The fastest way to identify a drive's filesystem on macOS is through Terminal using either diskutil or mount commands.

# Method 1: Using diskutil (most detailed)
diskutil list
diskutil info /dev/diskXsY | grep "File System Personality"

# Method 2: Using mount (quick overview)
mount | grep "/Volumes"

Here's how to interpret common filesystem identifiers:

• APFS: "APFS" (Apple File System, 64-bit only)
• HFS+: "Journaled HFS+" (Mac OS Extended)
• FAT32: "MS-DOS FAT32"
• exFAT: "ExFAT"
• NTFS: "NTFS" (read-only by default on macOS)

For GUI users:

1. Open Disk Utility (Applications > Utilities)
2. Select the volume (not the physical disk)
3. Check the "Format" field in the bottom section

To check if your disk uses GPT or MBR partition scheme:

diskutil list /dev/diskX | grep "Partition Type"

Here's a complete example for checking an external SSD:

$ diskutil list
/dev/disk2 (external, physical):
   #: TYPE NAME SIZE IDENTIFIER
   0: GUID_partition_scheme *500.1 GB disk2
   1: EFI EFI 209.7 MB disk2s1
   2: Apple_APFS Container disk3 499.9 GB disk2s2

$ diskutil info disk3 | grep "File System Personality"
   File System Personality: APFS

• If commands return "Permission denied", prefix with sudo
• Unmounted volumes won't show in mount output - use diskutil instead
• For network drives, use mount or nfsstat

Add this to your .bash_profile for quick filesystem checks:

fsinfo() {
    if [ -z "$1" ]; then
        echo "Usage: fsinfo /dev/diskXsY or /Volumes/Name"
        return 1
    fi
    diskutil info "$1" | grep -E "File System Personality|Volume Name|Mount Point|Partition Type"
}

The fastest way to check filesystem info on macOS is through Terminal:

diskutil info /dev/diskXsX | grep "File System Personality"

For example:

diskutil info /dev/disk2s1 | grep "File System Personality"
   File System Personality:  MS-DOS FAT32

For comprehensive filesystem metadata:

diskutil info /dev/diskXsX | grep -E "File System Personality|Name (User Visible)|Volume Name|Mount Point|Partition Type"

Sample output for an APFS volume:

   File System Personality:  APFS
   Name (User Visible):      APFS
   Volume Name:             Macintosh HD
   Mount Point:             /
   Partition Type:          7C3457EF-0000-11AA-AA11-00306543ECAC

Using the mount command:

mount | grep /dev/disk

Example output showing filesystem type:

/dev/disk3s1 on /Volumes/Backup (msdos, local, nodev, nosuid, noowners)

For developers needing filesystem detection in apps:

import Foundation

func getFilesystemType(for path: String) -> String? {
    let keys: [URLResourceKey] = [.volumeSupportsHardLinksKey]
    let url = URL(fileURLWithPath: path)
    
    do {
        let values = try url.resourceValues(forKeys: Set(keys))
        return values.volumeLocalizedFormatString
    } catch {
        print("Error: \(error.localizedDescription)")
        return nil
    }
}

if let fsType = getFilesystemType(for: "/Volumes/External") {
    print("Filesystem type:", fsType)
}

To determine if a filesystem is 32-bit or 64-bit:

diskutil apfs list

Look for "APFS Container (64-bit)" in the output. For HFS+ volumes:

diskutil cs list

• Always use the disk identifier (like disk2s1) rather than mount points
• For encrypted volumes, you may need to unlock them first
• Network drives may report different filesystem information