Linux timers...
 

What are the Linux system calls have to be used to write user-space timers?
And please suggest me how to write concurrent timers, i.e, have to create four separate timers and it must run simultaneously.

Can you provide more context? In the case of a shell function, you may want to check out the "sleep" command.

Do you need timers with interrupts to be used in c program?

Look at the timer_create API.

Linux Timers...
 

I'm writing a C program that require concurrent Timers logic. Can anybody share the logic? or any open-source concurrent timers?