Узнать где лежит python linux

2. Using the Python Interpreter¶

The Python interpreter is usually installed as /usr/local/bin/python3.11 on those machines where it is available; putting /usr/local/bin in your Unix shell’s search path makes it possible to start it by typing the command:

to the shell. 1 Since the choice of the directory where the interpreter lives is an installation option, other places are possible; check with your local Python guru or system administrator. (E.g., /usr/local/python is a popular alternative location.)

On Windows machines where you have installed Python from the Microsoft Store , the python3.11 command will be available. If you have the py.exe launcher installed, you can use the py command. See Excursus: Setting environment variables for other ways to launch Python.

Typing an end-of-file character ( Control — D on Unix, Control — Z on Windows) at the primary prompt causes the interpreter to exit with a zero exit status. If that doesn’t work, you can exit the interpreter by typing the following command: quit() .

The interpreter’s line-editing features include interactive editing, history substitution and code completion on systems that support the GNU Readline library. Perhaps the quickest check to see whether command line editing is supported is typing Control — P to the first Python prompt you get. If it beeps, you have command line editing; see Appendix Interactive Input Editing and History Substitution for an introduction to the keys. If nothing appears to happen, or if ^P is echoed, command line editing isn’t available; you’ll only be able to use backspace to remove characters from the current line.

The interpreter operates somewhat like the Unix shell: when called with standard input connected to a tty device, it reads and executes commands interactively; when called with a file name argument or with a file as standard input, it reads and executes a script from that file.

A second way of starting the interpreter is python -c command [arg] . , which executes the statement(s) in command, analogous to the shell’s -c option. Since Python statements often contain spaces or other characters that are special to the shell, it is usually advised to quote command in its entirety.

Some Python modules are also useful as scripts. These can be invoked using python -m module [arg] . , which executes the source file for module as if you had spelled out its full name on the command line.

When a script file is used, it is sometimes useful to be able to run the script and enter interactive mode afterwards. This can be done by passing -i before the script.

All command line options are described in Command line and environment .

2.1.1. Argument Passing¶

When known to the interpreter, the script name and additional arguments thereafter are turned into a list of strings and assigned to the argv variable in the sys module. You can access this list by executing import sys . The length of the list is at least one; when no script and no arguments are given, sys.argv[0] is an empty string. When the script name is given as ‘-‘ (meaning standard input), sys.argv[0] is set to ‘-‘ . When -c command is used, sys.argv[0] is set to ‘-c’ . When -m module is used, sys.argv[0] is set to the full name of the located module. Options found after -c command or -m module are not consumed by the Python interpreter’s option processing but left in sys.argv for the command or module to handle.

2.1.2. Interactive Mode¶

When commands are read from a tty, the interpreter is said to be in interactive mode. In this mode it prompts for the next command with the primary prompt, usually three greater-than signs ( >>> ); for continuation lines it prompts with the secondary prompt, by default three dots ( . ). The interpreter prints a welcome message stating its version number and a copyright notice before printing the first prompt:

$ python3.11 Python 3.11 (default, April 4 2021, 09:25:04) [GCC 10.2.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> 

Continuation lines are needed when entering a multi-line construct. As an example, take a look at this if statement:

>>> the_world_is_flat = True >>> if the_world_is_flat: . print("Be careful not to fall off!") . Be careful not to fall off! 

For more on interactive mode, see Interactive Mode .

2.2. The Interpreter and Its Environment¶

2.2.1. Source Code Encoding¶

By default, Python source files are treated as encoded in UTF-8. In that encoding, characters of most languages in the world can be used simultaneously in string literals, identifiers and comments — although the standard library only uses ASCII characters for identifiers, a convention that any portable code should follow. To display all these characters properly, your editor must recognize that the file is UTF-8, and it must use a font that supports all the characters in the file.

To declare an encoding other than the default one, a special comment line should be added as the first line of the file. The syntax is as follows:

where encoding is one of the valid codecs supported by Python.

For example, to declare that Windows-1252 encoding is to be used, the first line of your source code file should be:

One exception to the first line rule is when the source code starts with a UNIX “shebang” line . In this case, the encoding declaration should be added as the second line of the file. For example:

#!/usr/bin/env python3 # -*- coding: cp1252 -*- 

On Unix, the Python 3.x interpreter is by default not installed with the executable named python , so that it does not conflict with a simultaneously installed Python 2.x executable.

Table of Contents

Источник

How to Find the Python Installation Path on Ubuntu, Debian, or Linux Mint

There comes a time now and again when you might want to know where your Python installation path on your Ubuntu, Debian, or Linux Mint distros is located.

Generally, by default, your Python binary is located at /usr/bin/python but it may not always be a guarantee depending on the version you are using. As you can see from this post you can actually install a different version from the default that comes with your distro.

As with the case with many things on Linux systems, there is more than one way to reliably get the Python installation path on that system.

Getting the Python Installation Path Using PYTHONPATH

You can get the value of PYTHONPATH only if it has been set. This is an environment variable that is available on the system. If it has not been set then the result of running any one of the commands below will not return anything.

If the above commands do not work you can also get the path using the which command as shown below.

$ which python /usr/bin/python

Conclusion

Once you know the path of the default Python installation path for your system you can permanently add it as an environment variable by opening the startup file you use for your default shell. This is usually ~/.profile in Ubuntu.

Open the file in your preferred editor and add the following line at the end of that file.

export PYTHONPATH=/usr/bin/python

You then need to restart your terminal to effect the change. You can also run the above on the command-line if you just need it to last the current session.

Found this article interesting? Follow Brightwhiz on Facebook, Twitter, and YouTube to read and watch more content we post.

Источник

How to get the PYTHONPATH in shell?

sys.path is not PYTHONPATH , sys.path actually consists of multiple things : current dir,PYTHONPATH,standard library, and paths contained in .pth files if any. docs.python.org/2/tutorial/modules.html#the-module-search-path

6 Answers 6

The environment variable PYTHONPATH is actually only added to the list of locations Python searches for modules. You can print out the full list in the terminal like this:

python -c "import sys; print(sys.path)" 

Or if want the output in the UNIX directory list style (separated by : ) you can do this:

python -c "import sys; print(':'.join(x for x in sys.path if x))" 

Which will output something like this:

/usr/local/lib/python2.7/dist-packages/feedparser-5.1.3-py2.7.egg:/usr/local/lib/ python2.7/dist-packages/stripogram-1.5-py2.7.egg:/home/qiime/lib:/home/debian:/us r/lib/python2.7:/usr/lib/python2.7/plat-linux2:/usr/lib/python2.7/lib-tk:/usr/lib /python2.7/lib-old:/usr/lib/python2.7/lib- dynload:/usr/local/lib/python2.7/dist- packages:/usr/lib/python2.7/dist-packages:/usr/lib/python2.7/dist-packages/PIL:/u sr/lib/python2.7/dist-packages/gst-0.10:/usr/lib/python2.7/dist-packages/gtk-2.0: /usr/lib/pymodules/python2.7

@variable No, the paths in PYTHONPATH is added to the paths in sys.path when the Python interpreter starts. In other words, sys.path will include all the paths in PYTHONPATH , but also additional paths, like the path to the Python standard library and the path to installed packages.

This gives me syntax error (pointing to end of import word — EOL while scanning string literal): python -c ‘import os; print(os.environ[«PYTHONPATH»])’. If I use double quote then it says «name ‘PYTHONPATH’ is not defined»

Just write:

just write which python in your terminal and you will see the python path you are using.

That’s the path to the python executable NOT the PYTHONPATH. PYTHONPATH is where python itself looks for modules to import.

Those of us using Python 3.x should do this:

python -c "import sys; print(sys.path)" 

Python, at startup, loads a bunch of values into sys.path (which is «implemented» via a list of strings), including:

• various hardcoded places
• the value of $PYTHONPATH
• probably some stuff from startup files (I’m not sure if Python has rcfiles )

$PYTHONPATH is only one part of the eventual value of sys.path .

If you’re after the value of sys.path , the best way would be to ask Python (thanks @Codemonkey):

python -c "import sys; print sys.path" 

Python 2.x:
python -c «import sys; print ‘\n’.join(sys.path)»

Python 3.x:
python3 -c «import sys; print(‘\n’.join(sys.path))»

The output will be more readable and clean, like so:

/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7 /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload /Library/Python/2.7/site-packages /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC

Источник

Where Is Python Installed

1. Use the dirname() Function to Find the Installation Folder of Python
2. Use the where Command to Find the Installation Folder of Python
3. Use the which Command to Find the Installation Folder of Python

The installation folder of any software or application has some significance since it points us to the exact place where most of the related files and folders related to it can be found. The same goes for Python; we have to install it at a specific location where it stores the language’s modules and basic framework.

In this tutorial, we will learn how to view the path of the installation folder of Python.

Use the dirname() Function to Find the Installation Folder of Python

The os library is used to interact with the Operating System and has functions available to retrieve full paths of the files. The dirname() function from this library can be used to retrieve the directory from the specified file’s path.

To return the installation directory, we pass the sys.executable to this function from the sys library. The sys.executable returns the path of the binary executable of the Python interpreter.

The following code shows how to use this.

import os import sys  print(os.path.dirname(sys.executable)) 

Use the where Command to Find the Installation Folder of Python

We can directly use the where python command in the command prompt to find Python’s installation folder in windows.

C:\>where python C:\Python\Python 3.9\python.exe 

Use the which Command to Find the Installation Folder of Python

In Linux and macOS, we can use the which python command in the terminal to view Python’s installation path.

Источник