Strange size conversion

[Jean-Baptiste_LE_STA]

I must be missing something real important, here is my problem :

using the ‘info for’ command I’m retrieving the size of a file (in bytes) adI 'm trying to convert it to kilobytes or megabytes using the formula :
1 kilobytes = 1024 bytes
1 megabytes = 1024 kilobytes = (1024)^2 bytes

And the result is not whta is shown in the info window. Can someone explain it to me?

[Jean-Baptiste_LE_STA]

Notice : when I’m using the “Finder” physical size for (pathToFile), I have teh correct result, but I’d like not to use the “Finder”.

So there is a difference between the real size of the file, and the place this file is taking on the disk (which is understandable)

[Rob]

I must be missing something real important, here is my problem :

using the ‘info for’ command I’m retrieving the size of a file (in bytes) adI 'm trying to convert it to kilobytes or megabytes using the formula :
1 kilobytes = 1024 bytes
1 megabytes = 1024 kilobytes = (1024)^2 bytes

And the result is not whta is shown in the info window. Can someone explain it to me?

Here are a couple of quotes from Chris Nebel, AppleScript engineer. These statements were made at different times in response to different questions, but they might help. Obviously, you’ve already touched on some of the issues mentioned by Chris.

When the Finder reports file sizes in KB or MB, it’s using the computer-y definitions of K and M, that is, 2^10 and 2^20. (And of course G means 2^30.) Yes, this contradicts the NIST and the IEC, and yes, I know about kebibytes, mebibytes, and gibibytes, but I have yet to meet anyone who doesn’t roll their eyes at their mention, let alone actually use them. I blame the disk manufacturers for the whole mess. It’s not really fair, but it makes me feel better.

“Info for” returns the logical size of the item (i.e., how many bytes of data are there), whereas the Finder usually reports the physical size (i.e., how much space does it take up), so you were spot on there. If you look in a Get Info window, you should see that “info for” agrees with the “bytes” number, while the size column agrees with the “on disk” number.

“Info for” will also include invisible files in its total, where the Finder won’t. (On Mac OS 9, anyway – Finder X does.) “But I don’t make any invisible files!” you cry. Well, you probably didn’t, but the Finder does all the time – whenever you create a custom folder icon, attach a folder action, or adjust the width or ordering of the columns in a list view, that information gets stored in an invisible file. Enough of them will add up to a noticeable amount.

[Jean-Baptiste_LE_STA]

Thanks Rob
Here is a little handler dedicated to finding the size taken by the file on the disk (physical size) without using the Finder

on getFileSize(PathToFile)
	set myOffSet to offset of "/" in (reverse of characters of PathToFile as string)
	set lastcar to ((count PathToFile) - myOffSet) + 1
	set ParentPath to characters 1 thru lastcar of PathToFile as string
	set FileName to characters (lastcar + 1) thru -1 of PathToFile as string
	do shell script "cd " & ParentPath & ";" & "ls -sk | grep " & FileName & " | awk '{print $1}'"
end getFileSize

[Jean-Baptiste_LE_STA]

but it works only for file that are less that 1 Mo

[Plaid_Cow_Solutions]

This shorter snippet should work just as well.

on getFileSize(PathToFile)
   do shell script "ls -skc1 " & PathToFile & " | awk '{print $1}'"
end getFileSize

What do you get if the file size is greater than 1 MB?

[Jean-Baptiste_LE_STA]

Thanks for the tip, it’s working well with your routine

(et voila, second problem solved…)