Merge pull request #341 from realpython/python-shebang

Python Shebang Q&A

Author: KateFinegan

python-shebang/README.md

@@ -0,0 +1,215 @@
+# Executing Python Scripts With a Shebang
+
+This folder holds the code for the Real Python tutorial entitled [Executing Python Scripts With a Shebang](https://realpython.com/python-shebang/).
+
+## Sample Scripts
+
+### Python
+
+Command:
+
+```shell
+$ ./hello.py
+Hello, World!
+```
+
+### Perl
+
+Command:
+
+```shell
+$ ./hello.pl
+Hello, World!
+```
+
+### JavaScript
+
+Command:
+
+```shell
+$ ./hello.js
+Hello, World!
+```
+
+### Java
+
+Command:
+
+```shell
+$ ./hello.j
+Hello, World!
+```
+
+## Custom Interpreter
+
+Install your custom interpreter of a popular [esoteric programming language](https://esolangs.org/wiki/Esoteric_programming_language) into a Python virtual environment:
+
+```shell
+$ cd interpreter/
+$ python3 -m venv venv/
+$ source venv/bin/activate
+(venv) $ python -m pip install .
+```
+
+Execute sample scripts through the esoteric language interpreter while using the virtual environment:
+
+```shell
+(venv) $ cd scripts/
+```
+
+### Towers of Hanoi
+
+```shell
+(venv) $ ./hanoi.b
+
+                         Towers of Hanoi in Brainf*ck
+              Written by Clifford Wolf <http://www.clifford.at/bfcpu/>
+
+                     
+                       
+                         
+                           
+                                                             
+                xXXXXXx                                        
+      xXXXXXXXXXXXXXXXXXXXXXXXXXx                         xXx    
+    xXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx                 xXXXXXXXXXXXXXx
+  xXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx             xXXXXXXXXXXXXXXXXXx
+  -----------------------------------     -----------------------------------
+
+
+
+
+
+                                         
+                                           
+                                  xXXXXXXXXXx
+                            xXXXXXXXXXXXXXXXXXXXXXx
+                      -----------------------------------
+```
+
+
+### Sierpiński Triangle
+
+```shell
+(venv) $ ./sierpinski.b
+                               *
+                              * *
+                             *   *
+                            * * * *
+                           *       *
+                          * *     * *
+                         *   *   *   *
+                        * * * * * * * *
+                       *               *
+                      * *             * *
+                     *   *           *   *
+                    * * * *         * * * *
+                   *       *       *       *
+                  * *     * *     * *     * *
+                 *   *   *   *   *   *   *   *
+                * * * * * * * * * * * * * * * *
+               *                               *
+              * *                             * *
+             *   *                           *   *
+            * * * *                         * * * *
+           *       *                       *       *
+          * *     * *                     * *     * *
+         *   *   *   *                   *   *   *   *
+        * * * * * * * *                 * * * * * * * *
+       *               *               *               *
+      * *             * *             * *             * *
+     *   *           *   *           *   *           *   *
+    * * * *         * * * *         * * * *         * * * *
+   *       *       *       *       *       *       *       *
+  * *     * *     * *     * *     * *     * *     * *     * *
+ *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *
+* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+```
+
+
+### Factorial
+
+```shell
+(venv) $ ./factorial.b
+1
+1
+2
+6
+24
+120
+720
+5040
+40320
+362880
+3628800
+39916800
+479001600
+6227020800
+87178291200
+1307674368000
+20922789888000
+355687428096000
+6402373705728000
+121645100408832000
+2432902008176640000
+51090942171709440000
+1124000727777607680000
+25852016738884976640000
+620448401733239439360000
+15511210043330985984000000
+403291461126605635584000000
+10888869450418352160768000000
+^C
+```
+
+### Fibonacci Sequence
+
+```shell
+(venv) $ ./fib.b
+0
+1
+1
+2
+3
+5
+8
+13
+21
+34
+55
+89
+144
+233
+377
+610
+987
+1597
+2584
+4181
+6765
+10946
+17711
+28657
+46368
+75025
+121393
+196418
+^C
+```
+
+### ROT-13
+
+This is an interactive script that will expect you to provide input from your keyboard:
+
+```shell
+(venv) $ ./rot13.b 
+This text will be encrypted.
+Guvf grkg jvyy or rapelcgrq.
+```
+
+### Hello World
+
+```shell
+(venv) $ ./hello.b 
+Hello World!
+```

python-shebang/hello.j

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+#!/usr/bin/env -S java --source 11
+
+public class Hello {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!");
+    }
+}

python-shebang/hello.js

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+#!/usr/bin/env node
+
+console.log("Hello, World!")

python-shebang/hello.pl

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+#!/usr/bin/env perl
+
+print("Hello, World!\n");

python-shebang/hello.py

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+#!/usr/bin/env python3
+
+print("Hello, World!")

python-shebang/interpreter/pyproject.toml

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+[build-system]
+requires = ["setuptools>=64.0.0", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "brainf"
+version = "1.0.0"
+
+[project.scripts]
+brainf = "brainf:main"

python-shebang/interpreter/scripts/factorial.b

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+#!/usr/bin/env brainf
+
+>>>>++>+[
+    [
+        >[>>]<[>+>]<<[>->>+<<<-]>+[
+            [+>>[<<+>>-]>]+[-<<+<]>-[
+                -[<+>>+<-]++++++[>++++++++<-]+>.[-]<<[
+                    >>>[[<<+>+>-]>>>]<<<<[[>+<-]<-<<]>-
+                ]>>>[
+                    <<-[<<+>>-]<+++++++++<[
+                        >[->+>]>>>[<<[<+>-]>>>+>>[-<]<[>]>+<]<<<<<<-
+                    ]>[-]>+>>[<<<+>>>-]>>>
+                ]<<<+[-[+>>]<<<]>[<<<]>
+            ]>>>[<[>>>]<<<[[>>>+<<<-]<<<]>>>>>>>-[<]>>>[<<]<<[>+>]<]<<
+        ]++>>
+    ]<<++++++++.+
+]
+
+This program computes the factorials (https://oeis.org/A000142). Because this
+sequence is infinitely long, this program doesn't terminate on its own; you will
+have to kill it. This program is much faster than my earlier factorial program.
+
+[factorial2.b -- compute factorials
+(c) 2019 Daniel B. Cristofani
+http://brainfuck.org/]

python-shebang/interpreter/scripts/fib.b

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+#!/usr/bin/env brainf
+
+>++++++++++>+>+[
+    [+++++[>++++++++<-]>.<++++++[>--------<-]+<<<]>.>>[
+        [-]<[>+<-]>>[<<+>+>-]<[>+<-[>+<-[>+<-[>+<-[>+<-[>+<-
+            [>+<-[>+<-[>+<-[>[-]>+>+<<<-[>+<-]]]]]]]]]]]+>>>
+    ]<<<
+]
+
+This program doesn't terminate; you will have to kill it.
+Daniel B Cristofani (cristofdathevanetdotcom)
+http://www.hevanet.com/cristofd/brainfuck/