How do I print my logical volume group UUID to file?

Question

I'm in the process of trying to automate getting the LVGUUID and printing it as a string to a text file, or better piping it in terminal to other commands. All I can do right now is diskutil coreStorage list and then copy/paste the UUID as needed. Is there a faster way to do this?

Answer 1

Note: This answer is just example code as I only have one Core Storage Volume to test against, however, if there's more then one, the awk command could be modified to accommodate accordingly. Although without the output of multiple Core Storage Volumes, I cannot give an example.

If it's the Logical Volume Group UUID, you can user the following example:

$ lvguuid="$(diskutil coreStorage list | awk '/Logical Volume Group/{print $5}')"
$ echo "$lvguuid"
696AD841-1F53-4D33-9496-3E36D33AB270
$ 

In the awk command, you can substitute Logical Volume Group with Physical Volume, Logical Volume Family and change $5 as appropriate. Based on the order of the search string shown in this line, it will be $5, $4, $5.

For Logical Volume, you'll need to use a regex, as in the following example:

lvuuid="$(diskutil coreStorage list | awk '/Logical Volume [A-F0-9]{8}-/{print $4}')"

Understanding the regex:

• Logical Volume [A-F0-9]{8}-

  • Logical Volume matches the characters Logical Volume literally (case sensitive).

• [A-F0-9]{8} - Match a single character present in the list below.

  • {8} Quantifier — Matches exactly 8 times.
  • A-F a single character in the range between A (index 65) and F (index 70) (case sensitive).
  • 0-9 a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive).
  • - matches the character - literally (case sensitive).

So, in my example awk matches Logical Volume 38712F52- and returns:

38712F52-5967-4A49-87D6-C66D4B199F28

---

The above examples set a variable that can be called from the command line or script, however, if you what the output to a file, then use the following example:

diskutil coreStorage list | awk '/Logical Volume Group/{print $5}' > /path/to/filename

---

On my system here's the output of the diskutil coreStorage list command on an encrypted USB Flash Drive:

$ diskutil coreStorage list
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 696AD841-1F53-4D33-9496-3E36D33AB270
    =========================================================
    Name:         Encrypted
    Status:       Online
    Size:         15661490176 B (15.7 GB)
    Free Space:   16777216 B (16.8 MB)
    |
    +-< Physical Volume E0E76F6B-A4E2-466D-B8E5-D5977ECD0522
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk3s2
    |   Status:   Online
    |   Size:     15661490176 B (15.7 GB)
    |
    +-> Logical Volume Family EAF4984B-94C8-49B6-BCC6-76A8724E04D2
        ----------------------------------------------------------
        Encryption Status:       Unlocked
        Encryption Type:         AES-XTS
        Conversion Status:       Complete
        Conversion Direction:    -none-
        Has Encrypted Extents:   Yes
        Fully Secure:            Yes
        Passphrase Required:     Yes
        |
        +-> Logical Volume 38712F52-5967-4A49-87D6-C66D4B199F28
            ---------------------------------------------------
            Disk:               disk4
            Status:             Online
            Size (Total):       15325941760 B (15.3 GB)
            Size (Converted):   -none-
            Revertible:         Yes (unlock and decryption required)
            LV Name:            Encrypted
            Volume Name:        Encrypted
            Content Hint:       Apple_HFS
$