/usr/lib/dag questions

[Guy Harris]

> I noticed an executable file in /usr/lib of our SYS V's called 'dag'
> that wasn't in the manuals. Maybe this stands for Data Access Graph?
> It seems to read c programs from stdin and reports to stdout the last
> values assigned to variables by the program by some ordering.
> The only option I could find was a -d# where # is a number, but this
> didn't alter the behavior of the program in any apparent way.
> 
> Does anyone know what /usr/lib/dag does? Can an ordinary user be able
> to put it to any use?

No, 'dag' stands for Douglas A. Gwyn; ask him whatever questions you have.
:-) :-) :-)

It actually stands, probably, for "directed acyclic graph", which is what
'dag' usually stands for in computer parlance.  (It's basically like a tree,
only you can have branches joining as well as splitting.)  As far as I know,
the only thing D. A. Gwyn had to do with it are putting it up under 4.2BSD
and possibly fixing bugs or running it through "lint", as part of the BRL
System V compatibility package.

It's a part of the "cflow" utility in System V, which prints out a control
flow graph of a C program, indicating what routines call other routines.  It
is *NOT* intended for use as a standalone program!  It is run by "cflow",
which is a shell script.

By and large, the answer to the question "Can an ordinary user be able to
put '/usr/lib/<something>' to any use?" is "no".  If it could be put to use,
it wouldn't be in "/usr/lib".   Programs in "/usr/lib" are generally either
components of utilities like "lint", or a compiler, or things like that,
where a "driver" program or shell script runs several "worker" programs, or
they are specialized system utilities like "sendmail".

	Guy Harris