echo

June 17th, 2009, 10:30 pm

can anyone please tell me what is the internal working of echo command....... i mean how does it display anything we entered.....

June 17th, 2009, 10:53 pm

Just about every programming language has some kind of text output function, such as printf in C. It's quite obvious that the echo command uses this to display the text you enter.

June 17th, 2009, 11:03 pm

casablanca wrote:

Just about every programming language has some kind of text output function, such as printf in C. It's quite obvious that the echo command uses this to display the text you enter.

thanx for ur response.
i m not looking for what does echo do, i wanna know how does it display..... what is the roll of shell, kernal etc. in this .........

June 17th, 2009, 11:14 pm

The shell basically reads user input and invokes some function based on the command. In case of "echo", it calls an output function such as printf, which in turn uses the kernel's services to print characters on the screen. The kernel itself uses device drivers (the display driver in this case) to communicate with the hardware.

Hope I answered your question.