Apple - Changing text applied when duplicating file in Finder

Open /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj/

^{Use Show Package Contents to browse the package in Finder, or open using Terminal, etc.}
Open Localizable.strings in BBEdit or other editor capable of editing .strings files.
N4 contains the string that is used to name the duplicate file.
```
^0 copy
```
^{^0 is the previous file's name. Make sure to keep this to retain the name of the previous file.}
Edit the string how you wish. For example, to duplicate test as test_copy instead of test copy, use…
```
^0_copy
```
Save and relaunch Finder.
```
killall -HUP Finder
```

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