AutoCAD - can you make a field to show only part of the filename?

[draftorb]

Basically we set up our file names with a # and the title of the drawing. I want to create a field that only shows the number thats in the file name.

Example: 

if the filename is "10101template.dwg", i  only want the 10101 to show up in my field.

is there a diesel expression or something along those lines that would chose only the first 5 characters in the file name? (our job numbers are 5 #'s long and are the beginning portion of the filename).

if not, is there an expression that would show all numbers in the file name?

I realize there are a few simliar posts, but I haven't found exactly what i am trying to do, but if i do find a solution elsewhere, i will post it here. 

Thank you,

[ The subject line of this post has been edited to include the product name by @handjonathan ]

[draftorb · Accepted solution]

doubt anyone will read this, since i solved my own problem very shortly, but if you're curious, the solution is the diesel expression:

$(substr,$(getvar,dwgname),1, 5)

The 1 means the first character of the field.

Then 5 obviously means the 5th character. 🙂

[jagostinhoCT]

This was exactly what I was looking for!

Very useful.

Thanks for posting the solution.

[esaldana]

Thanking you, just few years later 🙂

[fstechUWW4U]

Still useful!