Add a log partition to a Fedora live USB stick

Steps#

1. Find the stick's disk number. In an elevated prompt run diskpart, then list disk, and take the number of the disk whose size matches the stick (<N>). Then check it:

   select disk <N>
   detail disk
   

   Expected: the stick's model name, Type : USB and Boot Disk : No (my output is in step 3). If the model is not your stick or Boot Disk says Yes, type exit and start over.

   WarningWrong disk = data loss

   create partition and format act on whatever disk is selected. In a script they run straight after detail disk without stopping, so check the number interactively first. I did not keep my list disk output.

2. Write the diskpart script as logs-partition.txt, with your <N>:

   select disk <N>
   detail disk
   create partition primary
   format fs=exfat label=LOGS quick
   assign
   list partition
   

   create partition primary without size= takes all the free space after the image.

3. Run it from the elevated prompt with diskpart /s logs-partition.txt [UNVERIFIED: my exact command line was not kept; the saved output below is the complete output of the script above, with <N> = 1]:

   Microsoft DiskPart version 10.0.26100.1150
   
   Copyright (C) Microsoft Corporation.
   On computer: host
   
   Disk 1 is now the selected disk.
   
   SanDisk Cruzer Blade USB Device
   Disk ID: <DISK_ID>
   Type   : USB
   Status : Online
   Path   : 0
   Target : 0
   LUN ID : 0
   Location Path : UNAVAILABLE
   Current Read-only State : No
   Read-only  : No
   Boot Disk  : No
   Pagefile Disk  : No
   Hibernation File Disk  : No
   Crashdump Disk  : No
   Clustered Disk  : No
   
     Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
     ----------  ---  -----------  -----  ----------  -------  ---------  --------
     Volume 3     D                       Removable   3349 MB  Unusable
   
   DiskPart succeeded in creating the specified partition.
   
   
       0 percent completed
       0 percent completed
     100 percent completed
   
   
   DiskPart successfully formatted the volume.
   
   DiskPart successfully assigned the drive letter or mount point.
   
     Partition ###  Type              Size     Offset
     -------------  ----------------  -------  -------
     Partition 1    Primary           3349 MB    32 KB
     Partition 2    System              30 MB  3349 MB
   * Partition 3    Primary             11 GB  3380 MB
   

   Expected: three partitions, the new one last and selected (*). Partitions 1 and 2 are the live image (Windows lists its main partition as Unusable; leave it so).

4. Copy your scripts onto LOGS (it now has a drive letter in Windows, <L>). Create the target folder first: New-Item -ItemType Directory <L>:\live-test [UNVERIFIED: how the folder was created on my stick was not recorded; without it Copy-Item fails with "Could not find a part of the path"]. Then I used this PowerShell script, which finds the volume by label, copies five files and compares the first 12 hex digits of each SHA-256; put your own folder and file names in $src and the list:

   # Copy the live-test scripts to the LOGS partition of the Fedora stick and compare hashes.
   $v = Get-Volume -FileSystemLabel LOGS -ErrorAction SilentlyContinue
   if (-not $v) { 'LOGS not mounted'; return }
   $src = 'C:\Users\<YOU>\work\<REPO>\linux\live-test'
   $dst = "$($v.DriveLetter):\live-test"
   foreach ($f in 'ux3405-quick.sh', 'ux3405-online-run.sh', 'ux3405-last-run.sh', 'ux3405-dump.sh', 'ux3405-s3-test.sh') {
       Copy-Item -LiteralPath (Join-Path $src $f) -Destination (Join-Path $dst $f) -Force
       $a = (Get-FileHash (Join-Path $src $f)).Hash.Substring(0, 12)
       $b = (Get-FileHash (Join-Path $dst $f)).Hash.Substring(0, 12)
       '{0,-22} repo {1} stick {2} {3}' -f $f, $a, $b, $(if ($a -eq $b) { 'ok' } else { 'MISMATCH' })
   }
   Get-ChildItem $dst | Select-Object Name, Length | Format-Table -AutoSize | Out-String
   

   Expected: one ok line per file. I did not keep this script's output.

5. Boot the stick and run from LOGS. In the live session the partition is at /run/media/liveuser/LOGS [UNVERIFIED: whether the session mounted it by itself or when I opened it in Dolphin; the kernel logged the exFAT mount 123 s and 150 s after boot, shortly before my scripts started, which fits a mount on opening it]. Run scripts from there, for example cd /run/media/liveuser/LOGS/live-test and sudo bash <SCRIPT>.sh, and have each script write its log next to itself and sync it before anything risky.