st: skip functions containing missing variables?

[Michael Costello <michaelavcostello@gmail.com>]

Dear awesome Statalisters,

I have about 25 databases with similar (but not exactly the same)
variable lists.  I want to "clean" them up by adjusting labels,
formats, etc.  Is there a way to have stata simply skip an absent
variable so taht I can run the same .do file on every database?  For
example:

one.dta varlist: gender age date grade speed
two.dta varlist: gender date grade speed

Since age is missing from the second database if I run a script saying
"label variable age "How old is the student?" " stata would stop
running because of an error.  Or, if I tried to change the order of
the (present) variables, it would have an error when it came to the
missing age variable.

So is there a way I can avoid this error?  Is there some prefix that
says: Do only when variables are present?

-Michael
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