CODEWITHSUNDEEP
pythonpython-3.xsubprocess
fightstarr20
fightstarr20

Reputation: 12628

Python 3 loop through subprocess output to search for filename

I am running a terminal command to list a directory, I would like to loop through each line returned and search for a particular filename, I have this so far...

import subprocess

for line in subprocess.check_output(['ls', '-l']):
    if "(myfile.txt)" in line: 
        print("File Found")

But this is just outputing the list and doesn't seem to be searching for the file, anyone have an example they can point me at?

Upvotes: 2

Views: 1255

Answers (5)

Poiz
Poiz

Reputation: 7617

Calling ls from within subprocess would return a Bytes Object.
So, first, You might want to convert the returned value to a String.
And then split the String with New-Line ("\n") as delimiter.
Afterwards, you can iterate and search for your Needle in the List-Values.

import subprocess
# CALLING "subprocess.check_output(['ls', '-l']" RETURNS BYTES OBJECT...
# SO WE DECODE THE BYTES INTO STRING, FIRST
# AND THEN SPLIT AT THE NEW-LINE BOUNDARY TO CONVERT IT TO A LIST
for line in bytes.decode(subprocess.check_output(['ls', '-l'])).split(sep="\n"):
    # NOW WE CAN CHECK IF THE DESIRED FILE IS IN THE LINE
    if "(myfile.txt)" in line:
        print("File Found")

Upvotes: 1

Hai Vu
Hai Vu

Reputation: 40783

Why not use something that is more reliable such as os.listdir or glob:

import glob

if glob.glob('myfile.txt'):
    print('File found')
else:
    print('File not found')

The glob.glob function returns a list of files that match the wildcard. In this case, you will have ['myfile.txt'] if the file exists, or [] if not.

Upvotes: 1

Tai
Tai

Reputation: 8004

You can try to pass in the encoding utf-8 and split it by \n.

for line in subprocess.check_output(['ls', '-l'], encoding="utf-8").split("\n"):
    # print(line)
    if "myfile.txt" in line: 
         print("File Found")

As originally, check_output was returning bytes, thus we pass in encoding here. Also, since you want to search it line by line, we split it with \n. (Tested on Python 3.)

subprocess.check_output: ... By default, this function will return the data as encoded bytes. The actual encoding of the output data may depend on the command being invoked, so the decoding to text will often need to be handled at the application level.

This behaviour may be overridden by setting universal_newlines to True as described above in Frequently Used Arguments. -- cited from https://docs.python.org/3/library/subprocess.html#subprocess.check_output

Upvotes: 1

k.Stavrianos
k.Stavrianos

Reputation: 1

import os
 def find(name):
    for root, dirs, files in os.walk('C:\\');
        if name in files:
            print(root,name)
            print("FINISH")
            input()

try:
    s=input("name:  ")
    find(s)
except:
    None

Upvotes: 0

habet
habet

Reputation: 146

to output the contents of a directory, i would recommend the os module.

import os

content = os.listdir(os.getcwd())

then you have a searchable list.

But are you sure, your file ist named (myfile.txt) ??

Upvotes: -1

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