Adding a suffix to a file using applescript

Replace the ‘set fName’ line with:

set fName to ((items 1 thru ((offset of "." in (get name of aFile)) - 1) of (get name of aFile)) as string) & "_THUMBNAIL" & "." & name extension of aFile

(144742)

set fName to ((items 1 thru ((offset of "." in (get name of aFile)) - 1) of (get name of aFile)) as string) & "_THUMBNAIL" & "." & name extension of aFile

This will fail (or, at least, have unexpected results) if there is a '.' anywhere in the file name.

A more complete solution would strip the filename extension rather than assume that the . is the delimiter

on opensomeFiles

tell application "Finder"

set theList to someFiles

repeat with aFile in someFiles

set fn to name of aFile

set fx to name extension of aFile

set basename to characters 1 through -(2 + (length of fx)) of fn as text

set newname to basename & "_THUMBNAIL." & fx

-- now you can rename the file to newname

set name of aFile to newname

end repeat

end tell

end open

Or another variation...

property fappend : "_THUMBNAIL."

on opensomeFiles

tell application "Finder"

repeat with aFile in someFiles

set x to aFile'sname extension

-- step backwards by 2 to avoid the "."

set newFile to text 1 thru ((offset of x in (aFile as text)) - 2) of (aFile as text) & fappend & x

set name of aFile to newFile

end repeat

end tell

return

end open

Given: Macintosh HD:Users:viking:Desktop:star.png

Result: Macintosh HD:Users:viking:Desktop:star_THUMBNAIL.png