Improve -hosts robustness.

[trasz]

Summary

Make the autofs(5) -hosts map more robust, primarily to make it correctly
handle NFS shares containing whitespace. This also adds the -E parameter
to showmount(8).

[trasz]

This should fix PR 207596.

[jhibbits]

Works for my use case, thanks!

[wblock]

usr.bin/showmount/showmount.8

80

As used, a colon would be appropriate instead of the dash. But this can be simpler as two sentences: (wrapping approximate)

exports list in a script-friendly format.
Client addresses and the header are not shown, and special
characters are escaped.

[trasz]

Improve the manual page.

[emaste]

Should you handle invocation with both -E and -e explicitly?

[trasz]

Well, other options for showmount are effectively OR-ed... Or perhaps your suggestion is to add eg a -c options that is a modifier for -e, that makes it output script-friendly output instead of the usual?

[wblock]

Works for me!

[emaste]

In D5649#120966, @trasz wrote:

Well, other options for showmount are effectively OR-ed... Or perhaps your suggestion is to add eg a -c options that is a modifier for -e, that makes it output script-friendly output instead of the usual?

I think other options for showmount don't conflict with each other in the same way; passing both -e and -E here seems like it would would produce nonsensical output. I think it should either allow only one of -e and -E or the script mode should be a separate option like the -c you suggest.

[trasz]

Make the -E option conflict with all the others.