Check if program is installed python

checking if program is installing using python

However, I didn’t see the original posting for this thread so I’m not
sure if this is what is being looked for.

It’s very rare that a program like Word is installed
in the PATH, so it’s unlikely this helps.

Generally you would need to look in the registry, or
perhaps use os.popen() to parse the output of executing
the command «assoc .doc», to do what is required.

It might help for the OP to describe more about what
he plans to do with the information, since there might
be simpler/better approaches.

i want to check to see if a certain program is installed on my
windows box using python. how can i do that. (ie, i want to
see if «word» is installed)

This won’t help you if you’re after an off-the-cuff search for
installed apps, but if you need to determine the existence of a known
application in order to do something specific, this might be of some
use.

First, use the registry to determine the install location of the app.
(You might like to check out the following recipe, which deals with
accessing the registry via Python:
http://aspn.activestate.com/ASPN/Coo. n/Recipe/66011)

For example, to find the location where MS Office 2003 is installed,
you need to check the registry key
«HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\11.0 \Common\InstallRoot»
which has two values, the 2nd of which, «Path» is set to «C:\Program
Files\Microsoft Office\OFFICE11\» on my work PC.

Once you have the location, you can just use
os.path.exists(path-from-reg + «\Word.exe») to check that it’s actually
there.

In some cases, such as with MSOffice, the key you need to refer to will
depend on the version installed. As mentioned, the regkey above is for
MS Office 2003, which is recorded in the registry as version 11.0. If
you’re only concerned that they have an application installed without
caring what version they’re using, you’ll need to check for several
keys to find the information you’re looking for. (Office XP is 10.0,
Office 2K is 9.0, etc) Office is pretty consistent about this between
versions but other applications (such as the godawful virus checker we
use here) can’t be counted on being quite as helpful.

Also worth noting if you’re actually interested in testing for the
existence of Office apps is that each member of the Office suite can
have its own install location. So if you’re only checking for Word, the
key
«HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\11.0 \Word\InstallRoot»
would be more relevant than the common install area given above.

Hopefully something in this somewhere will help 🙂

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Check if program is installed python

Last updated: Feb 23, 2023
Reading time · 3 min

# Table of Contents

# Check if a Python package is installed

To check if a Python package is installed:

1. Import the package in a try block.
2. Use an except block to handle the potential ModuleNotFoundError .
3. If the try block runs successfully, the module is installed.

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try: import requests print('The requests module is installed') except ModuleNotFoundError: print('The requests module is NOT installed') 

We used a try/except block to check if a module is installed.

If the try block doesn’t raise an exception, the module is installed.

If the module isn’t installed, a ModuleNotFoundError error is raised and the except block runs.

# Installing the module if it isn’t already installed

You can also extend the try/except statement to install the module if it isn’t installed.

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import sys import subprocess try: import requests print('The requests module is installed') except ModuleNotFoundError: print('The requests module is NOT installed') # 👇️ optionally install module python = sys.executable subprocess.check_call( [python, '-m', 'pip', 'install', 'requests'], stdout=subprocess.DEVNULL ) finally: import requests 

If you need to check if a package is installed using pip , use the pip show command.

The pip show module_name command will either state that the package is not installed or show a bunch of information about the package, including the location where the package is installed.

You can also use the following one-liner command.

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python -c 'import pkgutil; print(1 if pkgutil.find_loader("module_name") else 0)' 

Make sure to replace module_name with the actual name of the module you are checking for.

The command returns 1 if the module is installed and 0 if it isn’t but this can be easily adjusted.

# Check if a Python package is installed using find_spec

An alternative approach is to use the importlib.util.find_spec method.

The find_spec() method will return a spec object if the module is installed, otherwise, None is returned.

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import importlib.util module_name = 'requests' spec = importlib.util.find_spec(module_name) if spec: print(f'The module_name> module is installed') else: print(f'The module_name> module is NOT installed') 

The importlib.util.find_spec method finds the spec for a module.

The spec for a module is a namespace containing the import-related information used to load the module.

If no spec is found, the method returns None.

# Installing the package if it isn’t already installed

You can optionally install the package if it isn’t already installed.

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import importlib.util import sys import subprocess module_name = 'requests' spec = importlib.util.find_spec(module_name) if spec: print(f'The module_name> module is installed') else: print(f'The module_name> module is NOT installed') # 👇️ optionally install the module if it's not installed python = sys.executable subprocess.check_call( [python, '-m', 'pip', 'install', 'requests'], stdout=subprocess.DEVNULL ) 

# Checking if the module isn’t installed

If you need to check if the module isn’t installed, check if the spec variable stores a None value.

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import importlib.util import sys import subprocess module_name = 'requests' spec = importlib.util.find_spec(module_name) if spec is None: print(f'The module_name> module is NOT installed') # 👇️ optionally install the module if it's not installed python = sys.executable subprocess.check_call( [python, '-m', 'pip', 'install', 'requests'], stdout=subprocess.DEVNULL ) print(f'The module_name> module is now installed') 

Which approach you pick is a matter of personal preference. I’d use the try/except statement because I find it quite direct and easy to read.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

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Check if Python Package is installed

Sometimes when we need to use certain modules in our program, we forget whether we have it installed in our system or not. We can directly do this by importing the required module in our code but it will raise an «ImportError» which is not something that we desire.

We can also use python’s command line tool but that won’t help us to check our required package in our script.

Methods to Check if Python Package is Installed

There are many ways in which we can check our packages in python. Let us look at some of the easy ways in which we can make sure all our packages are available in our system before use.

Method 1: Using the importlib.util and sys modules

To check whether we have a specific module or library installed in our system, we can use the python library called importlib.util along with the sys (system) module.

The import library or the importlib module contains a function called find_spec() which is a shorter version of finding a specific module. The syntax of the function is

importlib.util.find_spec(filename or modulename, path(optional), target=None)

Let us take a look at how this can be done.

In my system I already have the numerical python or the numpy module installed. Hence for this example, I will check whether my code can correctly judge whether the module is present or not.

As for your need, please feel free to change the name of the module as per your requirements.

#importing importlib.util module import importlib.util #importing the system module import sys # For illustration name = 'numpy' #code to check if the library exists if (spec := importlib.util.find_spec(name)) is not None: #displaying that the module is found print(f" already in sys.modules") #importing the present module module = importlib.util.module_from_spec(spec) sys.modules[name] = module spec.loader.exec_module(module) #displaying that the module has been imported print(f" has been imported") #else displaying that the module is absent else: print(f"can't find the module")

'numpy' already in sys.modules 'numpy' has been imported

Method 2: By using the os module

The os module can also be used to determine whether a particular library exists or not in our system. Let’s take a look at the same.

#importing the os module import os #opening the module list lst = os.popen('pip list') #storing the list of pip modules pack_list = lst.read() #formatting of the list Detpack=list(pack_list.split(" ")) # setting counter c = 0 for i in Detpack: if "numpy" in i: c = 1 break # Checking the value of counter if c==1: print("Yay! Module is Installed") else : print("Uh oh! Module is not installed")

Since in this code I am also checking the availability of numpy in my computer, the output should be the same as the previous example. The output is given below.

Method 3: Exception Handling

This is the easiest method to check whether a package is installed or not. In this method we will use python’s built-in exception handling by using the try-except block. The try-except block just like its name suggests tries to perform an action defined by the user. When the execution of the user defined code in the try block fails, the except block handles it without the hassle of raising an error or an exception.

Lets look at how exception handling works in python. For this example, let’s use a library that I don’t have installed in my system, called, emoji. This is to check if the except condition handles error properly or not. Again feel free to change the name of the modules as per your wish.

try: #trying to import emoji import emoji print("Module Already installed") #handling exception if file not found except ImportError as err: print("Error>>", err)

The output of the above code would be:

Error>> No module named 'emoji'

Note: To read about exception handling in python, read this awesome and thorough article on askpython!

List of installed packages

The following command line code can be used to get a precise list of all the python packages installed in our system.

The output will list all of the installed python modules in your system just like as shown below.

Summary

Checking whether are packages are properly stored and readily available is a must before importing them in our code. If you are unsure about a particular package installed your system, you can use any of the first three methods. To list all the available packages in your system use the fourth method. We hope you find your solution!

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