Pythonic way to check if a package is installed or not

Question

Pythonic way to check list of packages installed in Centos/Redhat?

In a bash script, I'd do:

 rpm -qa | grep -w packagename

Answer 1

import sys
import rpm

ts = rpm.TransactionSet()
mi = ts.dbMatch( 'name', sys.argv[1] )
try :
    h = mi.next()
    print "%s-%s-%s" % (h['name'], h['version'], h['release'])
except StopIteration:
    print "Package not found"

1. TransactionSet() will open the RPM database
2. dbMatch with no paramters will set up a match iterator to go over the entire set of installed packages, you can call next on the match iterator to get the next entry, a header object that represents one package

3. dbMatch can also be used to query specific packages, you need to pass the name of a tag, as well as the value for that tag that you are looking for:

   dbMatch('name','mysql')
   

Answer 2

you can use Subprocess:

import subprocess
child = subprocess.Popen("rpm -qa | grep -w packagename", stdout=subprocess.PIPE, shell=True)
output = child.communicate()[0]
print output

using os:

import os
os.system("rpm -qa | grep -w packagename")

Answer 3

import os

present=0
notpresent=0
f3=open('INSTALLED.log','w')
f2=open('NOTINSTALLED.log','w')

f1=open('installed_packagelist.log','w')

var = os.popen("rpm -qa --queryformat '[%{NAME}\n]'").read()
f1.write(var)


lines = [line.rstrip('\n') for line in open('installed_packagelist.log')]

for index in range(len(lines)):
 contents = lines[index]
 test_str = "rpm -V " + contents
 var = os.system(test_str)
 if (var == 0):
  print contents + "file present"
  present = present +1
  f3.write(contents)

 else:
  print contents + "file not present"
  notpresent = notpresent + 1
  f2.write(contents)  

print present
print notpresent

f2.close()
f3.close()

f3=open('INSTALLED.log','r')
f2=open('NOTINSTALLED.log','r')


data=f3.read()
print data

print       "+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"

data=f2.read()
print data

Answer 4

I could not get this answer: https://stackoverflow.com/a/51258124/498657 to work on Python 3.6.8, what did work for me was:

import sys
import rpm

ts = rpm.TransactionSet()
mi = ts.dbMatch( 'name', 'lsof' )

rpmhit=0
for h in mi:
    if h['name'] == 'lsof':
        rpmhit=1
        break

if rpmhit == 0:
    print('Error: Package lsof not installed. Install using: dnf install lsof')
    sys.exit(3)