nohup.c revision 92921 
1/*
2 * Copyright (c) 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1989, 1993\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)nohup.c	8.1 (Berkeley) 6/6/93";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/usr.bin/nohup/nohup.c 92921 2002-03-22 01:33:25Z imp $";
46#endif /* not lint */
47
48#include <sys/param.h>
49#include <sys/stat.h>
50
51#include <err.h>
52#include <errno.h>
53#include <fcntl.h>
54#include <signal.h>
55#include <stdio.h>
56#include <stdlib.h>
57#include <string.h>
58#include <unistd.h>
59
60static void dofile(void);
61static void usage(void);
62
63#define	FILENAME	"nohup.out"
64/*
65 * POSIX mandates that we exit with:
66 * 126 - If the utility was found, but failed to execute.
67 * 127 - If any other error occurred.
68 */
69#define	EXIT_NOEXEC	126
70#define	EXIT_NOTFOUND	127
71#define	EXIT_MISC	127
72
73int
74main(argc, argv)
75	int argc;
76	char *argv[];
77{
78	int exit_status;
79
80	while (getopt(argc, argv, "") != -1)
81		usage();
82	argc -= optind;
83	argv += optind;
84	if (argc < 1)
85		usage();
86
87	if (isatty(STDOUT_FILENO))
88		dofile();
89	if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
90		/* may have just closed stderr */
91		err(EXIT_MISC, "%s", argv[0]);
92
93	(void)signal(SIGHUP, SIG_IGN);
94
95	execvp(*argv, argv);
96	exit_status = (errno == ENOENT) ? EXIT_NOTFOUND : EXIT_NOEXEC;
97	err(exit_status, "%s", argv[0]);
98}
99
100static void
101dofile()
102{
103	int fd;
104	char path[MAXPATHLEN];
105	const char *p;
106
107	/*
108	 * POSIX mandates if the standard output is a terminal, the standard
109	 * output is appended to nohup.out in the working directory.  Failing
110	 * that, it will be appended to nohup.out in the directory obtained
111	 * from the HOME environment variable.  If file creation is required,
112	 * the mode_t is set to S_IRUSR | S_IWUSR.
113	 */
114	p = FILENAME;
115	fd = open(p, O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);
116	if (fd != -1)
117		goto dupit;
118	if ((p = getenv("HOME")) != NULL && *p != '\0' &&
119	    (size_t)snprintf(path, sizeof(path), "%s/%s", p, FILENAME) <
120	    sizeof(path)) {
121		fd = open(p = path, O_RDWR | O_CREAT | O_APPEND,
122		    S_IRUSR | S_IWUSR);
123		if (fd != -1)
124			goto dupit;
125	}
126	errx(EXIT_MISC, "can't open a nohup.out file");
127
128dupit:
129	if (dup2(fd, STDOUT_FILENO) == -1)
130		err(EXIT_MISC, NULL);
131	(void)fprintf(stderr, "appending output to %s\n", p);
132}
133
134static void
135usage()
136{
137	(void)fprintf(stderr, "usage: nohup [--] command [arguments]\n");
138	exit(EXIT_MISC);
139}
140