Tag: RunAs

An Update on the RunAs Command


This is an update of a post that originally appeared on May 14, 2014.

Recently I wrote the Simulating Users with the RunAs Command post that describes how to use the RunAs command to perform tasks that the user’s account can’t normally perform. (The basics of using the RunAs command appear in Windows Command-Line Administration Instant Reference.) A number of you have written to tell me that there is a problem with using the RunAs command with built-in commands—those that appear as part of CMD.EXE. For example, when you try the following command:

RunAs /User:Administrator "md \Temp"

you are asked for the Administrator password as normal. After you supply the password, you get two error messages:

RUNAS ERROR: Unable to run - md \Temp
2: The system cannot find the file specified.

In fact, you find that built-in commands as a whole won’t work as anticipated. One way to overcome this problem is to place the commands in a batch file and then run the batch file as an administrator. This solution works fine when you plan to execute the command regularly. However, it’s not optimal when you plan to execute the command just once or twice. In this case, you must execute a copy of the command processor and use it to execute the command as shown here:

RunAs /User:Administrator "cmd /c \"md \Temp""

This command looks pretty convoluted, but it’s straightforward if you take it apart a little at a time. At the heart of everything is the md \Temp part of the command. In order to make this a separate command, you must enclose it in double quotes. Remember to escape the double quote that appears within the command string by using a backslash (as in \").

To execute the command processor, you simply type cmd. However, you want the command processor to start, execute the command, and then terminate, so you also add the /c command line switch. The command processor string is also enclosed within double quotes to make it appear as a single command to RunAs.

Make sure you use forward slashes and backslashes as needed. Using the wrong slash will make the command fail.

The RunAs command can now proceed as you normally use it. In this case, the command only includes the username. You can also include the password, when necessary. Let me know if you find this workaround helpful at [email protected].

Simulating Users with the RunAs Command

This is an update of a post that originally appeared on April 26, 2011.

One of the problems with writing applications, administering any network, or understanding system issues is to ensure that you see things from the user’s perspective. It doesn’t matter what your forte might be (programmer, administrator, DBA, manager, or the like), getting the user view of things is essential or your efforts are doomed to failure. Of course, this means seeing what the user sees. Anyone can run an application at the administrator level with good success, but the user level is another story because the user might not have access to resources or rights to perform tasks correctly.

Most knowledgeable users know that you can simulate an administrator by right clicking the application and choosing Run As Administrator from the context menu. In fact, if you Shift+Right Click the application, you’ll see an entry for Run As A Different User on the context menu that allows you to start the application as any user on the system. However, the GUI has limitations, including an inability to use this approach for batch testing of an application. In addition, this approach uses the RunAs command defaults, such as loading the user’s profile, which could cause the application to react differently than it does on the user’s system because it can’t find the resources it needs on your system.

A more practical approach is to use the RunAs command directly to get the job done. You can see some basic coverage of this command on page 480 of Windows Command-Line Administration Instant Reference. To gain a basic appreciation of how the user views things, simply type RunAs /User:UserName Command and press Enter (where UserName is the user’s fully qualified logon name including domain and Command is the command you wish to test). For example, if you want to see how Notepad works for user John, you’d type RunAs /User:John Notepad and press Enter. At this point, the RunAs command will ask for the user’s password. You’ll need to ask the user to enter it for you, but at that point, you can work with the application precisely as the user works with it.

Note that I highly recommend that you create test user accounts with the rights that real users have, rather than use a real user’s account for testing. Otherwise, if something goes wrong (and it usually does), you’ve damaged a real user’s account. Make sure you follow all of the usual policies to create this test user account and that you have as many test user accounts as needed to meet your organization’s needs.

Of course, many commands require that you provide command line arguments. In order to use command line arguments, you must enclose the entire command in double quotes. For example, if you want to open a file named Output.TXT located in the C:\MyDocs folder using Notepad and see it in precisely the same way that the user sees it, you’d type RunAs /User:John “Notepad C:\MyDocs\Output.TXT” and press Enter.

In some cases, you need to test the application using the users credentials, but find that the user’s profile gets in the way. The user’s system probably isn’t set up the same as your system, so you need your profile so that the system can find things on your machine and not on the user’s machine. In this case, you add the /NoProfile command line switch to use your profile. It’s a good idea to try the command with the user’s profile first, just to get things as close as you can to what the user sees. The default is to load the user’s profile, so you don’t have to do anything special to obtain this effect.

An entire group of users might experience a problem with an application. In this case, you don’t necessarily want to test with a particular user’s account, but with a specific trust level. You can see the trust levels setup on your system by typing RunAs /ShowTrustLevels and pressing Enter. To run an application using a trust level, use the /TrustLevel command line switch. For example, to open Output.TXT as a basic user, you’d type RunAs /TrustLevel:0x20000 “Notepad C:\MyDocs\Output.TXT” and press Enter. The basic trust levels are:

  • 0x40000 – System
  • 0x30000 – Administrator
  • 0x20000 – Basic User
  • 0x10000 – Untrusted User

Many people are experiencing problems using the /ShowTrustLevels and /TrustLevel command line switches with newer versions of Windows. The consensus seems to be that Microsoft has changed things with the introduction of UAC and that you’ll need to work with the new Elevation Power Toys to get the job done. You may also want to review the article PowerToys running with administrator permissions because it provides some insights that may be helpful in this case as well. I’d be interested in hearing about people’s experiences. Contact me at [email protected].