add nohup

Makefile

@@ -7,9 +7,11 @@ LIB = \
 	util/concat.o    \
 	util/enmasse.o   \
 	util/eprintf.o   \
+	util/enprintf.o  \
 	util/estrtol.o   \
 	util/putword.o   \
 	util/recurse.o   \
+	util/venprintf.o
 
 SRC = \
 	basename.c \
@@ -31,6 +33,7 @@ SRC = \
 	mkdir.c    \
 	mkfifo.c   \
 	nl.c       \
+	nohup.c    \
 	pwd.c      \
 	rm.c       \
 	sleep.c    \

nohup.1

@@ -0,0 +1,15 @@
+.TH NOHUP 1 sbase\-VERSION
+.SH NAME
+nohup \- run a command immune to hangups
+.SH SYNOPSIS
+.B nohup
+.I command
+.RI [ argument ...]
+.SH DESCRIPTION
+.B nohup
+runs the given command with the SIGHUP signal set to be ignored.  If stdout is a
+tty, it is appended to
+.I nohup.out
+in the current working directory; if stderr is a tty, it is redirected to stdout.
+.SH SEE ALSO
+.IR signal (7)

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;
+}

util.h

@@ -5,6 +5,7 @@
 char *agetcwd(void);
 void enmasse(int, char **, int (*)(const char *, const char *));
 void eprintf(const char *, ...);
+void enprintf(int, const char *, ...);
 long estrtol(const char *, int);
 void putword(const char *);
 void recurse(const char *, void (*)(const char *));

util/enprintf.c

@@ -0,0 +1,15 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdarg.h>
+#include "../util.h"
+
+extern void venprintf(int, const char *, va_list);
+
+void
+enprintf(int status, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	venprintf(status, fmt, ap);
+	va_end(ap);
+}

util/eprintf.c

@@ -1,22 +1,16 @@
 /* See LICENSE file for copyright and license details. */
 #include <stdarg.h>
-#include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 #include "../util.h"
 
+extern void venprintf(int, const char *, va_list);
+
 void
 eprintf(const char *fmt, ...)
 {
 	va_list ap;
 
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	venprintf(EXIT_FAILURE, fmt, ap);
 	va_end(ap);
-
-	if(fmt[0] && fmt[strlen(fmt)-1] == ':') {
-		fputc(' ', stderr);
-		perror(NULL);
-	}
-	exit(EXIT_FAILURE);
 }

util/venprintf.c

@@ -0,0 +1,18 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "../util.h"
+
+void
+venprintf(int status, const char *fmt, va_list ap)
+{
+	vfprintf(stderr, fmt, ap);
+
+	if(fmt[0] && fmt[strlen(fmt)-1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	}
+	exit(status);
+}