The majority of the systems define PRIO_MAX and PRIO_MIN,
but there is an obscure system, whose name I am not going
to tell, where they were not defined.
Quoting POSIX[0]:
"Care should be taken, also, to call _exit() rather than exit() if exec cannot be used, since
exit() flushes and closes standard I/O channels, thereby damaging the parent process' standard
I/O data structures. (Even with fork(), it is wrong to call exit(), since buffered data would
then be flushed twice.)"
[0]: http://pubs.opengroup.org/onlinepubs/009695399/functions/vfork.html
1) val is sufficient as "int" (read the standard)
2) BUGFIX: If getpriority fails, it returns -1 and sets errno.
Previously, it would correctly catch the errno but not take
care of the fact that by then val has been decremented by 1.
Only change val if the getpriority-call has been successful.
3) Add LIMIT()-macro from st to increase readability.
4) setpriority returns < 0 on failure
5) Remove bikeshedding-comment. Read the standard if you wonder.
6) return-value trick from env(1)
This commit adds the renice command and its man page,
it also introduces some fixes:
* Makes nice command more solid, it also makes it respect POSIX return values.
* Fixes estrtol, which produced a misleading error on out of range errors.
* Fixes chgrp.1 NAME section.
Signed-off-by: Christoph Lohmann <20h@r-36.net>
