4 Paisa

Change date in Mac via terminal

2019-07-24T18:59:00.000+05:30

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sudo date MMDDHHmmYY

(Month,date,hour,minute,year)

For e.g., sudo date 0101101019 to change date to 10 hour 10 min of 2019 Jan 01.

Sort unix folders by size

2019-07-21T18:57:00.001+05:30

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du -ks * | sort -n -r

Column selection in Eclipse

2018-07-25T05:16:00.000+05:30

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Eclipse also offers column selection functionality similar to popular text editors Notepad++, Sublime Text2.

On a Mac, need to press "cmd + option + A"
On Windows and Linux, you need to press "alt + shift + A"

Please note doing above will take you to block selection mode, and you need to press same keys again to come back to normal mode.

Source: https://stackoverflow.com/questions/1053725/how-do-i-enable-the-column-selection-mode-in-eclipse

Validate firewall connectivity using nc

2018-07-18T11:44:00.000+05:30

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In absence of telnet we can use nc (which version??) to validate connectivity.

nc -w 2 -v 10.0.0.1 < /dev/null; exitCode=$?; echo "Exit code = $exitCode"; if [ $exitCode -ge 1 ]; then echo "No connectivity"; else echo 'SUCCESS!!!'; fi; >> fw_validation.txt

To setup a simple log monitoring script

2018-07-13T11:43:00.000+05:30

// TODO

#! /bin/bash
echo "monitoring log files"
if grep SQLSTATE application-cronjob-*-`date +"%Y-%m-%d"`.log ;
then
echo "sending mail"
grep -10 SQLSTATE application-cronjob-*-`date +"%Y-%m-%d"`.log | mail -s "errors found in logs for `date +"%Y-%m-%d"` example@example.com
fi

Bash for loop examples

2017-11-01T12:12:00.000+05:30

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For loop example in bash script:
To get yarn log files for multiple spark jobs, we can use this command.
for i in `cat appid.txt`; do echo $i; yarn logs -applicationId $i > sparkjob_01sep_logs/$i.log; echo "——"; done

For loop with sequence and ssh into multiple servers:
To login into multiple servers and run a command, we can use below command.

for i in `seq 101 125`;do ssh -q machinename$i "hostname;ls -ltr";done

Java - redirect standard output stream to file

2017-02-10T10:32:00.000+05:30

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We can redirect all System.out.println output to a file with below code snippet.

System.setOut(new PrintStream(new BufferedOutputStream(new FileOutputStream("/tmp/output.txt"))));

Create a desktop shortcut in Mac with Automator

2017-01-30T02:47:00.000+05:30

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Open Automator
File > New
select Application
Then add "Run Shell Script" option
Give the command to run, here I am giving Google chrome canary with no proxy option

/Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --no-proxy-server=

Then Save with the name you want.

By default this will show automator icon.
Here is how to set your favorite icon.
Right click on Chrome canary icon and select "Get Info"

Then click on the icon and press Cmd+c
to copy the icon.
Now open info window on newly created icon, select the icon in the same place (which shows automator icon) press Cmd+v to paste the previously copied icon.

Change proxy settings only for Chrome

2017-01-30T02:18:00.000+05:30

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Disable proxy setting
Add command line parameter --no-proxy-server= to the command. (In windows, add this to the target path in the shortcut properties)

Specify different proxy
Add command line parameter --proxy-server="127.0.0.1:8080" to the command

Specify no proxy server list
Add command line parameter like this --proxy-bypass-list="127.0.0.1;localhost"

Find out license information of all maven dependencies

2016-02-26T12:06:00.000+05:30

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You want to use a maven dependency and you also need to know about the license information. If it is only one dependency you can easily check it. But each maven dependency more dependencies itself to do its work. That means you have to find out license information of all those jars also.

For example, if you want to use cassandra-unit jar (https://github.com/jsevellec/cassandra-unit) you have to know the license of this jar and 41 other jars also. You see how painful it is. To use one jar you have to find out information of 41 jars, think if you want to use some 10 jars, how many more jars you need to check.

Here maven plugin maven-project-info-reports-plugin comes to the rescue. This plugin can find out all the information you need.

I followed below steps to solve my problem.

Step 1:
I have created a new maven project in the eclipse and added my dependency (cassandra-unit). Then I have added maven-project-info-reports-plugin in the reports section.

Now pom file looks like below.

Step 2:

Then run maven goal mvn project-info-reports:dependencies and it will create a html file at target/site/dependencies.html which gives you all the information you need.

You can see license details of the Maven site plugin

POM.XML

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.reddy</groupId>
    <artifactId>SampleDependencies</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.cassandraunit</groupId>
            <artifactId>cassandra-unit</artifactId>
            <version>2.2.2.1</version>
        </dependency>

    </dependencies>

    <reporting>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-project-info-reports-plugin</artifactId>
                <version>2.6</version>
            </plugin>
        </plugins>
    </reporting>

</project>

Find out which Java thread is causing the high CPU usage

2014-11-03T14:17:00.001+05:30

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You see your java application is consuming high CPU but you don't know specifically which thread is consuming CPU out of thousand threads.

The solution is very simple.
1. First we need to find out native thread ID that is using high CPU. Issue top -H command on terminal and it will show all threads and the percentage of the CPU they are consuming. Find out your application thread from the list and note down native thread id which will be shown in the first column named PID.

2. Take thread dump of your application.

3. Thread dump contains native thread ID but in hexadecimal format. So convert the decimal thread ID we have noted in the first step to hexadecimal value and search for this value in the thread dump and you will find the thread's stack trace.

You can see more detailed explanation in the source link below. It gives an example program and also details how to do this in both Unix and Windows.

----------------------------------------------------------------------------------------------
Source: https://blogs.oracle.com/jiechen/entry/analysis_against_jvm_thread_dump

To get http status code from curl call

2014-05-26T12:03:00.000+05:30

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We can use below command to get http response code of a URL from bash script.

status_code=$(curl --write-out "\n%{http_code}\n" --silent --output /dev/null --insecure https://www.google.co.in/)

silent - to stop progress information in output
output - we are re-directing normal output to null device
write-out - whatever things we needed can be given here. Here we are printing http status code. It will be printed after completion, i.e., after printing all output.
insecure - this allows connections to SSL sites without certs

References: http://stackoverflow.com/a/2220646/324900

Overriding logback file embedded in jar file

2014-05-07T18:27:00.001+05:30

I was trying to run a jar file by setting it up in cronjob. Now this jar file contains a logback configuration file included in it which is causing me problem because all logs are being written to a specific file name, like processnamelogs.log. All runs of jar file will append to the same log file.

Now this is not what I wanted since the log file is going to grow huge in few runs. Also if all runs of jar file are writing to same log file it will be difficult to setup a monitoring script to check for errors.

What I wanted is that each run of jar file writes to a separate log file with its name containing start time of that run. So it will be easy to go through logs in case of errors. Also I can easily setup a monitoring script to only search in the log files with current date in their names.

So I need to write my own logback configuration file and a way to make sure the jar file uses my configuration file instead of embedded one. I have searched and got one system property (logback.configurationFile) which does what I wanted.

e.g.,
java -Xms128m -Xmx512m -XX:MaxPermSize=256m -jar -Dlogback.configurationFile=./mylogback.xml ./process.jar

mylogback.xml

<configuration>

  <!-- Insert the current time formatted as "yyyyMMdd'T'HHmmss" under
       the key "bySecond" into the logger context. This value will be
       available to all subsequent configuration elements. -->
  <timestamp key="bySecond" datePattern="yyyyMMdd'T'HHmmss"/>

  <appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <!-- use the previously created timestamp to create a uniquely
         named log file -->
    <file>log-${bySecond}.txt</file>
    <encoder>
      <pattern>%logger{35} - %msg%n</pattern>
    </encoder>
  </appender>

  <root level="DEBUG">
    <appender-ref ref="FILE" />
  </root>
</configuration>

References:

http://logback.qos.ch/manual/configuration.html#configFileProperty
http://logback.qos.ch/manual/appenders.html#uniquelyNamed

find out number of occurrences of a character in mysql

2014-04-30T14:41:00.000+05:30

How to find out count of a specific character or a char-sequence in mysql?

There is no simple method available to do that. However we can use below method to find out.

select length(x) - length(replace(x, ":", ""))

What is Heartbleed Bug

2014-04-10T23:24:00.000+05:30

It is basically a security bug (buffer overread) which is in the Open SSL implementation which is used by a looooooooot of websites on the internet to secure ( :) ) the communication between browser and website.

Jacob on stackexchange explained this issue in detail. Read his answer at superuser.com

to view only directories in Unix

2014-01-26T20:38:00.000+05:30

If you have ever wanted to show a list of subdirectories underneath the current directory while at the terminal prompt, there’s a simple command that can help.
Simply run the following command from the bash terminal prompt, which filters the file listing to only show folders:

ls -l | grep ^d

Since typing that whole command every time you want to show a list of directories might get a little tiring, you can use the alias feature to assign it to something you can more easily remember:

alias lsd="ls -l | grep ^d"

Now when you type “lsd” at the prompt, you will see a list containing only the directories, which can be very useful when you are trying to navigate through a messy set of folders.

Some useful VI editor commands

2014-01-19T20:36:00.000+05:30

J – to join two lines
Deletion
dl – single character, dw – Single word, dd – single line, d$ – to the end of the line
Editing
i – insert mode, A – append to the end of the line, o – insert in next line
Misc
:set list – to see special characters
:%s/str1/str2/g – search and replace

Some useful variables in Unix

2014-01-12T20:35:00.000+05:30

$$ = The PID number of the process executing the shell.
$? = Exit status variable.
$0 = The name of the command you used to call a program.
$1 = The first argument on the command line.
$2 = The second argument on the command line.
$n = The nth argument on the command line.
$* = All the arguments on the command line.
$# The number of command line arguments.

Read password from shell script

2014-01-05T20:29:00.000+05:30

Since you don't want password to be not displayed on terminal you need to disable echo before reading password. Once password is read you need to enable it again.

#————————————————————
# Read Password
#————————————————————
/usr/ucb/echo -n “Please Enter Password For User ${SUSER}: “
stty -echo
read SPSWD
stty echo
clear

How to do MySQL port forwarding using PuTTY

2011-12-02T12:34:00.000+05:30

1. Go to Session: enter site name, port, etc…
2. Window > Behaviour : Window Title can be set here.
3. Connection > Data: User name should be given Auto-login username.
4. Connection > SSH : check Enable Compression.
5. Connection > SSH > Tunnels: enter local port number in Source Port, the port to be forwarded in Destination in the form : and click on Add to create the tunnel.
For MySQL client, this local port will be the port and localhost will be the machine.

Create windows short cut for this.
1. Create a short cut for PuTTY and change its command like below.
C:\Users\user\Desktop\putty.exe -ssh -pw -load
Source: http://www.jfitz.com/tips/putty_config.html

Find recursively and copy files in Unix

2011-07-07T12:52:00.000+05:30

I was trying to do a recursive search in Unix using find command and then copy all those files to a specific folder.

I found below command does that.

find . -name *2011-03-19* -exec cp {} /home/Reddy/logs/ \;

Important thing is, we need to escape the ending semi-colon.

{} is the place holder for putting the search result, i.e., the file name found.

Enable the tools disabled by virus

2008-10-01T20:16:00.005+05:30

If you got a virus usually it will disable the following things so that you can't be able to delete the virus.

It will disable Folder Options menu item from View menu, disables the Task Manager, and disables the Registry Editor.

You can enable all these from the Group Policy editor by yourself manually.

Go to Windows > Run > gpEdit.msc
Folder Options: Go to User Configuration > Administrative Templates > Windows Components > Windows Explorer > Removes the Folder Options menu item from the Tools menu. Disable this option. Now you should be able to see Folder Options in the View menu of your explorer window.
Task Manager: Go to User Configuration > Administrative Templates > System > Ctrl+Alt+Del Options > Remove Task Manger. Disable this option.
Registry Editor: Go to User Configuration > Administrative Templates > System > Prevent Access to Registry Editing Tools. Disable this option.

But, it is good to have alternatives for these things since viruses usually disables the default tools but not the alternative softwares.

You can use Process Explorer as alternative for Task Manager. Similarly you can use Explorer2 as alternative for default windows explorer. If you don't like Explorer2 many more explorer softwares are available, you can choose from any of those. I don't know alternatives for the Registry Editor. Please feel to share those you know in the comments section below.

Related Posts:
Stop viruses coming from Pen Drives
Remove Amvo.exe virus, Funny UST Scandal, Fun.exe DC.exe SVIQ.exe
Task Manager, Registry Accessing disabled?
Disable Autoplay, Messenger Service
Important steps while cleaning virus
What is this process

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Clean New Folder.exe, RegSvr.exe Virus

2008-05-12T15:15:00.000+05:30

Recently I got infected with this virus. This virus just shows a message when windows started, "Rundll.exe is not found.......", and infecting the pen drives for first few days. Not much harm. But after 4 or 5 days it is starting creating copies of virus file in many folders. The copy will be having the same name as the folder name and it also having folder icon, so that we will think it as another folder.

When I have searched Internet, I got the following link useful Am I Works. I have developed a tool for removing this virus.

Download New Folder virus removal tool, unzip it, and double click on RemoveVirus.bat file. Tell me if you get rid of virus in comments section.

Note: If you are not able to open Registry Editor (Win+R, regedit.exe), See Accessing Registry disabled?

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Related:
Stop Viruses coming from Pen drives
Task Manager Disabled?
Important Steps when cleaning viruses

Stop viruses coming from pen drives

2008-05-04T23:00:00.001+05:30

Now a days pen drives ( or USB drives ) became necessary. But there is a problem with these pen drives. They can be very easily infected by viruses. But we can not live without using pen drives.

You can be a bit more careful and prevent them infecting your system with different types of viruses.

First disable auto play in your system. This prevents viruses in the pen drive from running automatically when pen drives are inserted into the system. (Please note that this will disable auto playing of CDs also).
After inserting pen drive into the system open it in explorer mode only, don't open it in My Computer.

To open Explorer, press Win+E on your keyboard.
Or right click on My Computer, and select explorer.
If My Computer is already opened, click on 'Folders' in the tool bar (or View menu> Explorer Bar> Folders).

Always open pen drive by clicking on the pen drive name from the left pane only. Don't open from right pane.
Don't open the files you don't need. If you find any file suspicious, right click on file name and select properties. It will show complete details about that file. Don't rely on icons. Some viruses use folder icon to make us think that they are folders, and most probably we will double click on that to see what is there in that folder which actually executes the virus.

A little careful handling of pen drives will prevent a lot many viruses.

Related:
Remove Amvo.exe virus, Funny UST Scandal, Fun.exe DC.exe SVIQ.exe
Task Manager, Registry Accessing disabled?
Disable Autoplay, Messenger Service
Important steps while cleaning virus
What is this process

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Blogger plugins, widgets

2008-03-23T16:14:00.000+05:30

Have a look at the following site. It contains lot of tips and plug-ins for the blogger.com.

http://www.bloggerplugins.org

Related:
HTML Parser
Recent Posts widget for new Blogger
Related Posts Plug-in for Wordpress

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