"LxRun.exe /setdefaultuser" fails if temp folder is not accessible

[zzpxyx]

• A brief description
  LxRun.exe /setdefaultuser will fail if Windows temp folder is not accessible, either because of privilege or unsupported file systems like RAM disk, etc.
• Expected results
  The default user should be set to the given user without any error.
• Actual results (with terminal output if applicable)
  An error message like:
  /bin/bash: /mnt/d/TEMP/uid.txt: No such file or directory
  or
  /bin/bash: /mnt/c/WINDOWS/TEMP/uid.txt: No such file or directory
  Note that the first error message appears when my Temp folder is on a RAM disk, and the second appears when I'm using the system-level Temp folder (C:\Windows\Temp).
• Your Windows build number
  10.0.14393
• Steps / commands required to reproduce the error
  Set the Temp folder to a RAM disk or use the system-level Temp folder. Then execute the command:
  LxRun.exe /setdefaultuser <username>

[rainabba]

First hit on Google for this error, 21 days ago and no so much as another comment?! I'm not REALLY the 2nd person who's hit this bug am I?

I followed all instructions to get this far and had no other issues along the way so I don't think I caused it. I even used an elevated cmd prompt and tried lxrun.exe /setdefaultuser after hitting it the 2nd time so I don't think it's actually a permissions error on the standard Windows side and I started investigating.

My TEMP environment variable reports as TEMP=C:\TEMP, but my actual folder is c:\Temp. This cannot be changed at standard runtime because of app using the folder and being a Linux user, I'm aware of case issues in POSIX environments so I updated my environment variable with set TEMP=c:\Temp then tried again and it worked.

Workaround: set TEMP={your actual temp folder, including case sensitivity}

Fix: MS should check any environment variables and/or registry settings that this bash environment will be dependant on and make sure case is updated in those variables if it doesn't match. In Linux, suggesting such a thing would seem absurd since it's a standard requirement, but for a Windows user with limited bash experience, something this simple could be a real nightmare.

UPDATE: Turns out that I ended up here because I didn't like C:\WINDOWS\TEMP as a temp folder (because filling up the OS folder with temp content is asinine) and I created a new one in a more sensible partition then overwrote the system variable with a user variable without considering case.

[benhillis]

This had the same root cause as #598 for which a fix is incoming. Marking this as a duplicate. Thanks again for reporting!

[kimfaint]

I hit this issue when installing today. Cause was on my system C:\Temp was actually C:\temp. Had to rename directory then rerun lxrun.exe /setdefaultuser.

[benhillis]

Which Windows build are you on? This is fixed in recent insider builds.

[kimfaint]

OS Build 14393.0.

[leonhui]

**/bin/bash: /mnt/c/TEMP/uid.txt: Input/output error**

Bug occurs for me if the TEMP directory is a JUNCTION.

My TEMP=C:\TEMP, where TEMP is also mounted to a different volume via diskmgmt.msc.

Under cmd.exe it shows it as:

12/02/2016 02:31 <JUNCTION> TEMP [\??\Volume{xxxxxxxxxxxxxxxxxxxxxxxxxx}\]

However, under bash, ls or ll does not show it but cd /mnt/c/TEMP errors with

bash: cd: TEMP: Input/output error

[aseering]

@leonhui -- that sounds related to #559 and #1475 . In general, WSL doesn't support Windows Junctions right now. Those tickets have more details.

[benhillis]

@leonhui - Are you on build 14393? This will not be a problem in recent insider builds.