Replace text between 2 strings

Question

I'm trying to replace text between 2 strings using Python or sed. I read all what I found on Stack Overflow, but my skills don't seems to be enough to adapt what I found to my problem.

I have 2 files :

1. Courses.txt:

   Course = bla
   Room number(1)
   url http://foobar
   

2. dst.txt:

   //Start
   
   Course = foo
   Room Number(2)
   url http://bar
   
   //End
   

My goal is to replace what is between //Start and //End in dst.txt with what is read in Courses.txt.

I looked here :

• sed/awk/bash to replace text between two strings with external file contents

• Replace all text between 2 strings python

• Regex replace text between delimiters in python

but was not able to use them.

Answer 1

sed '\#^//Start#,\#^//End#{
   \#^//End# !d
   r Courses.txt
   }' dst.txt

Explanation:

• for every thing between start and end (\#//^Start#,\#//^End#) using a different delimiter \# than default /, execute sub action inside {}
  • for all line except end (\#^//end# !), delete the line (d) [and cycle to next line]
  • [if not the case, so contain end], replace by (read) content of file Course.txt

Answer 2

 import re
 with open('Courses.txt', 'r') as f1, open('dst.txt', 'r') as f2:
        text = f1.read()
        text2 = f2.read()
        ntext = re.sub(r'(//Start.*?\n+)(.*)(//End)',r'\1' + text + r'\3',text2, flags=re.M|re.DOTALL)

    with open('dst.txt', 'w') as fout:
        fout.write(ntext)

Answer 3

i know this late but here is my solution: note this will overwrite the content of original file so make sure to back it up

f = open("test.txt","r")
lines = f.readlines()
f.close()
f = open("test.txt","w")
start=False
for line in lines:
    if line.strip() == "starting string":
        f.write(line)
        start=True
    elif line.strip() == "ending string":
        f.write("line1 content\nline2 content\n")
        start=False
    if start == False:
        f.write(line)
f.close()