Rename files starting with space

Hi,

I would like to rename all the files starting with a space into files starting with an underscore (leaving all other spaces).
For example:
" 1test file.txt" >> "_1test file.txt"

Is this possible?

Thanks in advance!

Replace "^ " (ie "^" plus space)
with "_"
use regular expressions

"^" signifies start of string so only a space at the beginning of a filename will be replaced.