st: sysdir set for do-files or datasets ?

[Misha Bonch-O <bontchos@email.unc.edu>]

With sysdir set, we can specify a personal  directory for ado-files, 
where Stata will look them up first.
Is it possible to do the same for do-files ?  Or for the datasets ?
I prefer to keep my datasets and do-files that I run in the different 
directories.
Therefore, if my current working directory is the one with the datasets, 
I always have to write a very long path to: do "longpath"a.do

Other way, of course, is to set current directory with do-files, but I 
will have to  write long path names when I use or save datasets.
Is there way to set up a default directory, where Stata starts looking 
for do-files or datasets ?
Thank you, for attention.
Misha Bonch-Osmolovski.
UNC-Chapel Hill. 

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