set aPath to current application’s NSString’s stringWithString:"/"
set fileAttr to current application’s NSFileManager’s defaultManager()’s attributesOfFileSystemForPath:aPath |error|:(missing value)
set fRes to (fileAttr’s objectForKey:(current application’s NSFileSystemFreeSize)) as string

usedSpace("/")
–>　　8.4346003456E+10

usedSpace2("/")
–>　　8.4345450496E+10

usedSpaceString("/")
–>　　"84.35 GB"

usedSpaceLongString("/")
–>　　"45.77 GB (45,772,857,344 bytes)"–English user environment
–>　　"45.77 GB (45,772,857,344 バイト)"–Japanese user environment

tell application "Finder"
　　free space of startup disk
end tell
–>　　4.5784592712E+10

on usedSpace(volumePath)
　　set theNSURL to current application’s class "NSURL"’s fileURLWithPath:volumePath –considering "ASOC in Xcode"
　　set {theResult, theSize} to theNSURL’s getResourceValue:(reference) forKey:(current application’s NSURLVolumeAvailableCapacityKey) |error|:(missing value)
　　
　　return theSize as real — integer may be too big for AS
end usedSpace

on usedSpace2(volumePath)
　　set fileAttr to current application’s NSFileManager’s defaultManager()’s attributesOfFileSystemForPath:volumePath |error|:(missing value)
　　
　　return (fileAttr’s objectForKey:(current application’s NSFileSystemFreeSize)) as real — integer may be too big for AS
end usedSpace2

on usedSpaceString(volumePath)
　　set fileAttr to current application’s NSFileManager’s defaultManager()’s attributesOfFileSystemForPath:volumePath |error|:(missing value)
　　set fRes to fileAttr’s objectForKey:(current application’s NSFileSystemFreeSize)
　　
　　–Formatting
　　set sizeString to current application’s NSByteCountFormatter’s stringFromByteCount:fRes countStyle:(current application’s NSByteCountFormatterCountStyleDecimal)
　　
　　return sizeString as text
end usedSpaceString

on usedSpaceLongString(volumePath)
　　set fileAttr to current application’s NSFileManager’s defaultManager()’s attributesOfFileSystemForPath:volumePath |error|:(missing value)
　　set fRes to fileAttr’s objectForKey:(current application’s NSFileSystemFreeSize)
　　
　　–Formatting
　　set theFormatter to current application’s NSByteCountFormatter’s alloc()’s init()
　　theFormatter’s setCountStyle:(current application’s NSByteCountFormatterCountStyleDecimal)
　　theFormatter’s setIncludesActualByteCount:true
　　set sizeString to theFormatter’s stringFromByteCount:fRes
　　
　　return sizeString as text
end usedSpaceLongString

set aFol to choose folder
set aFolPOSIX to POSIX path of aFol

set fRes to freeStorageSpaceG(aFolPOSIX)

tell application "Finder"
　　set driveList to every disk whose format is (MSDOS format) and ejectable is true and startup is false
　　
　　repeat with i in driveList
　　　　set myDisk to disk of (first item of i)
　　　　set myMountPoint to POSIX path of (myDisk as alias)
　　　　–> "/Volumes/JVCCAM_SD/"
　　　　–> "/Volumes/RICOHDCX/"
　　　　set sdRes to detectSDCard(myMountPoint) of me
　　　　–> true –SD Card, false –Not SD Card
　　end repeat
end tell

on detectSDCard(myMountPoint as string)
　　
　　set resData to runCommandString("system_profiler -xml SPStorageDataType") of me
　　set aaDict to (readPlistFromStr(resData) of me) as list
　　set aDictList to (_items of first item of aaDict)
　　
　　repeat with i in aDictList
　　　　set j to contents of i
　　　　
　　　　set aMountPoint to (mount_point of j) as string
　　　　–> "/Volumes/JVCCAM_SD"
　　　　–> "/Volumes/RICOHDCX"
　　　　
　　　　if aMountPoint is not equal to "/" then
　　　　　　if ((aMountPoint & "/") is equal to myMountPoint) then
　　　　　　　　set aDevName to words of (device_name of physical_drive of j)
　　　　　　　　set aMediaName to words of (media_name of physical_drive of j)
　　　　　　　　
　　　　　　　　–SD/SDHC/SDXCのカード検出
　　　　　　　　set aDevF to ("SD" is in aDevName) or ("SDHC" is in aDevName) or ("SDXC" is in aDevName)
　　　　　　　　set aMediaF to ("SD" is in aMediaName) or ("SDHC" is in aMediaName) or ("SDXC" is in aMediaName)
　　　　　　　　
　　　　　　　　if (aDevF and aMediaF) then return true
　　　　　　end if
　　　　end if
　　end repeat
　　
　　return false
end detectSDCard

–文字列で与えたシェルコマンドを実行する
on runCommandString(commandStr as string)
　　set aPipe to current application’s NSPipe’s pipe()
　　set aTask to current application’s NSTask’s alloc()’s init()
　　aTask’s setLaunchPath:"/bin/sh"
　　aTask’s setArguments:{"-c", current application’s NSString’s stringWithFormat_("%@", commandStr)}
　　aTask’s setStandardOutput:aPipe
　　set aFile to aPipe’s fileHandleForReading()
　　aTask’s |launch|()
　　return current application’s NSString’s alloc()’s initWithData:(aFile’s readDataToEndOfFile()) encoding:(current application’s NSUTF8StringEncoding)
end runCommandString