In my text file there are many lines whose contents are almost the same. Here are some of them.
So, what I want is to overwrite the / with - on every line and then insert - in front of the line exactly above the line that has the / character overwritten.
Right now I'm trying:
cat text | sed "/\//s/^/- /g;s/\/ /\n- /g"
Input file:
1
00:00:00,000 --> 00:00:00,000
You are older.
2
00:00:00,000 --> 00:00:00,000
By length of a sunset.
/ Is older.
3
00:00:00,000 --> 00:00:00,000
Soona.
4
00:00:00,000 --> 00:00:00,000
Noa!
/ Noa, wait!
Expected output:
1
00:00:00,000 --> 00:00:00,000
You are older.
2
00:00:00,000 --> 00:00:00,000
- By length of a sunset.
- Is older.
3
00:00:00,000 --> 00:00:00,000
Soona.
4
00:00:00,000 --> 00:00:00,000
- Noa!
- Noa, wait!
I find with this kind of request (do something on the previous line), it's easier to reverse the file, do something on the next line, then re-reverse the file.
tac file | awk 'sub(/^\//, "-") {print; getline; $1 = "- " $1)} 1' | tac
Here, I'm taking advantage of the fact that the sub() function returns the number of substitutions made, which can be treated as a boolean value.
With sed
tac file | sed '/^\// { s//-/; N; s/\n/&- /; }' | tac
This is with the native sed on my Mac. I don't recall if GNU sed complains about the semicolon before the closing brace