Hello,
I'm just starting to program in Unix and I want to execute a binary. The program that I execute gets user input from standard input and prints it out. How would I run the program then print to the standard in?
I know that execl("./program"... ); works to run the program but I'm not sure how to give it input.
Just type "./program_name" at your console. No need to use execl. To read input, use fscanf function, for example
Code:#include <stdio.h> int main(){ int n; printf("Enter a number\n"); //read from standard input fscanf(stdin, "%d", &n); printf("Number entered is %d\n", n); return 0; }
Yes, but I need to be able to execute the program from within another program.
You would pass the program arguments. From the command line:
In the program:Code:$ program arg1 arg2 argn
I don't know how you run a program from another program in Linux. On my DOS machine it's system(), in stdlib.h. system() will probably work on your machine. But you can use execl() too if you want to.Code:int main(int argc. char *argv[]) { int x; if(argc > 1) for(x = 1; x < argc; x ++) { printf("\nArgument %i: %s", x, argv[x]); } else printf("\nNo arguments passed\n"); printf("\n"); return 0; }
dwk
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system() is a standard function - it should work for any correct C/C++ implementation. It will just execute the string given to it in the system shell - and that's where the dangers starts. If you know that your program will only be run on your OS, than most of the problems become moot points.
The problem is when you run System() it runs until the program ends, and if the program must have input then it will never end... Correct?
Perhaps popen is what you're looking for.
Quzah.
Hope is the first step on the road to disappointment.
I tried popen, but it didnt give me what I wanted, it printed what I wanted to the screen, but it didn't input it to the program.Originally Posted by quzah
