %argC%; --2 -->size

%* -> element1 element2
%0 -> batch.bat
%1 -> element1
%2 -> element2

RS232 output

2012-04-03T06:28:00.002-07:00

Commands to see logs from serial cable:

stty -F /dev/ttyUSB0 115200
cat /dev/ttyUSB0

First

2012-04-01T08:10:00.001-07:00

Use GoDaddy's configuration tool to automatically create the necessary Google Apps MX records. Log into the configuration tool at https://www.godaddy.com/gdshop/google/gmail_login.asp.