Add an -a flag to getconf.

[jhb]

Summary

When -a is specified, the name and value of all system or path configuration
values is reported to standard output.

Linux's getconf supports -a, but only for system variables according to the
manual page.

[kib]

usr.bin/getconf/getconf.c

213 ↗

(On Diff #33082)

Why err() there, while other do_oneXXX() only warn() about error ? Is this for situations like ENOENT where the path is nonexistent ? I am not sure that other situations are impossible in principle where some parameter gives !EINVAL error.

IMO user deserves the fallout there.

usr.bin/getconf/pathconf.gperf

78 ↗

(On Diff #33082)

I would prefer to have the multi-line loop body braced.

[jhb]

usr.bin/getconf/getconf.c

213 ↗

(On Diff #33082)

Yes, the idea was to die once for ENOENT, but it is perhaps a bit fragile, so warn() is ok.

[jhb]

• Use warn() for errors from pathconf().
• Add braces in foreach routines.