How to check if the file exists or not before bulk insert

How to check if the file exists or not before bulk insert.

I would like to skip the bulk insert if the file doesn't exist.

Information:

I use Stored Procedures to run Bulk insert statement.

The stored procedures is call by package.

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I test it at query analyzer and show the error when file don't exists.

Error message

Server: Msg 4860, Level 16, State 1, Line 1
Could not bulk insert. File 'E:\POLL41.fmt' does not exist.

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Code

CREATE PROCEDURE sp_InsertPoll59
AS
declare @strsql varchar(5000)

select @strsql = 'BULK INSERT POLL59 '
select @strsql = @strsql +' FROM ''E:\POLL.DWN'''
select @strsql = @strsql +' WITH (FORMATFILE = ''E:\POLL.fmt'')'
exec(@strsql)
GO