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nohup.c revision 1.5 
      1 /*
      2  * Copyright (c) 1989 The Regents of the University of California.
      3  * 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
     35 char copyright[] =
     36 "@(#) Copyright (c) 1989 The Regents of the University of California.\n\
     37  All rights reserved.\n";
     38 #endif /* not lint */
     39 
     40 #ifndef lint
     41 /*static char sccsid[] = "from: @(#)nohup.c	5.4 (Berkeley) 6/1/90";*/
     42 static char rcsid[] = "$Id: nohup.c,v 1.5 1995/06/27 00:20:24 jtc Exp $";
     43 #endif /* not lint */
     44 
     45 #include <sys/param.h>
     46 #include <sys/file.h>
     47 #include <sys/stat.h>
     48 #include <fcntl.h>
     49 #include <unistd.h>
     50 #include <signal.h>
     51 #include <stdio.h>
     52 #include <stdlib.h>
     53 #include <string.h>
     54 #include <errno.h>
     55 
     56 static void dofile();
     57 static void usage();
     58 
     59 /* nohup shall exit with one of the following values:
     60    126 - The utility was found but could not be invoked.
     61    127 - An error occured in the nohup utility, or the utility could
     62          not be found. */
     63 #define EXIT_NOEXEC	126
     64 #define EXIT_NOTFOUND	127
     65 #define EXIT_MISC	127
     66 
     67 int
     68 main(argc, argv)
     69 	int argc;
     70 	char **argv;
     71 {
     72 	int exit_status;
     73 
     74 	if (argc < 2)
     75 		usage();
     76 
     77 	if (isatty(STDOUT_FILENO))
     78 		dofile();
     79 	if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1) {
     80 		/* may have just closed stderr */
     81 		(void)fprintf(stdin, "nohup: %s\n", strerror(errno));
     82 		exit(EXIT_MISC);
     83 	}
     84 
     85 	/* The nohup utility shall take the standard action for all signals
     86 	   except that SIGHUP shall be ignored. */
     87 	(void)signal(SIGHUP, SIG_IGN);
     88 
     89 	execvp(argv[1], &argv[1]);
     90 	exit_status = (errno = ENOENT) ? EXIT_NOTFOUND : EXIT_NOEXEC;
     91 	(void)fprintf(stderr, "nohup: %s: %s\n", argv[1], strerror(errno));
     92 	exit(exit_status);
     93 }
     94 
     95 static void
     96 dofile()
     97 {
     98 	int fd;
     99 	char *p, path[MAXPATHLEN];
    100 
    101 	/* If the standard output is a terminal, all output written to
    102 	   its standard output shall be appended to the end of the file
    103 	   nohup.out in the current directory.  If nohup.out cannot be
    104 	   created or opened for appending, the output shall be appended
    105 	   to the end of the file nohup.out in the directory specified
    106 	   by the HOME environment variable.
    107 
    108 	   If a file is created, the file's permission bits shall be
    109 	   set to S_IRUSR | S_IWUSR. */
    110 #define	FILENAME	"nohup.out"
    111 	p = FILENAME;
    112 	if ((fd = open(p, O_RDWR|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR)) >= 0)
    113 		goto dupit;
    114 	if ((p = getenv("HOME")) != NULL) {
    115 		(void)strcpy(path, p);
    116 		(void)strcat(path, "/");
    117 		(void)strcat(path, FILENAME);
    118 		if ((fd = open(p = path, O_RDWR|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR)) >= 0)
    119 			goto dupit;
    120 	}
    121 	(void)fprintf(stderr, "nohup: can't open a nohup.out file.\n");
    122 	exit(EXIT_MISC);
    123 
    124 dupit:	(void)lseek(fd, 0L, SEEK_END);
    125 	if (dup2(fd, STDOUT_FILENO) == -1) {
    126 		(void)fprintf(stderr, "nohup: %s\n", strerror(errno));
    127 		exit(EXIT_MISC);
    128 	}
    129 	(void)fprintf(stderr, "sending output to %s\n", p);
    130 }
    131 
    132 static void
    133 usage()
    134 {
    135 	(void)fprintf(stderr, "usage: nohup command\n");
    136 	exit(EXIT_MISC);
    137 }
    138