Category: Uncategorized

Show all cronjobs for all users

Posted on by David Saliba

This is a simple script to get all cronjbs for all users on a system

for someone in $(cut -f1 -d: /etc/passwd); do echo $someone; crontab -u $someone -l ; done

nJoy 😉

 

Dummy node script to respond 200 (or anything) to a call for testing purposes

Posted on by David Saliba

This is as bare a node App as you can make but it comes in handy when you want a . dummy server just to return 200s and or a JSON object at super fast speeds on small systems:

 

var express = require('express');

var app     = express();


app.get('*', function(req, res) {
    res.sendStatus(200);
});

app.listen('3000');

console.log('Magic happens on port 3000');

exports = module.exports = app;


Before running the js file run 
npm install express

to deploy express..

Thats it !

nJoy 😉

Installing node on old version of Ubuntu 10.04

Posted on by David Saliba 
 curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.31.0/install.sh | bash

logoff and log on

nvm ls-remote
nvm install v7.9.0
npm -v
node -v

Caveat :   Lots of node stuff fails to compile and run on such an old version of linux be warned…
Thats it you now have node and npm installed. nJoy 😉

send video from local device to a slave computer with ffmpeg

Posted on by David Saliba

setup service listener on viewer machine :

while : ; do ffplay -i tcp://192.168.xx.xx:1234?listen ; done

send video to it :

ffmpeg -re -i /dev/video1 -vcodec mpeg2video -f alsa -i hw:2,0 -ac 2 -s 1920×1080 -r 25 -strict -2 -f mpegts tcp://192.168.xx.xx:1234

where

192.168.xx.xx is the IP of the viewer where the ffplay is running.

1234 is the port used.

nJoy 😉

 

starting a machine in Docker with ports

Posted on by David Saliba 
docker run -p 800:80 -p 2222:22 -p  4443:443  -it 68715929d32a  /bin/bash

If ports do not work check :

sysctl net.ipv4.ip_forward

if  you get:

net.ipv4.ip_forward = 0

then issue :

sysctl -w net.ipv4.ip_forward=1
net.ipv4.ip_forward = 1if you get the error :

 
docker: Error response from daemon: driver failed programming external connectivity on endpoint amazing_williams (44e256a6039741b20e4124800702d9794d69fb6be9da71ba25059de4dd527121): COMMAND_FAILED: '/sbin/iptables -w2 -t nat -A DOCKER -p tcp -d 0/0 --dport 4443 -j DNAT --to-destination 172.17.0.2:443 ! -i docker0' failed: iptables: <strong>No chain/target/match by that name..</strong>

 

systemctl stop firewalld
systemctl mask firewalld

Created symlink from /etc/systemd/system/firewalld.service to /dev/null.

yum install iptables-services

Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.euserv.net
* epel: fr.mirror.babylon.network
* extras: ftp.fau.de
* updates: centos.fastbull.org
Resolving Dependencies
--> Running transaction check
---> Package iptables-services.x86_64 0:1.4.21-16.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================================================================================================================================================================================
Package Arch Version Repository Size
=============================================================================================================================================================================================================================================
Installing:
iptables-services x86_64 1.4.21-16.el7 base 50 k

Transaction Summary
=============================================================================================================================================================================================================================================
Install 1 Package

Total download size: 50 k
Installed size: 24 k
Is this ok [y/d/N]: y
Downloading packages:
iptables-services-1.4.21-16.el7.x86_64.rpm | 50 kB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : iptables-services-1.4.21-16.el7.x86_64 1/1
Verifying : iptables-services-1.4.21-16.el7.x86_64 1/1

Installed:
iptables-services.x86_64 0:1.4.21-16.el7

Complete!

systemctl enable iptables

Created symlink from /etc/systemd/system/basic.target.wants/iptables.service to /usr/lib/systemd/system/iptables.service.

service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[ OK ]

try :

docker run -p 800:80 -p 2222:22 -p 4443:443 -it 68715929d32a /bin/bash

Gather metatdata on AWS from within EC2 instance.

Posted on by David Saliba

So I need to get information about a particular set of machines in the cloud (AWS).

EC2_INSTANCE_ID="`wget -q -O - http://instance-data/latest/meta-data/instance-id || die \"wget instance-id has failed: $?\"`"
test -n "$EC2_INSTANCE_ID" || die 'cannot obtain instance-id'
EC2_AVAIL_ZONE="`wget -q -O - http://instance-data/latest/meta-data/placement/availability-zone || die \"wget availability-zone has failed: $?\"`"
test -n "$EC2_AVAIL_ZONE" || die 'cannot obtain availability-zone'
EC2_REGION="`echo \"$EC2_AVAIL_ZONE\" | sed -e 's:\([0-9][0-9]*\)[a-z]*\$:\\1:'`"

 

nJoy 😉

 

 

package.json sample

Posted on by David Saliba

This is the basic structure for a node.js package file

{
"name": "Express-Basic",
"description": "Demonstrating Express",
"version": "0.0.1",
"private": true,
"dependencies": {
"express": "3.x"
}
}

nJoy 😉