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. 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  * @(#) Copyright (c) 1989, 1993 The Regents of the University of California.  All rights reserved.
  34  * @(#)nohup.c  8.1 (Berkeley) 6/6/93
  35  * $FreeBSD: src/usr.bin/nohup/nohup.c,v 1.4.2.2 2001/08/02 01:45:45 obrien Exp $
  36  * $DragonFly: src/usr.bin/nohup/nohup.c,v 1.5 2004/12/22 00:12:30 liamfoy Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/stat.h>
  41
  42 #include <err.h>
  43 #include <errno.h>
  44 #include <fcntl.h>
  45 #include <signal.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49
  50 static void dofile(void);
  51 static void usage(void);
  52
  53 #define FILENAME        "nohup.out"
  54 /*
  55  * POSIX mandates that we exit with:
  56  * 126 - If the utility was found, but failed to execute.
  57  * 127 - If any other error occurred.
  58  */
  59 #define EXIT_NOEXEC     126
  60 #define EXIT_NOTFOUND   127
  61 #define EXIT_MISC       127
  62
  63 int
  64 main(int argc, char **argv)
  65 {
  66         int exit_status;
  67
  68         while (getopt(argc, argv, "") != -1)
  69                 usage();
  70         argc -= optind;
  71         argv += optind;
  72         if (argc < 1)
  73                 usage();
  74
  75         if (isatty(STDOUT_FILENO))
  76                 dofile();
  77         if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1)
  78                 /* may have just closed stderr */
  79                 err(EXIT_MISC, "%s", argv[0]);
  80
  81         signal(SIGHUP, SIG_IGN);
  82
  83         execvp(*argv, argv);
  84         exit_status = (errno == ENOENT) ? EXIT_NOTFOUND : EXIT_NOEXEC;
  85         err(exit_status, "%s", argv[0]);
  86 }
  87
  88 static void
  89 dofile(void)
  90 {
  91         int fd;
  92         char path[MAXPATHLEN];
  93         const char *p;
  94
  95         /*
  96          * POSIX mandates if the standard output is a terminal, the standard
  97          * output is appended to nohup.out in the working directory.  Failing
  98          * that, it will be appended to nohup.out in the directory obtained
  99          * from the HOME environment variable.  If file creation is required,
 100          * the mode_t is set to S_IRUSR | S_IWUSR.
 101          */
 102         p = FILENAME;
 103         fd = open(p, O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);
 104         if (fd != -1)
 105                 goto dupit;
 106         if ((p = getenv("HOME")) != NULL && *p != '\0' &&
 107             (size_t)snprintf(path, sizeof(path), "%s/%s", p, FILENAME) <
 108             sizeof(path)) {
 109                 fd = open(p = path, O_RDWR | O_CREAT | O_APPEND,
 110                     S_IRUSR | S_IWUSR);
 111                 if (fd != -1)
 112                         goto dupit;
 113         }
 114         errx(EXIT_MISC, "can't open a nohup.out file");
 115
 116 dupit:
 117         if (dup2(fd, STDOUT_FILENO) == -1)
 118                 err(EXIT_MISC, "dup2 failed");
 119         fprintf(stderr, "appending output to %s\n", p);
 120 }
 121
 122 static void
 123 usage(void)
 124 {
 125         fprintf(stderr, "usage: nohup [--] command [arguments]\n");
 126         exit(EXIT_MISC);
 127 }