[Charlug] command line help please

[Mark]

Hi there, I'm trying to think of an easy way to do this, basically I 
have a bunch of files with this naming format:

filename_YYYYMMDDhhmm.ext

I want to extract the YYYYMMDDhhmm part of each filename to use with 
'touch' to change the datestamp:
eg:
touch filename_200912220115.jpg -t 200912220115

Can someone suggest a way to automate this? I would like to be able to 
process a whole directory at once, preferably a one-line command using 
pipes.

Thanks,
Mark