Linux path to python interpreter

Find full path of the Python interpreter?

How do I find the full path of the currently running Python interpreter from within the currently executing Python script?

3 Answers 3

sys.executable contains full path of the currently running Python interpreter.

import sys print(sys.executable) 

This does not seem to work from scripts with a shebang /usr/bin/env python executed as env -i ./script . In that case it returns the current working directory.

@JohnFreeman: I tried this on a GNU/Linux box w/ GNU coreutils 8.4 (env) and Python 3.4.2. #!/usr/bin/env python3 will return the correct full binary path via sys.executable . Perhaps your OS or Python version behaves slightly differently.

Note that this will not return the name of the Python interpreter if Python is embedded in some application.

I tried this with the shebang for python2 and python3 and it printed the correct executable. I also tried with no shebang and called the script with the python and python3 commands and it printed the correct executable.

@mic_e, this may have been true in 2015, but I just tried it today and it behaves as expected (it returns the absolute file of the executable that embeds Python).

Just noting a different way of questionable usefulness, using os.environ :

import os python_executable_path = os.environ['_'] 

$ python -c "import os; print(os.environ['_'])" /usr/bin/python 

There are a few alternate ways to figure out the currently used python in Linux is:

Similarly On Windows with Cygwin will also result the same.

kuvivek@HOSTNAME ~ $ which python /usr/bin/python kuvivek@HOSTNAME ~ $ whereis python python: /usr/bin/python /usr/bin/python3.4 /usr/lib/python2.7 /usr/lib/python3.4 /usr/include/python2.7 /usr/include/python3.4m /usr/share/man/man1/python.1.gz kuvivek@HOSTNAME ~ $ which python3 /usr/bin/python3 kuvivek@HOSTNAME ~ $ command -v python /usr/bin/python kuvivek@HOSTNAME ~ $ type python python is hashed (/usr/bin/python) 

If you are already in the python shell. Try anyone of these. Note: This is an alternate way. Not the best pythonic way.

>>> import os >>> os.popen('which python').read() '/usr/bin/python\n' >>> >>> os.popen('type python').read() 'python is /usr/bin/python\n' >>> >>> os.popen('command -v python').read() '/usr/bin/python\n' >>> >>> 

If you are not sure of the actual path of the python command and is available in your system, Use the following command.

pi@osboxes:~ $ which python /usr/bin/python pi@osboxes:~ $ readlink -f $(which python) /usr/bin/python2.7 pi@osboxes:~ $ pi@osboxes:~ $ which python3 /usr/bin/python3 pi@osboxes:~ $ pi@osboxes:~ $ readlink -f $(which python3) /usr/bin/python3.7 pi@osboxes:~ $ 

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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.

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2. Using Python on Unix platforms¶

2.1. Getting and installing the latest version of Python¶

2.1.1. On Linux¶

Python comes preinstalled on most Linux distributions, and is available as a package on all others. However there are certain features you might want to use that are not available on your distro’s package. You can easily compile the latest version of Python from source.

In the event that Python doesn’t come preinstalled and isn’t in the repositories as well, you can easily make packages for your own distro. Have a look at the following links:

2.1.2. On FreeBSD and OpenBSD¶

pkg_add -r python pkg_add ftp://ftp.openbsd.org/pub/OpenBSD/4.2/packages//python-.tgz

pkg_add ftp://ftp.openbsd.org/pub/OpenBSD/4.2/packages/i386/python-2.5.1p2.tgz

2.1.3. On OpenSolaris¶

You can get Python from OpenCSW. Various versions of Python are available and can be installed with e.g. pkgutil -i python27 .

2.2. Building Python¶

If you want to compile CPython yourself, first thing you should do is get the source. You can download either the latest release’s source or just grab a fresh clone. (If you want to contribute patches, you will need a clone.)

The build process consists of the usual commands:

./configure make make install

Configuration options and caveats for specific Unix platforms are extensively documented in the README.rst file in the root of the Python source tree.

make install can overwrite or masquerade the python3 binary. make altinstall is therefore recommended instead of make install since it only installs exec_prefix /bin/python version .

2.3. Python-related paths and files¶

These are subject to difference depending on local installation conventions; prefix and exec_prefix are installation-dependent and should be interpreted as for GNU software; they may be the same.

For example, on most Linux systems, the default for both is /usr .

Recommended location of the interpreter.

prefix /lib/python version , exec_prefix /lib/python version

Recommended locations of the directories containing the standard modules.

prefix /include/python version , exec_prefix /include/python version

Recommended locations of the directories containing the include files needed for developing Python extensions and embedding the interpreter.

2.4. Miscellaneous¶

To easily use Python scripts on Unix, you need to make them executable, e.g. with

and put an appropriate Shebang line at the top of the script. A good choice is usually

which searches for the Python interpreter in the whole PATH . However, some Unices may not have the env command, so you may need to hardcode /usr/bin/python3 as the interpreter path.

To use shell commands in your Python scripts, look at the subprocess module.

2.5. Custom OpenSSL¶

1. To use your vendor’s OpenSSL configuration and system trust store, locate the directory with openssl.cnf file or symlink in /etc . On most distribution the file is either in /etc/ssl or /etc/pki/tls . The directory should also contain a cert.pem file and/or a certs directory.

$ find /etc/ -name openssl.cnf -printf "%h\n" /etc/ssl 

$ curl -O https://www.openssl.org/source/openssl-VERSION.tar.gz $ tar xzf openssl-VERSION $ pushd openssl-VERSION $ ./config \ --prefix=/usr/local/custom-openssl \ --libdir=lib \ --openssldir=/etc/ssl $ make -j1 depend $ make -j8 $ make install_sw $ popd 

$ pushd python-3.x.x $ ./configure -C \ --with-openssl=/usr/local/custom-openssl \ --with-openssl-rpath=auto \ --prefix=/usr/local/python-3.x.x $ make -j8 $ make altinstall

Patch releases of OpenSSL have a backwards compatible ABI. You don’t need to recompile Python to update OpenSSL. It’s sufficient to replace the custom OpenSSL installation with a newer version.

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