Install R Programming Language in Ubuntu

This post describe about installation steps for R- Programming Language.

For Windows we have direct exe file but for Linux its in a single click way but you can still do it below commands easily.

Open your terminal and type below commands as root user.

echo "
deb https://cloud.r-project.org/bin/linux/ubuntu xenial/
deb https://cloud.r-project.org/ trusty-backports main restricted universe" >> /etc/apt/sources.list
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 51716619E084DAB9
sudo apt-get update
sudo apt-get install -y r-base r-base-dev
sudo apt-get install r-cran-boot r-cran-class r-cran-cluster r-cran-codetools r-cran-foreign r-cran-kernsmooth r-cran-lattice r-cran-mass r-cran-matrix r-cran-mgcv r-cran-nlme r-cran-nnet r-cran-rpart r-cran-spatial r-cran-survival r-cran-rodbc

If any questions please dont hesitate to ask.

Thank you.

JVMMON help commands

Hello ,

jvmmon is an excellent tool for JBOSS administrators and please find below list of commands for jvmmon

 Print commands: __________________________

  print arenastat                             - Prints brief arena statistics
  print arenastat full                        - Prints detailed arena statistics
  print class statistic                       - Prints class statistics of a VM
  print cluster memory information            - Prints information about the memory consumption of the cluster
  print codeblobs                             - Prints information about code blobs with specified name
  print debugging information                 - Prints information about the debugging state of a VM
  print detailed class statistic              - Prints detailed class statistics of a VM
  print dll info                              - Prints information about the loaded shared libraries of a VM
  print flight recorder                       - Prints part of the flight recorder of a VM
  print gc history                            - Prints the GC history of a VM
  print hs_err_info                           - Prints the hs-err-info of a VM
  print jit info                              - Prints information about JIT compiler and code cache
  print mallocstat                            - Prints malloc statistics
  print mallocstat internals                  - Prints internals for malloc statistics
  print memhist                               - Prints memory history
  print performance information               - Prints information about the performance of a VM
  print signal handlers                       - Prints currently active signal handlers
  print stacktrace                            - Prints the stacks of all threads in a VM
  print symbol info                           - Prints information about symbols and interned strings of a VM
  print system information                    - Prints system information
  print system properties                     - Prints VM system properties
  print trace flags                           - Prints the active trace flags of a VM
  print virtualization info                   - Prints the platform virtualization info
  print vm compressed class space information - Prints information about the compressed class space of a VM
  print vm information                        - Prints information about a VM
  print vm memory information                 - Prints information about the memory consumption of a VM

__ Dump commands: ___________________________

  dump class statistic                        - Dumps class statistics of a VM
  dump codeblobs                              - Dumps information about code blobs with specified name
  dump detailed class statistic               - Dumps detailed class statistics of a VM
  dump dll info                               - Dumps information about the loaded shared libraries of a VM
  dump gc history                             - Dumps the GC history of a VM
  dump heap                                   - Dumps the heap of a VM
  dump heap with info                         - Dumps the heap and additional information describing the heap of a VM
  dump hs_err_info                            - Dumps the hs-err-info of a VM
  dump jit info                               - Dumps information about JIT compiler and code cache
  dump safepoint state                        - Dumps information about the safepoint state of the specified VM
  dump stacktrace                             - Dumps the stacks of all threads in a VM
  dump stacktrace with info                   - Dumps the stacks of all threads with additional information
  dump symbol info                            - Dumps information about symbols and interned strings of a VM

__ GC commands: _____________________________

  force gc                                    - Forces a full garbage collection
  force max gc                                - Forces a maximum compaction garbage collection
  retrieve complete gc history                - Retrieves the complete GC history of a VM into a local file

__ JIT commands: ____________________________

  compile                                     - Forces compilation of the specified method(s)
  deoptimize                                  - Deoptimizes all activations of the specified method(s)
  deoptimizeall                               - Deoptimizes all methods
  osrcompile                                  - Forces osr compilation of the specified method

__ VM commands: _____________________________

  change command line flag                    - Changes command line flags of a VM
  crash vm                                    - Crashes a VM
  exit vm                                     - Exits a VM
  mallocstat reset                            - Resets malloc statistics value
  mallocstat startcap                         - Starts malloc statistics capture
  mallocstat stopcap                          - Stops malloc statistics capture
  set core size to max                        - Set current soft limit of core size to hard limit
  set debugging port range                    - Sets debugging port range of a VM
  set trace flags                             - Sets trace flags of a VM
  start debugging                             - Starts on-the-fly debugging
  stop command line profiling                 - Stops command line profiling of a VM
  stop debugging                              - Stops on-the-fly debugging

__ VM selection commands: ___________________

  display vms                                 - Displays the VMs in the cluster
  select vm                                   - Selects a VM (in the cluster)
  select vm all                               - Selects all VMs in the cluster

__ Jvmmon commands: _________________________

  exit                                        - Exits Jvmmon
  help                                        - Shows the help text
  history                                     - Shows a list of the commands executed
  print to console                            - Redirect print commands to console output
  print to file                               - Redirect print commands to local file
  quit                                        - Quits Jvmmon
  help ""                            - Displays detailed help about the specified command
  !                                           - Repeats the last command
  !!                                          - Repeats the last command
  !N                                          - Repeats command with number N in history
  !TEXT                                       - Repeats command that started with TEXT

Hope it will helps. 

Python Object reference well explained with list

Assume you have a list and you want to make exact copy of the list.

What command you will use in python to copy a list from another list.

I used List1=List2 and List1 got copied as exactly as List2 but what happen internally is they have shared command object reference location.

Dont believe ? then lets try and try to see both lists location with id function id()

I mean do as  id(List1) and id(List2) , you will find command location for these two which means they are sharing common location and what ever operations you do they will reflect on both lists.And this is completely harmful and dangerous.

So to avoid this list copying can be done in other methods where two list will have two different object locations.

They are

list2=copy.copy(list1)
(or)
list2=list1[:]
(or)
list2=list(list1)

and for more information about object reference understanding in python I recommend you to read these

http://stackoverflow.com/questions/36244451/how-to-program-python-variable-to-point-different-reference-location-but-same-va/36244490#36244490

http://www.python-course.eu/python3_variables.php

How to get full application propery reports by using jvmmon ?

Hello ,

Let come straight to the point.

If you want to see right now with what properties your Jboss application servers are running ,

Please type jvmmon and choose current PID of your JBOSS process.

Then type print system properties

It will flood your stdout , copy and paste it in a file and you can use to analyse.

else

you can save it to a file in your system.

$ print to file
file = /tmp/fromjvmmon
$ print system properties
-- printed to local file /tmp/fromjvmmon
$ exit

and to take thread dump use 

jvmmon

$ print to file

file =/tmp/threaddump

$print stacktrace

it will autosave threaddump in the above location

and similarly to take heap dump. 

type

jvmmon

$dump heap

it will dump heap automatically into location as mentioned in run.conf

Thank you.

Regards
Raja

Suspended Jobs vs Running jobs in Linux

Background Job : A job which is running background in the same shell. You can use bg command to see any background jobs.

Foreground job : A Job which is running in the same shell right before your eyes.

Suspended Job : Its a stopped/pause job but you can resume their running.

Let me explain with example very clealy

virt00# sleep 180
^Z
zsh: suspended  sleep 180
virt00# jobs
[1]  + suspended  sleep 180
virt00# bg
[1]  + continued  sleep 180
virt00# fg
[1]  + running    sleep 180
^Z
zsh: suspended  sleep 180
virt00# jobs
[1]  + suspended  sleep 180
virt00#

I have started a Job named sleep 180 then I stopped with CTRL+Z . right now my job is in suspended mode.

I see it by typing jobs command. Now I want to resume its running in background so I typed bgcommand then it will move from suspended state to running state but in background it will run.

now I typed command fg to bring it foreground , now job wont get stepped but it will pull from background jobs queue and push into foreground jobs queue.

So yes background jobs and foreground jobs always are in running state.

Deny SSH access to particular users

We all know SSH is very famous and the best service for remote access.

Today I am going to tell you how to block or allow only particular users or group from SSH access.

open sshd_config file as per your environment

in Debian

vim /etc/ssh/sshd_config

Then add below line to enable access for only below users

AllowUsers username1 username2

to deny access for only below users add a line as

DenyUsers username1 username2

as in the same way

AllowGroups group1 group2

and to deny groups

DenyGroups group1 group2

 But there is something very important you have to follow here. It is the order of mentioning.

From manpage of SSH 

The allow/deny directives are processed in the following
      order: DenyUsers, AllowUsers, DenyGroups, and finally
      AllowGroups.

So first mention DenyUsers and then AllowUsers then only it will works and same for DenyGroups and AllowGroups

Hope it helps.

How to see IOWAIT in Linux

Hello ,

You can use sar command.

in Ubuntu you can install it with

sudo apt-get install systat

and enable data collecting

sed -i 's/ENABLED="false"/ENABLED="true"/' /etc/default/sysstat

start service with

 

/etc/init.d/sysstat start

To see I/O latency type command as

sar 1 1

that means it will give two responses with 1 sec as interval.

Example :

root@virt01:~# sar 1 3
Linux 3.19.0-42-generic (virt01.ubuntu.com)     13/02/16        _x86_64_        (1 CPU)


12:26:23        CPU     %user     %nice   %system   %iowait    %steal     %idle
12:26:24        all      0.00      0.00      0.00      0.00      0.00    100.00
12:26:25        all      0.00      0.00      0.99      0.00      0.00     99.01
12:26:26        all      2.02      0.00      0.00      0.00      0.00     97.98
Average:        all      0.67      0.00      0.33      0.00      0.00     99.00
root@virt01:~#

Hope that helps.