Day 3–101 Days of DevOps — A python script to search for a file

Welcome to Day 3of 101 Days of DevOps. The topic for today is a python script to search for a file. As a DevOps/System Administrator, this is one of the common tasks we encounter as a part of our daily job. The idea behind it is to create a find utility using Python to pass directory names and files to search.

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Prashant Lakhera

Solution Video(A python script to search for a file)

On Day 1, we discussed OS Module. As part of the discussion, we discussed os.walk(). If you want to brush your concept, I am attaching the link; else, please check the above video if you directly want to go to the solution.

101 Days of DevOps

So far, our code looks like this, whereby using os.walk(), we are iterating over the /etc directory and then using os.path.join() we combine directory with the filename.

import os

for dirpath, dirname, filename in os.walk("/etc"):
    for file in filename:
        comp_path= os.path.join(dirpath,file)

To find out the specific file, we can use the if statement and then only print the complete path if the file matches.

if file == "hosts":
    print(comp_path)

So our complete code will look like below.

import os

for dirpath, dirname, filename in os.walk("/etc"):
    for file in filename:
        comp_path= os.path.join(dirpath,file)
        if file == "hosts":
            print(comp_path)

If you save this code in find_files.py and search for hosts file in /etc directory, you will get the below output.

python3 find_files.py           
/etc/hosts

The second version of this script is to make it user-friendly so that it will accept arguments like the path to search(e.g.,/etc.) and then filename(hosts) on the command line; we will achieve that with the help of the argparser module.

These are the steps you need to follow to use argparse

1. Import the Python argparse library

import argparse

2. Create the parser

my_parser = argparse.ArgumentParser(description='Reading the directory path to find the file')

3. Add optional and positional arguments to the parser. Here we are passing two-argument pathname to specify the path and filesearch for the file to search.

my_parser.add_argument("pathname",
help='Please enter the directory path ')

my_parser.add_argument("filesearch",
help='Please enter the filename to search')

4. Execute .parse_args()

args = my_parser.parse_args()

If you execute your script with the -h(help) option, you will get the output below.

python3 find_files.py -h
usage: find_files.py [-h] pathname filesearch
Reading the directory path to find the file
positional arguments:
  pathname    Please enter the directory path
  filesearch  Please enter the filename to search
optional arguments:
  -h, --help  show this help message and exit

Now you need to make few changes to your code. Rather than passing /etc to os.walk(), you need to pass args.pathname, and similarly, rather than passing filename directly, i.e., hosts, you need to pass args.filesearch.

for dirpath, dirname, filename in os.walk(args.pathname):
    for file in filename:
        comp_path= os.path.join(dirpath,file)
        if file == args.filesearch:
            print(comp_path)

To execute your script.

python3 find_files.py /etc hosts
/etc/hosts

Assignment:

1. Write a simple script to find a file greater than X days old. X can be any number, let say 7 days.

Hint: You need to use the datetime module.

I am looking forward to you guys joining the amazing journey.

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