Code Tips and Snippets

Not yet member?
Click here to register.
Only members can post comments

News on "C Language"

VirtualBox bridged mode: automatically nic select and VM start
Posted by pk on Sunday, October 09 2016 - 10:47:11
2 stars levelC LanguageLinux operating systemWindows operating system

If like me, you use a VirtualBox VM for developing server applications, you certainly have configured your VM with your network interface in bridged mode.

When you have to move your VM on a Laptop PC, and after that, each time you switch from a wired connection to a Wireless one, you definitely have been annoyed, having to update the network adapter on which the network is bridged.

You will see in this post how to develop a mini C program that allows you to switch automatically to the correct network interface and then start the VM.

Optimizing your C/C++ code by using register!
Posted by pk on Saturday, November 07 2015 - 15:48:25
2 stars levelC Language

Monday april 06, 2020 Update: Obsolete article
Last tests had been done on ubuntu 12.04...
gcc Optimizer doesn't need anymore register
What has been true during 30 years is now no more true!

During the seventies, at the very beginning of the C language, the register keyword has been introduced in order to allow the programmer to give hints to the compiler, telling it that the variable would be used very often, and that it should be wise to keep it’s value in one of the processor’s internal register.

Nowadays, optimizers are much more efficient than programmers to determine  variables  that are more likely to be kept into registers, and the optimizer does not always take the programmer’s hint into account.

So many people wrongly recommend not to use the register keyword.

Let’s see why!

Run php (or other) scripts with suid root permission
Posted by pk on Sunday, September 07 2014 - 12:45:15
5 stars levelC Languagephp languageLinux operating system

Who never had the need to run some php (or other) scripts, which require access to data with root privilege, in the context of unprivileged users ( apache for an example ).

In fact, it is very easy to achieve this with a C program.

But in recent Linux distributions, for a script (other than bash/sh/...), it is now forbidden for so-called security considerations.

Maybe this would be justified on a server where multiple users have local access, with permissions that are uncontrolled by the administrator…

On a personal server, where only services (web, email, etc.) are offered to the public, I think that it is completely unfounded!

Let's see how to bypass totalitarian restrictions of current distributions.

yakpro rulez!

Site has been updated on Wednesday, January 19 2022 - 09:43:57