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SweetNGX
SweetNGX

Reputation: 163

Matching variable string with Lua

I'm fighting with the file search script
The x99999999 value is continuously variable. How can I find this value with lua match?
I need to find and change this variable.

/home/data_x99999999_abc_def_0.sh

I actually have code that works but I'm not sure it's a correct regex.

local newpath = s:gsub("(_x)[^_]*(_)", "_static_")

Upvotes: 1

Views: 473

Answers (1)

Piglet
Piglet

Reputation: 28950

I'm not sure it's a correct regex.

Lua patterns are no regular expressions. Compared to regular expressions Lua's string pattens have a different syntax and are more limited.

Your code

local newpath = s:gsub("(_x)[^_]*(_)", "_static_")

replaces "_x" followed by 0 or more non-underscore characters followed by "_" with "_static_"

This is correct but not very elegant.

  1. the captures () are not necessary as you don't make use of them. So "_x[^_]*_" would achieve the same.
  2. if you know that only the x12345678 part changes and that there are only digits after x you can simply use "x%d+" and repalce it with "static". This matches "x" followed by 1 or more digits. Or you include the underscores.
  3. if you only want to match exactly 8 digits you could use "%d%d%d%d%d%d%d%d" or string.rep("%d",8)

Upvotes: 2

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