Out of descriptors, out of luck?

[Guy Harris]

>Many modern Unix systems support the setrlimit().  If the man page for
>setrlimit() says that it supports RLIMIT_NOFILE, then you can up the
>limit for the number of open files. Sun O/S >=4.0 and HP-UX >=8.0 are
>examples of two operating systems which support this facility.

HP-UX >= 8.0 may be a UNIX flavor that supports RLIMIT_NOFILE, but SunOS
>= 4.0 and < 4.1 is *NOT* an example of such a system - that showed up
in 4.1, not in 4.0.

System V Release 4 is another example of a UNIX flavor that supports
RLIMIT_NOFILE.  It shouldn't be too surprising that SunOS 4.1 and S5R4
do that the same way; however, the fact that an organization not in the
S5R4 camp followed in Sun's and AT&T's footsteps, rather than inventing
something different but not better, is somewhat refreshing - perhaps
there's hope for the UNIX community yet. :-)

Note that you will probably only be able to raise the soft limit for
RLIMIT_NOFILE (which, at least in SunOS 4.1 and S5R4, specifies how many
new file descriptors you can get) to the hard limit; you may not be able
to affect the hard limit at all.