append, don't truncate the nohup.out file

[unix-history] / usr / src / usr.bin / nohup / nohup.c

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)nohup.c     5.2 (Berkeley) %G%";
#endif /* not lint */

#include <sys/param.h>
#include <sys/signal.h>
#include <sys/file.h>
#include <unistd.h>
#include <stdio.h>

main(argc, argv)
       int argc;
       char **argv;
{
       extern int errno;
       char *strerror();

       if (argc < 2)
               usage();

       if (isatty(STDOUT_FILENO))
               dofile();
       if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1) {
               /* may have just closed stderr */
               (void)fprintf(stdin, "nohup: %s\n", strerror(errno));
               exit(1);
       }

       (void)signal(SIGHUP, SIG_IGN);
       (void)signal(SIGQUIT, SIG_IGN);

       execvp(argv[1], &argv[1]);
       (void)fprintf(stderr,
           "nohup: %s: %s\n", argv[1], strerror(errno));
       exit(1);
}

dofile()
{
       int fd;
       char *p, path[MAXPATHLEN];
       off_t lseek();
       char *getenv(), *strcpy(), *strcat(), *strerror();

#define FILENAME        "nohup.out"
       p = FILENAME;
       if ((fd = open(p, O_RDWR|O_CREAT, 0600)) >= 0)
               goto dupit;
       if (p = getenv("HOME")) {
               (void)strcpy(path, p);
               (void)strcat(path, "/");
               (void)strcat(path, FILENAME);
               if ((fd = open(p = path, O_RDWR|O_CREAT, 0600)) >= 0)
                       goto dupit;
       }
       (void)fprintf(stderr, "nohup: can't open a nohup.out file.\n");
       exit(1);

dupit:  (void)lseek(fd, 0L, SEEK_END);
       if (dup2(fd, STDOUT_FILENO) == -1) {
               (void)fprintf(stderr, "nohup: %s\n", strerror(errno));
               exit(1);
       }
       (void)fprintf(stderr, "sending output to %s\n", p);
}

usage()
{
       (void)fprintf(stderr, "usage: nohup command\n");
       exit(1);
}