Find and replace certain texts in file using python

Solution 1:

Assuming you can't change your txt file to json, if you are looking to only change the LOADLIST that comes after IFSIM, you could use a state to check that the loop has reached IFSIM.

entry = "outfile.txt"

reading_file = open("myFile.txt","r")

new_file_content = ""
isIfsim = False
for line in reading_file:
    stripped_line = line.strip()
    if "IFSIM" in stripped_line:
        isIfsim = True
    if isIfsim:
        if 'LOADLIST = "";' in stripped_line:
            new_line = stripped_line.replace('LOADLIST = "";', 'LOADLIST = "init";')
            new_file_content += new_line +"\n"
            isIfsim = False
        else:
            new_file_content += stripped_line +"\n"
    else:
        new_file_content += stripped_line +"\n"
reading_file.close()

writing_file = open(entry, "w")
writing_file.write(new_file_content)
writing_file.close()