Question

In a file (.py file) I have some classes with different name but some have common variables:

class myClass1:
  f1 = '512kB'
  f2 = 2
  f3 = 'something1'

class myClass2:
  f1 = '512kB'
  f2 = 6
  f3 = 'something2'

I want to write a bash script and use SED to replace some strings. The problem is I want to first find myClass2 and then replace f1 = '512kB' with f1 = '1MB'

If I use

sed -i 's/f1 = '512kB'/f1 = '1MB'/g' /path/to/file

it will replace that string for both classes.

Answer 1

 sed -i "/^class myClass2:/,/^class/s/f1 = '512kB'/f1 = '1MB'/" path/to/file.py

This assumes your class declarations are never indented.

However, given that this is Python, wouldn’t it make more sense to write a simple subroutine to set the variable’s value, rather than hard-code it?