How to implement bash oneliner into Python3 code?-CodePudding

I have bash oneliner and I can't use implement it into python3 and running it on Rhel server.

 for i in {5000..10000}; do if grep "no such user" <(id $i 2>&1 ) > /dev/null; then echo $i ; break ; fi; done

I've already tried

print(subprocess.check_output('bash -c "for i in {5000..10000}; do if grep "no such user" <(id $i 2>&1 ) > /dev/null; then echo $i ; break ; fi ; done" ', shell=True).decode())

and this

p1 = Popen(["for i in {5000..10000}; do if grep "no such user" <(id $i 2>&1 ) > /dev/null; then echo $i ; break ; fi; done"], stdout=PIPE)

print p1.communicate()

Tried also this

command = '''
    for i in {5000..10000}
do
    if grep "no such user" <(id $i 2>&1 ) > /dev/null
    then echo $i
    break
    fi
done
'''
        uid = subprocess.run(command, capture_output=True, shell=True)

And I always get SyntaxError: invalid syntax or

CompletedProcess(args='\n    for i in {5000..10000}\ndo\n    if grep "no such user" <(id $i 2>&1 ) > /dev/null\n    then echo $i\n    break\n    fi\ndone\n', returncode=1, stdout=b'', stderr=b'/bin/sh: -c: line 3: syntax error near unexpected token `(\'\n/bin/sh: -c: line 3: `    if grep "no such user" <(id $i 2>&1 ) > /dev/null\'\n')

Can you please help me and say what am I doing wrong? I've lost countless hours of debugging it and hope on your help.

CodePudding user response：

While the better answer is to do this all in Python (which will be vastly more efficient), there's no reason you can't do it with a subprocess.

Use a triple-quoted raw string so your bash code is stored in a Python string without anything munging it:

#!/usr/bin/env python
import subprocess

bash_code=r'''
for i in {5000..10000}; do if grep "no such user" <(id "$i" 2>&1 ) > /dev/null; then echo "$i" ; break ; fi; done
'''
p = subprocess.run(['bash', '-c', bash_code], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
print(f"stdout is: {f.stdout}")

CodePudding user response：

Do the loop and output checking in Python.

for i in range(5000, 10001):
    output = subprocess.check_output(['id', str(i)], stderr=subprocess.DEVNULL, encoding='utf-8')
    if 'no such user' in output:
        print(i)
        break

Python also has a pwd module for searching the user database.

from pwd import getpwuid

for i in range(5000, 10001):
    try:
        getpwuid(i)
    except KeyError:
        print(i)
        break