add kill, thanks rob

Makefile

@@ -22,6 +22,7 @@ SRC = \
 	fold.c     \
 	grep.c     \
 	head.c     \
+	kill.c     \
 	ln.c       \
 	ls.c       \
 	mkdir.c    \

kill.1

@@ -0,0 +1,18 @@
+.TH KILL 1 sbase\-VERSION
+.SH NAME
+KILL \- compare two files
+.SH SYNOPSIS
+.B kill
+.RB [ \-s ]
+.RI [ pid ...]
+.SH DESCRIPTION
+.B kill
+sends a
+.I TERM
+signal to the given processes.
+.SH OPTIONS
+.TP
+.BI \-s " signal"
+sends the named signal.
+.SH SEE ALSO
+.IR kill (2)

kill.c

@@ -0,0 +1,50 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdlib.h>
+#include <signal.h>
+#include <strings.h>
+#include <unistd.h>
+#include "util.h"
+
+#define LEN(x) (sizeof (x) / sizeof *(x))
+
+struct {
+	const char *name;
+	int sig;
+} sigs[] = {
+#define SIG(n) { #n, SIG##n }
+	SIG(ABRT), SIG(ALRM), SIG(BUS),  SIG(CHLD), SIG(CONT), SIG(FPE),  SIG(HUP),
+	SIG(ILL),  SIG(INT),  SIG(KILL), SIG(PIPE), SIG(QUIT), SIG(SEGV), SIG(STOP),
+	SIG(TERM), SIG(TSTP), SIG(TTIN), SIG(TTOU), SIG(USR1), SIG(USR2), SIG(URG),
+#undef SIG
+};
+
+int
+main(int argc, char *argv[])
+{
+	char c, *end;
+	int i, sig = SIGTERM;
+	pid_t pid;
+
+	while((c = getopt(argc, argv, "s:")) != -1)
+		switch(c) {
+		case 's':
+			for(i = 0; i < LEN(sigs); i++)
+				if(!strcasecmp(optarg, sigs[i].name)) {
+					sig = sigs[i].sig;
+					break;
+				}
+			if(i == LEN(sigs))
+				eprintf("%s: unknown signal\n", optarg);
+			break;
+		default:
+			exit(EXIT_FAILURE);
+		}
+	for(; optind < argc; optind++) {
+		pid = strtol(argv[optind], &end, 0);
+		if(*end != '\0')
+			eprintf("%s: not a number\n", argv[optind]);
+		if(kill(pid, sig) == -1)
+			eprintf("kill %d:", pid);
+	}
+	return EXIT_SUCCESS;
+}