Listing Directory Contents using T-SQL

Listing Directory Contents using T-SQL

In many cases during the development of a sophisticated SQL Server Agent job, you might need to access the file system. For example you might want to list the contents of a specific directory and based on the output to proceed to other actions folllowing a series of steps that belong to a broader logic implemented via a SQL Server Agent job.

Don’t worry, there’s nothing stopping you from performing the above operation!

For such and similar purposes you can always use the extended stored procedure xp_cmdshell.

As described in SQL Server BoL, xp_cmdshell takes as a parameter a string and passes it to a Windows command shell for execution. Any output is returned as rows of text.

xp_cmdshell, by default, is disabled within a SQL Server instance and there is a good reason for this. When this extended stored procedure is enabled, it introduces a security risk that you should be aware of. As xp_cmdshell allows executing commands on the Operating System’s level, you should be extremely careful with who has the right to execute this stored procedure. To this end, you should always use xp_cmd with caution.

OK, enough with the theory. Let’s proceed with a practical example and some T-SQL!

–You can enable xp_cmdshell using the following T-SQL statement:
exec sp_configure ‘xp_cmdshell’,1
GO
RECONFIGURE WITH override
GO

Then, if you want for example to list the contents of the directory “c:tmp” you can do so by executing the following T-SQL statement:

— You first create a temporary table for storing the contents of the directory.
CREATE TABLE #dirContents
(
contents NVARCHAR(255)
)
GO

— You then execute xp_cmdshell by using the DOS “dir” command.
— You store the output to the temporary table created earlier.
— The contents are stored as string expressions line-by-line.
— Each empty line is a NULL.
INSERT INTO #dirContents
EXEC xp_cmdshell ‘dir “c:tmp”‘;

— You can then scan the table for the output and analyze the data
— using string manipulation techniques
SELECT *
FROM #dirContents

If you want to disable xp_cmdshell, you can do so as follows:

exec sp_configure ‘xp_cmdshell’,0
GO
RECONFIGURE WITH override
GO

I hope you found the post useful!

Cheers!

Artemakis Artemiou
Artemakis Artemiou is a Senior SQL Server and Software Architect, Author, and a 9 Times Microsoft Data Platform MVP (2009-2018). He has over 15 years of experience in the IT industry in various roles. Artemakis is the founder of SQLNetHub and TechHowTos.com. Artemakis is the creator of the well-known software tools Snippets Generator and DBA Security Advisor. Also, he is the author of many eBooks on SQL Server. Artemakis currently serves as the President of the Cyprus .NET User Group (CDNUG) and the International .NET Association Country Leader for Cyprus (INETA). Artemakis's official website can be found at aartemiou.com.