Get Help text output when using -stay_open

[Curtis]

To get exiftool help when using exiftool.exe in the Windows command window, I just enter exiftool<CR> and all of the exiftool help text is shown.

I would like to get that same text at runtime when I'm using -stay_open.  I understand why just sending -execute with no previous input since the last -execute does not work because then in the situation when an 'empty' -execute needs to be sent to get the {ready} response when the -q or -T options are used, would then generate a lot of output (all the help text).

So I was hoping that there is an option I can send exiftool to have it return the help text, maybe something like -help or -?  ? 

Or maybe there is another 'easy' way to get the help text at runtime when using -stay_open?

Thanks!
Curtis

[Phil Harvey]

Hi Curtis,

Interesting.  I never thought of this.  In general, one does "perldoc exiftool" to get the help, but that doesn't work with the Windows version.  I'll think about adding a -help option.

- Phil

[Curtis]

Thanks for considering it!   

[Phil Harvey]

Hi Curtis,

I looked into this.  Getting the help via -stay_open is a bit problematic since it uses a pager which requires keyboard input to page through the document.  I don't know of a good way to handle this.

- Phil

[Curtis]

That's OK, for now I ran exiftool once and piped the output to a .txt file and then in my program I just read that file in.  But, when exiftool help documentation changes with later versions I will not have the latest help text....

Hmmm..... maybe I'll try during my program initialization to run exiftool once in a process and NOT use -stay_open, pipe output to a file then read that .txt file.  That way my help file will always match the exiftool.exe that I am currently using.  Hah!  solved  (I hope) 

Curtis

[Curtis]

Got that working!  So I just start exiftool, get all output, since I can't wait for {ready} I just wait until the exiftool process has exited.

Curtis   

For anyone interested here is the vb.net code to run exiftool once and get the help text it outputs:

Code Select Expand

    Private Shared _ExifToolHelpString As String = ""

    Public Shared Function ExifToolHelp() As String
        If String.IsNullOrEmpty(_ExifToolHelpString) AndAlso Not String.IsNullOrEmpty(ExifToolExeFn) Then
            With New Process
                .StartInfo.FileName = ExifToolExeFn  '<-- need to set this to where ever you are getting your exiftool.exe file from
                .StartInfo.UseShellExecute = False
                .StartInfo.RedirectStandardOutput = True
                .StartInfo.RedirectStandardError = True
                .StartInfo.CreateNoWindow = True
                .StartInfo.WindowStyle = ProcessWindowStyle.Hidden

                AddHandler .OutputDataReceived, AddressOf HelpOutputDataHandler

                .Start()

                .BeginOutputReadLine()

                '--wait for exiftool to finish and exit

                Do Until .HasExited
                    Thread.Sleep(20)
                Loop

                RemoveHandler .OutputDataReceived, AddressOf HelpOutputDataHandler

                .Close()

                _ExifToolHelpString = stdoutHelpString.ToString
            End With
        End If

        Return _ExifToolHelpString
    End Function

    Private Shared stdoutHelpString As New StringBuilder

    Private Shared Sub HelpOutputDataHandler(sender As Object, args As DataReceivedEventArgs)
        If args.Data IsNot Nothing Then

            '--handles each ReadLine

            '--args.data is a single line of the output, but does not end with a CRLF, so we need to add that

            stdoutHelpString.Append(args.Data)
            stdoutHelpString.Append(ControlChars.CrLf)
        End If
    End Sub

[Phil Harvey]

Great.  And thanks for posting the vb.net code.

- Phil