Check if a Debian package is installed from Python

Question

Is there an elegant and more Python-like way to check if a package is installed on Debian?

In a bash script, I\'d do:

dpkg -s packagename | grep Stat         


        

Answer 1

This is a pythonic way:

import apt
cache = apt.Cache()
if cache['package-name'].is_installed:
    print "YES it's installed"
else:
    print "NO it's NOT installed"

Answer 2

If you are checking for the existence of a package that installs a Python module, you can test for this from within a dependent Python script - try to import it and see if you get an exception:

import sys
try:
    import maybe
except ImportError:
    print "Sorry, must install the maybe package to run this program."
    sys.exit(1)

Answer 3

Inspired by the previous answers, this works nicely for both Python 2 and Python 3 and avoids try/catch for the key error:

import apt
package = 'foo' # insert your package name here
cache = apt.Cache()
package_installed = False

if package in cache:
    package_installed = cache[package].is_installed

Answer 4

This is some code that would give you a neat way to display if the package is installed or not (without triggering a messy error message on the screen). This works in Python 3 only, though.

import apt
cache = apt.Cache()
cache.open()

response = "Package Installed."
try:
    cache['notapkg'].is_installed
except KeyError:
    response = "Package Not Installed."

print(response)

Answer 5

I needed a cross-platform compatible solution so I ended up using which.

import subprocess
retval = subprocess.call(["which", "packagename"])
if retval != 0:
    print("Packagename not installed!")

Although it's not as pythonic as the above answers it does work on most platforms.

Answer 6

A slightly nicer, hopefully idiomatic version of your bash example:

import os, subprocess
devnull = open(os.devnull,"w")
retval = subprocess.call(["dpkg","-s","coreutils"],stdout=devnull,stderr=subprocess.STDOUT)
devnull.close()
if retval != 0:
    print "Package coreutils not installed."