System Calls

I am working with UNIX operating system. What are systems calls in UNIX means.Are they sepearte set of commands in UNIX.

As far as my understandiing goes, these are functions that can be used to control the behaviour of UNIX. These functions can be called from a C/C++ programs.

I am not too well versed with the concept. The following links might be helpful.

[url=http://caml.inria.fr/pub/docs/manual-caml-light/node17.html]The unix library: Unix system calls[/url]
[url=http://www.cs.cf.ac.uk/Dave/C/node15.html]C, UNIX and Standard Libraries[/url]

Hope that helped.
Cheers,
Kalayama

System calls are functions in kernel. it requests the OS to do some thing for user program.
The commands we give in shell invokes a system call to kernel to perform the operation.

This is another good link for this topic. It correlates C,Unix and Unix System Calls.
[url=http://www.cs.cf.ac.uk/Dave/C/CE.html]Programming in C[/url]

Friends after studying this topic even I want to learn a lot on system calls.Can someone out here suggest a good book to learn about system calls covering C and UNIX operating system.

I don't know of a hard covered book. buit the link pasted above in my previous post is about the best you can get! That link covers some awesome topics and explains them beautifully.

Cheers!
Kalayama

You could checkout this site. linux.about.com thats a good one.
[url]http://linux.about.com/library/cmd/blcmdl2_syscalls.htm[/url]
Cheers,
-Chandan.

I thnk Unix Internals by VAHALIA is very good book, explaining the internals of UNIX covering signals, Process , file systems, SIGNALs...