Question

40

My program cannot run with "command not found" error

rated 0 times [ 40] [ 0] / answers: 1 / hits: 121802 / 3 Years ago, tue, july 13, 2021, 6:18:44

I just switched from Windows to Ubuntu 11.10.

I wrote the following code in C with the text editor and saved it as HelloWorld.c in Documents.

#include <stdio.h>

int main()

{

    printf("Hello World!

");

    return 0;

}

And I started the Terminal and enter the following commands:

cd Documents



gcc HelloWorld.c

A file called a.out, which, after some search on Google, is the executable. I entered this command:

a.out

But I get

a.out: command not found

Which step did I do wrongly?

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biryanrownies

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answered 3 Years ago untroo · Accepted Answer

Since you're running an executable in the current working directory, you should prefix it with ./. So for your program run it as ./a.out.

Explanation

The terminal searches for executables in $PATH. This is a Unix environment variable that lists directories containing system binaries (such as ls, echo, or gcc). If you call an executable that's not in a $PATH directory (such as a.out), you need to indicate its absolute path in the file system.

In the terminal . is a synonym for the current working directory, thus ./a.out. You could equally well call /home/yihang/Documents/a.out.