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How to replace a string of text with input from another file

rated 0 times [ 0] [ 0] / answers: 1 / hits: 1449 / 3 Years ago, tue, may 18, 2021, 10:40:12

I am working on a script to configure a server. Basically the script installs several services and copies configuration files in to place.

I would like to replace the username in one of the configuration files with the content of another file.
The input file is one line of text which contains the username.
The config file has multiple lines of text but only one line refers to the username.

How do I replace the username of the config file with the username stored in the input file?

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naldis

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1 Year ago

answered 3 Years ago humbire · Accepted Answer

Assuming the actual username in the targeted file is preceded by USER: (if not, change it in the head section of the script), here is a python solution to do the job.

Simply copy the script into an empty file, save it as replace_username.py and run it with the source file (with the correct user name) and the destination file as arguments:

python3 /path/to/replace_username.py <sourcefile> <destination_file>

The script:

#!/usr/bin/env python3



import sys



source = sys.argv[1]       # the file with the password you want to insert

destination = sys.argv[2]  # the targeted configuration file

prefix="USER:"             # prefix, check if it is exactly as in your files



with open(source) as src:

    name = src.read().strip()



with open(destination) as edit:

    lines = edit.readlines()



for i in range(len(lines)):

    if lines[i].startswith(prefix):

        lines[i] = prefix+name+"

"



with open(destination, "wt") as edit:

    for line in lines:

        edit.write(line)