usr.bin/nohup/nohup.c

   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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#) Copyright (c) 1989, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)nohup.c  8.1 (Berkeley) 6/6/93
  31  * $FreeBSD: src/usr.bin/nohup/nohup.c,v 1.4.2.2 2001/08/02 01:45:45 obrien Exp $
  32  * $DragonFly: src/usr.bin/nohup/nohup.c,v 1.5 2004/12/22 00:12:30 liamfoy Exp $
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/stat.h>
  37
  38 #include <err.h>
  39 #include <errno.h>
  40 #include <fcntl.h>
  41 #include <signal.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45
  46 static void dofile(void);
  47 static void usage(void);
  48
  49 #define FILENAME        "nohup.out"
  50 /*
  51  * POSIX mandates that we exit with:
  52  * 126 - If the utility was found, but failed to execute.
  53  * 127 - If any other error occurred.
  54  */
  55 #define EXIT_NOEXEC     126
  56 #define EXIT_NOTFOUND   127
  57 #define EXIT_MISC       127
  58
  59 int
  60 main(int argc, char **argv)
  61 {
  62         int exit_status;
  63
  64         while (getopt(argc, argv, "") != -1)
  65                 usage();
  66         argc -= optind;
  67         argv += optind;
  68         if (argc < 1)
  69                 usage();
  70
  71         if (isatty(STDOUT_FILENO))
  72                 dofile();
  73         if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
  74                 /* may have just closed stderr */
  75                 err(EXIT_MISC, "%s", argv[0]);
  76
  77         signal(SIGHUP, SIG_IGN);
  78
  79         execvp(*argv, argv);
  80         exit_status = (errno == ENOENT) ? EXIT_NOTFOUND : EXIT_NOEXEC;
  81         err(exit_status, "%s", argv[0]);
  82 }
  83
  84 static void
  85 dofile(void)
  86 {
  87         int fd;
  88         char path[MAXPATHLEN];
  89         const char *p;
  90
  91         /*
  92          * POSIX mandates if the standard output is a terminal, the standard
  93          * output is appended to nohup.out in the working directory.  Failing
  94          * that, it will be appended to nohup.out in the directory obtained
  95          * from the HOME environment variable.  If file creation is required,
  96          * the mode_t is set to S_IRUSR | S_IWUSR.
  97          */
  98         p = FILENAME;
  99         fd = open(p, O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);
 100         if (fd != -1)
 101                 goto dupit;
 102         if ((p = getenv("HOME")) != NULL && *p != '\0' &&
 103             (size_t)snprintf(path, sizeof(path), "%s/%s", p, FILENAME) <
 104             sizeof(path)) {
 105                 fd = open(p = path, O_RDWR | O_CREAT | O_APPEND,
 106                     S_IRUSR | S_IWUSR);
 107                 if (fd != -1)
 108                         goto dupit;
 109         }
 110         errx(EXIT_MISC, "can't open a nohup.out file");
 111
 112 dupit:
 113         if (dup2(fd, STDOUT_FILENO) == -1)
 114                 err(EXIT_MISC, "dup2 failed");
 115         fprintf(stderr, "appending output to %s\n", p);
 116 }
 117
 118 static void
 119 usage(void)
 120 {
 121         fprintf(stderr, "usage: nohup [--] command [arguments]\n");
 122         exit(EXIT_MISC);
 123 }