Develop Reference

How to save code at the python prompt in the terminal to a local file

I have just written a bunch of lines of code on the Python prompt at the terminal. Now, I want to save all those lines of code to a .py file.
I am unable to find out how to do that. The only thing that I could find on StackOverflow was this answer but it shows only how to do it in an iPython notebook. I am not using an iPython notebook. I am running the code at the command line on the terminal.
I tried to follow that answer (because just in case) and ran the %save magic command on the terminal but it gave a SyntaxError.
So, how do save it?
Thanks!

See http://blog.e-shell.org/174 . As wu explains, the python prompt is using readline, and you can import a Python library to access this.
>>> import readline
>>> readline.write_history_file('/path/to/history.txt')

You can trying using another interpreter : bpython , I belive it has what you need,check it out.
Save the code you've entered to a file.

You seem to be affected by the misconception, that the python environment is workspace-centered (similar to what I know from Smalltalk and some LISP variants):
fire up with an initial workspace
modify by your liking
store the result
This is unfortunately not the case. While you can import existing files, the other option is to specify an existing file as initially to be loaded and keep the interpreter open by using the -i option.

It really depends on your terminal for the exact commands.
The general idea is to copy everything (if possible) or one page at a time from the terminal into a text editor and then clean the >>> prompts (and possibly other formatting problems) in the text editor.
But anyway, typing a lot of commands directly in the execution environment if really bad practice. At least you test a handful of lines and immediately save them in a file. IDLE is great at this game...

One-word-command from .py (without aliases)

Some programs can be executed from anywhere with a single one-word command. An example of this is youtube-dl, which is a python program that can be executed with the simple command youtube-dl [input]. As far as I have understood, this is simply because there exists a file called /usr/bin/youtube-dl, and /usr/bin is in PATH. However, I do not understand what I have to do to make something like this myself. Right now, I have a python project called testproject that includes a python program like this:
~/testproject/files/myownprogram.py
What do I have to do to make this a binary executable such as youtube-dl?
I know I can make an alias mop="python ~/testproject/files/myownprogram.py", and this is also what I have done, and it works fine. That is, I can write $ mop, and successfully run my program.
But for curiosity's, and learning's, sake, I want to know how to make a file such as the /usr/bin/youtube-dl file, removing the need for aliases.
I find this hard to find information about in search engines...
Any help is greatly appreciated! :-)
Edit:
My question differs from the one marked as duplicate, in that I'm not looking to execute it as a .sh-script. I simply want to execute it as a suffix-less one-word command, similar to all the other executables that are in /usr/bin. :-)
Ex.: $ myown should run my program, without the need for aliases or writing ".sh" or ".py" at the prompt. That is, I want to have a file /usr/bin/myown that somehow runs my testproject at the simple command myownfrom anywhere.

The applications are being executed "from anywhere" because the system has a specific hierarchy of places it looks for these files (the current directory, then the system path). So, it knows to look in /usr/bin because that's in your system path.
As to ensuring it to use python when it's executed, you should add the following to the top of the file (check out some python application source code and you'll see this):
#!/usr/bin/env python
This tells the system to execute the script using the systems "python" command.

Problems installing IDLE2HTML

I'm trying to install IDLE2HTML from the following link in order to print from IDLE in color. I use Python 2.7 on a Mac.
I follow the instructions from the readme.txt, but when I reload IDLE nothing has changed. I don't have the Save As HTML option.
In the past I've installed and reinstalled Python a few times.
When trying to find my idlelib folder (as written in the readme instructions), I eventually found it under the path /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
Is my problem that my python is in /System/Library/?
Any ideas please?

I have not tried this extension, but the following may help. When you start Idle, select File / Path browser on the menu. You should see
_ sys.path
|
+ some_path/pythonxy/Lib/idlelib
|
+ some_path/python27.zip # or MAC equivalent
The first path tells you where the new files should be. If you click the +, you will see what file are there. What about IDLE2HTML.py? The next issue is whether you properly edited config-extensions.def. If you wait a few days for 2.7.9 and install it, you can try the new Options / Config-extensions dialog on the menu. That will show whether Idle can read the new information in the .def file. Or you can edit your question, paste in the new material you added, and comment on this answer, and I will take a look. However, given that the extension has been around for years, I presume that the addition in config-extensions.txt is correct.
I suspect that whenever you upgrade Python, config-extension.def will be overwritten and you will have to re-edit it.

If the problem is not a configuration problem with the IDLE2HTML Python IDLE extension like this answer (for the same question) explains about, it may be a problem with the code itself (this has happened with Python 3 IDLE). This can be checked by running IDLE using the Python file that starts it (<PYTHON LIBRARY DIR>\idlelib\idle.py where <PYTHON LIBRARY DIR> is the location of the standard library for the Python installation), in a command line interpreter (use <PYTHON EXECUTABLE DIR>\python.exe where <PYTHON EXECUTABLE DIR is the location of the executable files that start Python). It will launch IDLE and show any errors in the C.L.I..
Quote from Python idlelib module docstring:
Idle includes an interactive shell and editor. Use the files named idle.* to start Idle.
IDLE2HTML real error example:
A common problem is that IDLE2HTML version 2.0 (latest at time of writing) needs a simple code tweak to work with Python 3.x (a fixed version that works as part of the IDLEX Python module had this tweak). File comparison image (left is original file, right is IDLEX version in image); if the Python version is Python 3.x, import Tkinter needs to be changed to import tkinter as Tkinter and import tkFileDialog needs to be changed to import tkinter.filedialog as tkFileDialog:

Edwards suggestion of using the CLI for diagnosis was very useful. It exposed that the cgi.escape attribute does not exist for Python 3.
I changed the IDLE2HTML.py line 74 from "out.append(cgi.escape(content))" to
"out.append(content)" and after a re-boot it all worked!
Later: well almost... better to replace "import cgi" with "import html and then cgi.escape() with html.escape()
If using Win10 you will need super-admin rights to change IDLE2HTML.

Python script gives `: No such file or directory`

I have several python scripts which work just fine but one script has (as of this morning) started giving me this error if I try to run it from the bash:
: No such file or directory
I am able to run the 'broken' script by doing python script_name.py and after looking around a bit the general idea that I picked up was that maybe my line ending of the hashbang got changed (silently) so I looked at the line ending of a working script and a broken script via the :set list option in VI as indicated in this question -> View line-endings in a text file
Both files appear to end using the same character (a $) so I am kind of at a loss on how to proceed from here. Specifically, how to actually 'see' the line ending in case the set list was not the right method.
PS: The script is executable and the shebang is in there, I stated that it's just this 1 script that was working fine before the weekend but it started giving me this error as of this morning.
-- edit: --
Running the script through dos2unix does get it working again but I would like to know of any way to visualize the line ending somehow in VI(M) or why Geany somehow converted the line endings in the first place (as I never work on a dos/windows system anyhow).

From the comments above it looks like you have dos line endings, and so the hashbang line is not properly processed.
Line ending style are not shown with :set list in Vim because that option is only used when reading/writing the file. In memory line endings are always that, line-endings. The line ending style used for a file is kept in a Vim per-file option, weirdly called fileformat.
To see/change the line ending style from Vim, you can use the following commands:
:set fileformat
:set ff
It will show dos or unix. You want unix, of course ;-).
To change it quickly you can save the file with:
:w ++ff=unix
Or if you prefer:
:set ff=unix
And then save the file normally.
So see all the gory details just do :help fileformat, :help file-formats and :help fileformats

You can also use the dos2unix command to convert the file format
dos2unix
This helped me to run the python scripts
This normally happens when we open files in windows do changes and save it.
if you open the file locate the ^M characters at the end of every line
Thanks

Personally, I find it kinda wrong using direct path to python interpreter. As you dont use windows platform, you should have program env, usually in /usr/bin (/usr/bin/env). Try using following shebang:
#!/usr/bin/env python
Different distros store python binary in /bin or /usr/bin (or some weird locations), and this one makes your script config-independent (as far as possible, here we have possibility that env is stored elsewhere; still - it is less possible that env is not in /usr/bin than that python is mislocated).
I had similiar problem (if not exactly the same) and that worked for me.
Also, I have both python interpreters (2.7.x and 3.x) installed, so I need to use "python3" argument for env. AFAIR usually distros link different names to different binaries, so "env python" will run python2.7 on my system, "env python3" (also python33, or smth like that) will run p3k, and "env python2" (also python27, etc) will run python 2.7.x. Declaring which version of interpreter should be used seems like a good idea too.

I came across this problem editing my code on Windows, checking it in with git, and checking out and running it on Linux.
My solution was: tell git to Do The Right Thing. I issued this command on the Windows box:
git config --global core.autocrlf true
Modified the files and checked them in; voila, no such problem any more.
As discussed on the Git documentation.

Default working directory for Python IDLE?

Is there a configuration file where I can set its default working directory? It currently defaults to my home directory, but I want to set it to another directory when it starts. I know I can do "import os" followed by "os.chdir("")" but that's kind of troublesome. It'd be great if there is a conf file that I can edit and change that setting, but I am unable to find it.
In particular, I've looked into my OS (Ubuntu)'s desktop entry '/usr/share/applications/idle-python3.2.desktop', which doesn't contain a conf file, but points to '/usr/lib/python3.2/idlelib/PyShell.py', which points to config-*.def conf files under the same folder, with 'config-main.def' being the most likely candidate. However I am unable to find where the default path is specified or how it can be changed.
It seems that the path is hard-coded in PyShell.py, though I could be wrong with my limited knowledge on Python. I will keep looking, but would appreciate it if somebody knows the answer on top of his or her head. Thanks in advance.

I actually just discovered the easiest answer, if you use the shortcut link labeled "IDLE (Python GUI)". This is in Windows Vista, so I don't know if it'll work in other OS's.
1) Right-click "Properties".
2) Select "Shortcut" tab.
3) In "Start In", write file path (e.g. "C:\Users...").
This is also my answer here: Default save path for Python IDLE? Let me know if this works!

I've found a solution after looking into PyShell.py:
Create a python file under a preferred directory, in my case '~/.idlerc/init.py', and copy/paste the following lines:
import os
os.chdir('<your preferred directory>')
Pass "-r '~/.idlerc/init.py' " argument to the IDLE startup command, like the following (your exec location and name may vary depending on OS, etc):
/usr/bin/idle-python3.2 -n -r ~/.idlerc/init.py

Just use a shell script such as:
#!/bin/bash
cd /Users/pu/Projects/L-Python
/usr/bin/idle
and run that instead of stock idle. The example is on OS X, adapt to your system.

I'm new to python and learning from 'Dive into Python' by mark Pilgrim (can be found online free)
the answer is in chapter 2.4 - hope he doesn't mind me pasting it here as its also plugging his book and is in the GPL
Before you go any further, I want to briefly mention the library
search path. Python looks in several places when you try to import a
module. Specifically, it looks in all the directories defined in
sys.path. This is just a list, and you can easily view it or modify it
with standard list methods. (You'll learn more about lists later in
this chapter.)
Example 2.4. Import Search Path
import sys
sys.path
sys.path.append('/my/new/path')
It's a good book I am a programmer - usually I find learning from books sends me quickly to sleep - not the case here ....

All I had to do here (Linux Mint 18.2 Xfce) ...
Just add path in line "working directory" = "Arbeitsverzeichnis"

It can change depending on where you installed Python. Open up IDLE, import os, then call os.getcwd() and that should tell you exactly where your IDLE is working on.

One default path is specified in idlelib.IOBinding.IOBinding.dirname or idlelib.IOBinding.IOBinding.filename
Ubuntu
So my idle-python3.desktop
file in /usr/share/applications looks like this:
[Desktop Entry]
Name=IDLE (using Python-3)
Comment=Integrated Development Environment for Python (using Python-3)
Exec=python3 -c "import idlelib.IOBinding, os; idlelib.IOBinding.IOBinding.dirname='/DEFAULT/DIRECTORY';import idlelib.idle"
Icon=/usr/share/pixmaps/python3.xpm
Terminal=false
Type=Application
Categories=Application;Development;
StartupNotify=true
To use it you need to set /DEFAULT/DIRECTORY to your desired directory, copy it with root rights into /usr/share/applications. You can also use it for Python 2 but then you need to replace the 3s with 2s.
ConfigFiles
There are also extensions that can be loaded. These must be modules and you specify them by module name. The config files for IDLE are located in HOME/.idlerc and parsed with a configparser. I did not get further with this.

Here's a way to reset IDLE's default working directory for MacOS if you launch Idle as an application by double-clicking it. You need a different solution if you launch Idle from a command line in Terminal. This solution is a permanent fix. You don't have to rechange the directory everytime you launch IDLE. I wish it were easier.
The idea is to edit a resource file inside of the IDLE package in Applications.
Start by finding the the file. In Finder, go to IDLE in Applications (in the Python folder) as if you wanted to open it. Right click and select "show package contents". Open Contents, then open Resources. In Resources, you'll see a file called idlemain.py. This file executes when you launch idle and sets, among other things, the working directory. We're going to edit that.
But before you can edit it, you need to give yourself permission to write to it. To do that, right click on the idlemain.py and select get info. Scroll to the bottom of the getinfo window and you'll see the Sharing & Permissions section. On the bottom right there's a lock icom. Click the lock and follow the prompts to unlock it. Once it's unlocked, look to the left for the + (under the list of users with permissions). Click it. That will bring up a window with a list of users you can add. Select yourself (probably the name of your computer or your user account) and click Select. You'll see yourself added to the list of names with permissions. Click where is says "Read only" next to your name and change it to "Read & Write". Be careful not to change anything else. When you're done, click the lock again to lock the changes.
Now go back to idlemain.py and open it with any text editor (you could use Idle, TextEdit, or anything. Right under the import statement at the top is the code to change the default working directory. Read the comment if you like, then replace the single line of code under the comment with
os.chdir('path of your desired working directory')
Mine looks like this:
os.chdir('/Users/MyName/Documents/Python')
Save your changes (which should work because you gave yourself permission). Next time you start Idle, you should be in your desired working directory. You can check with the following commands:
import os
os.getcwd()

This ought to be the number one answer. I have been playing around this for an hour or more and nothing worked. Paul explains this perfectly. It's just like the PATH statement in Windows. I successfully imported a module by appending my personal "PythonModules" path/dir on my Mac (starting at "/users/etc") using a simple
import xxxx command in Idle.