- Don't assume environment variable HOME is not NULL.
o Integrate standards compliance from NetBSD.
- Allow -- before the command.
- Blocking SIGQUIT isn't standards compliant.
- Proper exit(3) levels.
- Actually append to nohup.out (as documented and required
by standard) instead of clobbering it.
o Remove some FreeBSD specific access(2) cruft (relating to
incorrect appending).
o Document the fact that two or more instances of nohup can
append to the same file.
o Constify; Staticize functions; Set WARNS?=2
Reviewed by: bde
Approved by: des
Obtained from: NetBSD, OpenBSD
MFC after: 9 days
