Run-time Information

Your app should run in a bundle exactly as it does when run from source. However, you may want to learn at run-time whether the app is running from source or whether it is bundled (“frozen”). You can use the following code to check “are we bundled?”:

import sys
if getattr(sys, 'frozen', False) and hasattr(sys, '_MEIPASS'):
    print('running in a PyInstaller bundle')
    print('running in a normal Python process')

When a bundled app starts up, the bootloader sets the sys.frozen attribute and stores the absolute path to the bundle folder in sys._MEIPASS. For a one-folder bundle, this is the path to that folder. For a one-file bundle, this is the path to the temporary folder created by the bootloader (see How the One-File Program Works).

When your app is running, it may need to access data files in one of the following locations:

  • Files that were bundled with it (see Adding Data Files).

  • Files the user has placed with the app bundle, say in the same folder.

  • Files in the user’s current working directory.

The program has access to several variables for these uses.

Using __file__

When your program is not bundled, the Python variable __file__ refers to the current path of the module it is contained in. When importing a module from a bundled script, the PyInstaller bootloader will set the module’s __file__ attribute to the correct path relative to the bundle folder.

For example, if you import mypackage.mymodule from a bundled script, then the __file__ attribute of that module will be sys._MEIPASS + 'mypackage/mymodule.pyc'. So if you have a data file at mypackage/file.dat that you added to the bundle at mypackage/file.dat, the following code will get its path (in both the non-bundled and the bundled case):

from os import path
path_to_dat = path.abspath(path.join(path.dirname(__file__), 'file.dat'))

In the main script (the __main__ module) itself, the __file__ variable contains path to the script file. In Python 3.8 and earlier, this path is either absolute or relative (depending on how the script was passed to the python interpreter), while in Python 3.9 and later, it is always an absolute path. In the bundled script, the PyInstaller bootloader always sets the __file__ variable inside the __main__ module to the absolute path inside the bundle directory, as if the byte-compiled entry-point script existed there.

For example, if your entry-point script is called, then the __file__ attribute inside the bundled script will point to sys._MEIPASS + ''. Therefore, locating a data file relative to the main script can be either done directly using sys._MEIPASS or via the parent path of the __file__ inside the main script.

The following example will get the path to a file other-file.dat located next to the main script if not bundled and inside the bundle folder if it is bundled:

from os import path
bundle_dir = path.abspath(path.dirname(__file__))
path_to_dat = path.join(bundle_dir, 'other-file.dat')

Or, if you’d rather use pathlib:

from pathlib import Path
bundle_dir = Path(__file__).parent
path_to_dat = Path.cwd() / bundle_dir / "other-file.dat"

Changed in version 5.0: Formerly, the __file__ attribute of the entry-point script (the __main__ module) was set to only its basename rather than its full (absolute or relative) path within the bundle directory. Therefore, PyInstaller documentation used to suggest sys._MEIPASS as means for locating resources relative to the bundled entry-point script. Now, __file__ is always set to the absolute full path, and is the preferred way of locating such resources.

Placing data files at expected locations inside the bundle

To place the data-files where your code expects them to be (i.e., relative to the main script or bundle directory), you can use the dest parameter of the --add-data=source:dest command-line switches. Assuming you normally use the following code in a file named to locate a file file.dat in the same folder:

from os import path
path_to_dat = path.abspath(path.join(path.dirname(__file__), 'file.dat'))

Or the pathlib equivalent:

from pathlib import Path
path_to_dat = (Path.cwd() / __file__).with_name("file.dat")

And is not part of a package (not in a folder containing an, then __file__ will be [app root]/my_script.pyc meaning that if you put file.dat in the root of your package, using:

PyInstaller --add-data=/path/to/file.dat:.

It will be found correctly at runtime without changing


Windows users should use ; instead of : in the above line.

If __file__ is checked from inside a package or library (say then __file__ will be [app root]/my_library/data.pyc and --add-data should mirror that:

PyInstaller --add-data=/path/to/my_library/file.dat:./my_library

However, in this case it is much easier to switch to the spec file and use the collect_data_files() helper function:

from PyInstaller.utils.hooks import collect_data_files

a = Analysis(...,

Using sys.executable and sys.argv[0]

When a normal Python script runs, sys.executable is the path to the program that was executed, namely, the Python interpreter. In a frozen app, sys.executable is also the path to the program that was executed, but that is not Python; it is the bootloader in either the one-file app or the executable in the one-folder app. This gives you a reliable way to locate the frozen executable the user actually launched.

The value of sys.argv[0] is the name or relative path that was used in the user’s command. It may be a relative path or an absolute path depending on the platform and how the app was launched.

If the user launches the app by way of a symbolic link, sys.argv[0] uses that symbolic name, while sys.executable is the actual path to the executable. Sometimes the same app is linked under different names and is expected to behave differently depending on the name that is used to launch it. For this case, you would test os.path.basename(sys.argv[0])

On the other hand, sometimes the user is told to store the executable in the same folder as the files it will operate on, for example a music player that should be stored in the same folder as the audio files it will play. For this case, you would use os.path.dirname(sys.executable).

The following small program explores some of these possibilities. Save it as Execute it as a Python script, then bundled as a one-folder app. Then bundle it as a one-file app and launch it directly and also via a symbolic link:

import sys, os
frozen = 'not'
if getattr(sys, 'frozen', False):
        # we are running in a bundle
        frozen = 'ever so'
        bundle_dir = sys._MEIPASS
        # we are running in a normal Python environment
        bundle_dir = os.path.dirname(os.path.abspath(__file__))
print( 'we are',frozen,'frozen')
print( 'bundle dir is', bundle_dir )
print( 'sys.argv[0] is', sys.argv[0] )
print( 'sys.executable is', sys.executable )
print( 'os.getcwd is', os.getcwd() )

LD_LIBRARY_PATH / LIBPATH considerations

This environment variable is used to discover libraries, it is the library search path - on GNU/Linux and *BSD LD_LIBRARY_PATH is used, on AIX it is LIBPATH.

If it exists, PyInstaller saves the original value to *_ORIG, then modifies the search path so that the bundled libraries are found first by the bundled code.

But if your code executes a system program, you often do not want that this system program loads your bundled libraries (that are maybe not compatible with your system program) - it rather should load the correct libraries from the system locations like it usually does.

Thus you need to restore the original path before creating the subprocess with the system program.

env = dict(os.environ)  # make a copy of the environment
lp_key = 'LD_LIBRARY_PATH'  # for GNU/Linux and *BSD.
lp_orig = env.get(lp_key + '_ORIG')
if lp_orig is not None:
    env[lp_key] = lp_orig  # restore the original, unmodified value
    # This happens when LD_LIBRARY_PATH was not set.
    # Remove the env var as a last resort:
    env.pop(lp_key, None)
p = Popen(system_cmd, ..., env=env)  # create the process