John's blog

Talking about technology (mostly)

About Jay Jay

Hi there. My name is John Elliot V. My friends call me Jay Jay. I talk about technology on my blog at blog.jj5.net and make videos about electronics on my YouTube channel @InTheLabWithJayJay.

How to downgrade a package in Debian using apt-get and apt-cache

Posted on 2015-09-08 [Tuesday] by Jay Jay

See here. Basically:

dpkg --list
apt-cache showpkg packagename
apt-get install packagename=version
echo "packagename hold" | sudo dpkg --set-selections

Administering PostgreSQL

Posted on 2015-09-07 [Monday] by Jay Jay

So I found this article which said:

 $ sudo -u postgres psql

 postgres=> alter user postgres password 'apassword';
 postgres=> create user your-user createdb createuser password 'passwd';
 postgres=> create database your-db-name owner your-user;
 postgres=> \q

Note: to enable password logins for the ‘postgres’ admin account, edit: /etc/postgresql/9.4/main/pg_hba.conf and after this line:

local   all             postgres                                peer

Add this line:

local   all             postgres                                md5

Converting a C++ std::string to char*

Posted on 2015-09-07 [Monday] by Jay Jay

So it turns out there is a std::string->c_str function. Note: I’m pretty sure this char[] will be deleted when the std::string is deleted…

C++ PostgreSQL example

Posted on 2015-09-07 [Monday] by Jay Jay

Just followed this tutorial on how to create a basic C++ app that talks to a PostgreSQL database…

Code Assistance for C++ in NetBeans: define __cplusplus

Posted on 2015-09-07 [Monday] by Jay Jay

See here:

Go to Tools->Options
Select C/C++ menu
Select Code Assistance tab
Select C++ Compiler tab
In Macro Definitions list view, locate __cplusplus and change its value from 199711L to 201103L
Click OK button