add nohup

nohup.c

@@ -0,0 +1,40 @@
+/* See LICENSE file for copyright and license details. */
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include "util.h"
+
+enum { Error = 127, Found = 126 };
+
+int
+main(int argc, char *argv[])
+{
+	int fd;
+	struct sigaction sa;
+
+	if(getopt(argc, argv, "") != -1)
+		exit(Error);
+	if(optind == argc)
+		enprintf(Error, "usage: %s command [argument...]\n", argv[0]);
+
+	sa.sa_handler = SIG_IGN;
+	if(sigaction(SIGHUP, &sa, NULL) == -1)
+		enprintf(Error, "sigaction HUP:");
+	if(isatty(STDOUT_FILENO)) {
+		if((fd = open("nohup.out", O_APPEND|O_CREAT, S_IRUSR|S_IWUSR)) == -1)
+			enprintf(Error, "open nohup.out:");
+		if(dup2(fd, STDOUT_FILENO) == -1)
+			enprintf(Error, "dup2:");
+		close(fd);
+	}
+	if(isatty(STDERR_FILENO))
+		if(dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
+			enprintf(Error, "dup2:");
+
+	execvp(argv[optind], &argv[optind]);
+	enprintf(errno == ENOENT ? Error : Found, "exec %s:", argv[optind]);
+	return Error;
+}