How can I map a network drive without hardcoding a drive letter as a batch file

Question

I need to map a network drive with a batch file, but don't want to specify the drive letter.

The batch file is used as part of a deployment process; I call the batch file from CruiseControl.Net, the batch file needs to map a UNC path which requires credentials to authenticate. Then the batch file calls RoboCopy to deploy the website from the output directory to the destination (and excludes some files and folders). Finally the batch deletes the network drive.

The problem is that this isn't scalable, it's fine when there are only a few projects but we've now got 20 projects using this approach and are running out of drive letters to map. I don't want to re-use drive letters as they could collide - which would be bad.

This is an example of the batch file:

@echo off
net use x: \\192.168.0.1\Share\wwwroot\MyProject /user:mydomain\myuser MyP455w0rd
robocopy.exe "W:\wwwroot\MyProject" x:\ *.* /E /XO /XD "App_Data/Search" "*.svn" /XF "sitefinity.log" "Thumbs.db" /NDL /NC /NP
net use x: /delete

Answer 1

If you don't have multiple network shares connected simultaniously, you can make net use * assign a free drive letter for you. Afterwards you can use robocopy to access the share via its UNC path and release any connected share with net use * /delete.

Something like this:

@echo off
net use * \\192.168.0.1\Share\wwwroot\MyProject /user:mydomain\myuser MyP455w0rd
robocopy.exe "W:\wwwroot\MyProject" "\\192.168.0.1\Share\wwwroot\MyProject" *.* /E /XO /XD "App_Data/Search" "*.svn" /XF "sitefinity.log" "Thumbs.db" /NDL /NC /NP
net use * /delete /yes

EDIT:

As I learned from some researches, you can simply map the share without assigning a drive letter. It is then mapped anonymously, only by its remote UNC path. This way you can also remove the mapping by specifiying only its remote name.

This should work:

@echo off
net use \\192.168.0.1\Share\wwwroot\MyProject /user:mydomain\myuser MyP455w0rd
robocopy.exe "W:\wwwroot\MyProject" "\\192.168.0.1\Share\wwwroot\MyProject" *.* /E /XO /XD "App_Data/Search" "*.svn" /XF "sitefinity.log" "Thumbs.db" /NDL /NC /NP
net use \\192.168.0.1\Share\wwwroot\MyProject /delete

Answer 2

Ok... this might not be glamourous but this is how I'm doing this now; a basic try catch approach. Try to map a drive and if it's in use then goto the next step. I've illustrated this with just 2 attempts, but it's not hard to extend it to 4, 10 or more drive letters.

Yes it does offend my programming sensibilities, I don't like the repetion of code. Unfortunately I don't know how I could pass the path and credentials into the batch file as I don't call it myself, CruiseControl.net calls it without parameters.

@echo off

:START
net use z: \\192.168.0.1\Share\wwwroot\MyProject /user:mydomain\myuser MyP455w0rd
if %ERRORLEVEL% ==2 goto Y
ROBOCOPY HERE
net use z: /delete
exit

:Y
net use y: \\192.168.0.1\Share\wwwroot\MyProject /user:mydomain\myuser MyP455w0rd
if %ERRORLEVEL% ==2 goto W
ROBOCOPY HERE
net use y: /delete
exit

:W
sleep 20
goto START