Repeat keywords at end of every line

[knob]

Good evening, I would like to read a text file and create an output with the results.
I'm new on python and i'm looking a way to develop this code.
Any suggestion on how to start it ?

• Check all lines, looking for KEYWORD.
  
• Once it finds, copy from pos X to pos Y (fixed position, hard-coded )
  
• Write the copied string at end of every line at pos Z (fixed position, hard-coded)
  
• if KEYWORD is found again on the next line the steps above...
  
• writing everything on the output file.
  

Output:
abcabc abc abvc canc KEYWORD  TOBEREPLIC1    TOBEREPLIC1
asd  alskdlask laks dlkal  lakslkalkas       TOBEREPLIC1
aslddsas laskd laskl  lsklklklk asdda        TOBEREPLIC1
                                             TOBEREPLIC1
aksjdaks kajsdkajsd askjaksjd a asdasda      TOBEREPLIC1
                                             TOBEREPLIC1
aksjaaaaaaaaaaaaaaaaaakjaksjd aasdas         TOBEREPLIC1
aksjbbbbbbb b bbbbbbbbbbaksjd adasdas        TOBEREPLIC1
abcasdasdasd asdaasd KEYWORD  TOBEREPLIC2    TOBEREPLIC2
                                             TOBEREPLIC2
aksjasdasdasdasajsasdasdas    a asdsda       TOBEREPLIC2
akasssssssssssssssd askjaksjd adasda         TOBEREPLIC2
aksjdavvvvvvv   sssssssse   eeeeeeee ee      TOBEREPLIC2