Why does appending ./ to a file execute the program while just typing the program does not

Question

To be more specific, what I mean is:

Suppose I have a python script called test.py with a proper shebang on the first line, say

#!/usr/bin/env python

print 'this works'

In the shell, when I type:

$ test.py

Nothing happens, but when I type:

$ ./test.py

The command is invoked and prints "this works".

Why is that? I thought "." just meant the current directory. Why would having a ./ suddenly mean we want to execute whatever comes next? Thanks.

`./test.py` does mean *current directory*. The problem is that `test.py` doesn't. — Álvaro González, Jan 03 '14 at 08:49

score 4 · Accepted Answer · answered Jan 03 '14 at 08:30

The shell only looks for executables in the path (try echo $PATH in the shell to see its value). If . is not in the path, you'll have to give the explicit path to the executable. Not having . in the path is a good idea: imagine somebody managed to put an executable named ls in your home directory!

score 1 · Answer 2 · answered Jan 03 '14 at 08:31

1

Because the current directory (where you had saved test.py) is not in your $PATH environment variable.

$PATH is searched for executables when you try to run one.

answered Jan 03 '14 at 08:31

Zsolt Botykai

50,406
14
85
110

Why does appending ./ to a file execute the program while just typing the program does not

2 Answers2