#May 2016

Linux

OpenSSL generates keys

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Sometimes, you have to generate the keys for your projects. You can use the coomand below:

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openssl req \
       -newkey rsa:2048 -nodes -keyout domain.key \
       -x509 -days 365 -out domain.crt

Create a Private CA

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openssl genrsa -out ca-priv-key.pem 2048

Public CA

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openssl req -config /usr/lib/ssl/openssl.cnf -new -key ca-priv-key.pem -x509 -days 1825 -out ca.pem

Sign Keys

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openssl genrsa -out swarm-priv-key.pem 2048

CSR

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openssl req -subj "/CN=swarm" -new -key swarm-priv-key.pem -out swarm.csr

Certs

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openssl x509 -req -days 1825 -in swarm.csr -CA ca.pem -CAkey ca-priv-key.pem -CAcreateserial -out swarm-cert.pem -extensions v3_req -extfile /usr/lib/ssl/openssl.cnf

 

Nguyen Sy Thanh Son

2

Linux

PostgreSQL Command Line

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There are many different between MYSQL and PostgreSQL. One of them is PostgreSQL is Command Lines.  I write as below for the reference as needed.

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What motivates me? The fear of being average

Show databases

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\l
#or
\list

Connect to database

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\connect database_name

List all tables

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\d+

Show table schema

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\d+ tablename

Dump a table

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pg_dump --username postgres -f /tmp/table_name.sql -d database_name -t table_name

Import a table or database:

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pgsql database_name < file_name

Time comparison:

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SELECT * FROM users WHERE created_at >= '{}'::date AND created_at < ('{}'::date + '1 day'::interval)

 

Nguyen Sy Thanh Son

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Linux

Backup Cassandra to S3 SWS

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This post is just a small post. I would like to show you a way to incremental backup Cassandra to S3. In my case, I use a opensource named Cassandra_Snapshorter.

To know how to install it in your machine, you can refer to https://github.com/tbarbugli/cassandra_snapshotter

Now, we create a backup script

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#!/bin/bash
 
time=`date +"%Y-%m-%d %H:%M:%S"`
date=`date +"%Y-%m-%d-%H"`
 
echo Backup Cassandra - $time ...
 
/usr/local/bin/cassandra-snapshotter --s3-bucket-name=dev-backup \
                      --s3-bucket-region=ap-southeast-1 \
                      --s3-base-path=cassandra \
                      --aws-access-key-id=xxxx \
                      --aws-secret-access-key=xxxxx \
                      --s3-ssenc \
                      backup \
                      --hosts=localhost \
                      --user=ubuntu \
                      --cassandra-conf-path=/home/ubuntu/cassandra/conf\
                      --cassandra-bin-dir=/home/ubuntu/cassandra/bin\
                      --new-snapshot
 
wait
 
echo "\n"
echo DONE !!!
echo -----------------------------------------------------------------

After that, We will create a job in Crontab to run backup every night.

Nguyen Sy Thanh Son

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Linux

Convert WMV to MP4 in Ubuntu

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Sometime, I use EZVID to create a video. The size of the file created by EZVID usually is bigger than my expectation. So I have to use avconv command to convert that video.

To install avconv in Ubuntu Server, we use command:

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sudo apt-get install libav-tools

To convert the file, we use the command below:

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avconv -i input.wmv -c:v libx264 -b:a 64k -strict experimental output.mp4

 

Nguyen Sy Thanh Son

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