Functions and positional parameters, SVR2 vs SVR3 ff.

Functions and positional parameters: SVR2 vs SVR3 ff.

The SVR2 variant of the Bourne shell introduced functions.
It was documented that:

    Execution

    [...]  The positional parameters $1, $2, .... are set to the
    arguments of the function.

So this behaviour

is not a bug,
and it's consistent, because functions modify the global environment also in any other aspect:
- current working directory
- variables
- error flag ("set -e")
- further function definitions

However, this behaviour is not intuitive when having background in other programming languages.

The behaviour was changed with the following SVR3 variant.

The decisions how to go on with SVR2 based shells were different now:

HP-UX always kept the SVR2 based shell and they never changed this behaviour.
Instead they added a note to the WARNING section of the manpage.
OFS1 always kept the SVR2 variant, too, but they did change the behaviour.
Interestingly, they wrongly still document the old behaviour until today.
In Version 8, the SVR2 variant was taken as code base for numerous further changes, mainly aiming towards a cleaner and more consistent design - and probably for this reason the behaviour of functions was not changed here.

There's also a thread with numerous different points of view on the issue, see <316526A3.2541@ats.nld.alcatel.nl> and ff., 04/96 starting in comp.unix.shell, comp.sys.hp.hpux, comp.sys.hp.apps, comp.unix.internals.