expand_file_name
expand_file_name (pathname)
This function returns the path name corresponding to pathname. Any environment variables in the string expression are expanded.
A leading ~ expands to the value of the HOME environment variable. If the HOME environment variable is not set, the ~ resolves to the value of the HOMEDRIVE and HOMEPATH environment variables (which are usually set on Windows). If neither HOME or HOMEPATH are set, the ~ is not substituted and will remain in the path.
Examples
$f = 'C:\source_files\graphics\home.tif'
g$example = expand_file_name($f)