tmux

Quick tmux commands:

NOTE: [ consider all following key is after the combination (ctrl-b) [ In standard configuration ]

split tmux vertically     : %
split tmux horizontally : "

Moving between panes:
Move Left                     : left arrow or {
Move Right                   : right arrow or }
Move Up                       : up arrow
Move Down                  : down arrow
next pane                       : o
show number of each panes and move: b q + number


Resizing panes

You may want to resize panes to fit your need. Here’s a list how to do that :

(Ctrl-b) + : then type resize-pane -D (Resizes the current pane down)
(Ctrl-b) + : then type resize-pane -U (Resizes the current pane upward)
(Ctrl-b) + : then type resize-pane -L (Resizes the current pane left)
(Ctrl-b) + : then type resize-pane -R (Resizes the current pane right)
(Ctrl-b) + : then type resize-pane -D 5 (Resizes the current pane down by 5 cells)
(Ctrl-b) + : then type resize-pane -U 5 (Resizes the current pane upward by 5 cells)
(Ctrl-b) + : then type resize-pane -L 5 (Resizes the current pane left by 5 cells)
(Ctrl-b) + : then type resize-pane -R 5 (Resizes the current pane right by 5 cells)
(Ctrl-b) + : then type resize-pane -t 2 5 (Resizes the pane with the id of 2 down by 5 cells)
(Ctrl-b) + : then type resize-pane -t -L 5 (Resizes the pane with the id of 2 left by 5 cells)

press (Ctrl-b) + : resize-pane -D 13 to make it down for 13 cells.


create more window: ctrl-b c

(Ctrl-b) + n : Move to next window
(Ctrl-b) + p : Move to previous window
(Ctrl-b) + w : Interactively choose the window (useful if you have more than 2 window)


Detached: ctrl-b d

Listing the tmux session: tmux ls

attaching the tmux session: tmux attach -t <session-name>

### sync tmux panes ###

Ctrl-B :
setw synchronize-panes on
clear history

su as another user

sudo su - poweruser << EOF
whoami
EOF

Interesting motd with figlet or toilet

What if you want to have interesting motd?

You can do these interesting motd using figlet.

Example:

You Just need to install [ toilet ] and try these interesting output.

sudo apt-get install toilet

ansible-playbook for docker cassandra cluster.

The following command will create a cassdb cluster using ansible.
#####
---
- hosts: all
  tasks:
  - name: coping the file to all the docker server
    template: src=cassandra.yaml.j2 dest=/tmp/cassandra.yaml
  - name: running some command
    raw: sudo docker run -i -t -d --name cassdb --net host -v /cassdata:/var/lib/cassandra cassdb /bin/bash; containerID=`sudo docker inspect -f '{{.Id}}' cassdb`; sudo cp /tmp/cassandra.yaml /var/lib/docker/aufs/mnt/$containerID/etc/cassandra/cassandra.yaml; sudo docker exec cassdb rm -rf /var/lib/cassandra/*; sudo docker exec cassdb /etc/init.d/cassandra start



#####
command would be:

ansible-playbook  docker-inventory_hosts install_cassandra_playbook.yml



########

NOTE: Following is the variable that I have added in the "cassandra.yaml.j2" file, that need to be interpolated, dynamically.

cluster_name: {{ cluster_name }}
          - seeds: {{ hostvars[groups['docker-akamai'][0]]['ansible_eth0']['ipv4']['address'] }}
listen_address: {{ ansible_default_ipv4.address }}
broadcast_rpc_address: {{ ansible_default_ipv4.address }}


### my cassdb docker image:

docker pull amitmund/cassdb:latest

#######

$ sudo docker exec cassdb nodetool status
Note: Ownership information does not include topology; for complete information, specify a keyspace
Datacenter: BLR
===============
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address        Load       Tokens  Owns    Host ID                               Rack
UN  192.168.1.10  54.93 KB   256     37.4%   e7915e97-babf-49fd-bcdf-4434b4443fba  R1
UN  192.168.1.11  261.03 KB  256     32.7%   a0589928-f5eb-496f-8456-5018fabb75ca  R1
UN  192.168.1.12  169.35 KB  256     29.9%   219d1439-fd0d-4ea9-ae03-4d25fe0334fc  R1

How to do port forwarding in virtual box.

How to do port forwarding in virtual box.

1. select your vm that you want for port forwarding.

NOTE: Make sure the vm is in stop mode.

2. select “settings"

3. select “Network"

4. select any free Adapter. “Lets say Adapter 2"

5. enable Enable Network Adapter 

6. In Attached to dorpdown, select NAT

7. Select Advanced

8: In Adapter Type: Select “Paravirtualized Network (virtio-net)”  [ This is important ]

9. Select “Port Forwarding"

10. In Right hand part of the “port forwarding” dialog box, select “+"

11. Provide the :

  Name: Anything you want. example for ssh, say “ssh"

  Protocol: Type of protocol [ for ssh: TCP ]

  Host IP: provide hostname from which host you want to connect to [ over here: 127.0.0.1 ]

  Host Port: On what port of that Host you want to connect to remote port [ example: 60022 ]

  Guest IP: Leave it Blank

  Guest Port: To what port you want to connect from the above host. [ for ssh, the default 22 ]

html_frame

For the example of 8 section.


<!DOCTYPE html>
<html>


<frameset cols="50%,*" rows="25%,25%,25%,25%">
  <frame src="http://url1/">
  <frame src="http://url2">
  <frame src="http://url3">
  <frame src="http://url4">

  <frame src="http://url5">
  <frame src="http://url6">
  <frame src="http://url7">
  <frame src="http://url8">

</frameset>

</html>

reading a file using golang

Example 1:

$cat run readFile.go 

package main

import(

"io/ioutil"

)

func main() {

contents,_ := ioutil.ReadFile("readFile.go")

println(string(contents))

}

Example 2:

$ cat fileRead.go 

package main

import(

"io/ioutil"

)

func main() {

contents,_ := ioutil.ReadFile("/etc/passwd")

println(string(contents))

}