sh: Add kill builtin.

This allows specifying a %job (which is equivalent to the corresponding
process group).

Additionally, it improves reliability of kill from sh in high-load
situations and ensures "kill" finds the correct utility regardless of PATH,
as required by POSIX (unless the undocumented %builtin mechanism is used).

Side effect: fatal errors (any error other than kill(2) failure) now return
exit status 2 instead of 1. (This is consistent with other sh builtins, but
not in NetBSD.)

Code size increases about 1K on i386.

Obtained from:	NetBSD

1 files changed, 8 insertions, 0 deletions

diff --git a/bin/sh/jobs.c b/bin/sh/jobs.c
index 6a781ea..fda167b 100644
--- a/bin/sh/jobs.c
+++ b/bin/sh/jobs.c
@@ -632,6 +632,14 @@ currentjob:	if ((jp = getcurjob(NULL)) == NULL)
 }
 
 
+pid_t
+getjobpgrp(char *name)
+{
+	struct job *jp;
+
+	jp = getjob(name);
+	return -jp->ps[0].pid;
+}
 
 /*
  * Return a new job structure,