Remove specific lines from a large text file in python

Question

I have several large text text files that all have the same structure and I want to delete the first 3 lines and then remove illegal characters from the 4th line. I don\'t w

Answer 1

As wim said in the comments, sed is the right tool for this. The following command should do what you want:

sed -i -e '4 s/(dB)//' -e '4 s/Best Unit/Best_Unit/' -e '1,3 d' yourfile.whatever

To explain the command a little:

-i executes the command in place, that is it writes the output back into the input file

-e execute a command

'4 s/(dB)//' on line 4, subsitute '' for '(dB)'

'4 s/Best Unit/Best_Unit/' same as above, except different find and replace strings

'1,3 d' from line 1 to line 3 (inclusive) delete the entire line

sed is a really powerful tool, which can do much more than just this, well worth learning.