command execution

[happy-linux]

when a command is enterted how does it display the output on screen..... what is the internal working???

[Lakshmipathi]

when a command is enterted how does it display the output on screen..... what is the internal working???

I assume commands are nothing but C program, These executable are place under specific path.
Example : main,c

int main(){
printf("\n Linux Programmers Paradise\n");
return 1;
}

Compile it

gcc -o main main.c

move to pre-defined path

mv main /usr/bin

Now open any terminal and run the "command" called main.If You upload this "main" command to sites like sourceforge.net.If people find the software useful ,they will download your program and use it.

That's how open source works

[happy-linux]

I assume commands are nothing but C program, These executable are place under specific path.
Example : main,c

Now open any terminal and run the "command" called main.If You upload this "main" command to sites like sourceforge.net.If people find the software useful ,they will download your program and use it.

That's how open source works

thanx, but my question is different, i wanna know how does a OUTPUT display on SCREEN

e.g. if i typed
$ echo hello
hello will be displayed, how this happens........

[Lakshmipathi]

e.g. if i typed
$ echo hello
hello will be displayed,

int main(int argc,char * argv[]){
printf("%s",argv[1]);
return 1;
}

compile it as

gcc - echo2 main.c

Run it as

./echo2 hello

[Lakshmipathi]

By fault screen is your output device - Keyboard is your input device

if you want know about how printf() works then i would suggest to check with some system programming books like rebecca thomas Unix Programmer Guide

[happy-linux]

By fault screen is your output device - Keyboard is your input device

if you want know about how printf() works then i would suggest to check with some system programming books like rebecca thomas Unix Programmer Guide

can u plz suggest me some links on internet........... i wanna know abt the internal working of eho command of linux.

[Lakshmipathi]

If you want to know about working for echo ,then better check its source code with coreutils.

echo source code :
http://www.google.com/codesearch/p?h...utils%20lang:c

coreutils download page
Coreutils - GNU core utilities

All the best

[happy-linux]

If you want to know about working for echo ,then better check its source code with coreutils.

echo source code :

coreutils
All the best

thankyou very very much for the links........ if u know more abt echo then send me the updates.

thanx again.