Searched pattern looks like text9
I search for (text)9
I want to replace with \15 so that I would get text5 but instead it's just giving me text.
Any other character works except for digits.
As it turns out, the PCRE-style back-references do not work.
So, you have to use \015 to replace with the text captured with the first capturing group (\01) and 5.
Since there cannot be more than 99 capturing groups, and both the digits after \ are treated as back-reference group number, \01 is interpreted as the reference to the first group, and the rest are literal digits.
The replacement term \15 is being interpreted as "group 15" - you must escape the "5":
Try replacing with \1\\5, or if that doesn't work (I don't have textwrangler handy) use a look behind:
Search: (?<=text)9
Replace: 5
The look behind doesn't consume input, so only the "9" is matched.
来源：https://stackoverflow.com/questions/31885314/replacing-digits-immediately-after-a-saved-pattern