builtins/fg_bg.def

   1 This file is fg_bg.def, from which is created fg_bg.c.
   2 It implements the builtins "bg" and "fg" in Bash.
   3
   4 Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Bash, the Bourne Again SHell.
   7
   8 Bash is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with Bash; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
  21
  22 $PRODUCES fg_bg.c
  23
  24 $BUILTIN fg
  25 $FUNCTION fg_builtin
  26 $DEPENDS_ON JOB_CONTROL
  27 $SHORT_DOC fg [job_spec]
  28 Place JOB_SPEC in the foreground, and make it the current job.  If
  29 JOB_SPEC is not present, the shell's notion of the current job is
  30 used.
  31 $END
  32
  33 #include <config.h>
  34
  35 #include "../bashtypes.h"
  36 #include <signal.h>
  37
  38 #if defined (HAVE_UNISTD_H)
  39 #  include <unistd.h>
  40 #endif
  41
  42 #include "../shell.h"
  43 #include "../jobs.h"
  44 #include "common.h"
  45
  46 #if defined (JOB_CONTROL)
  47 extern char *this_command_name;
  48
  49 static int fg_bg __P((WORD_LIST *, int));
  50
  51 /* How to bring a job into the foreground. */
  52 int
  53 fg_builtin (list)
  54      WORD_LIST *list;
  55 {
  56   int fg_bit;
  57   register WORD_LIST *t;
  58
  59   if (job_control == 0)
  60     {
  61       builtin_error ("no job control");
  62       return (EXECUTION_FAILURE);
  63     }
  64
  65   if (no_options (list))
  66     return (EX_USAGE);
  67
  68   /* If the last arg on the line is '&', then start this job in the
  69      background.  Else, fg the job. */
  70   for (t = list; t && t->next; t = t->next)
  71     ;
  72   fg_bit = (t && t->word->word[0] == '&' && t->word->word[1] == '\0') == 0;
  73
  74   return (fg_bg (list, fg_bit));
  75 }
  76 #endif /* JOB_CONTROL */
  77
  78 $BUILTIN bg
  79 $FUNCTION bg_builtin
  80 $DEPENDS_ON JOB_CONTROL
  81 $SHORT_DOC bg [job_spec]
  82 Place JOB_SPEC in the background, as if it had been started with
  83 `&'.  If JOB_SPEC is not present, the shell's notion of the current
  84 job is used.
  85 $END
  86
  87 #if defined (JOB_CONTROL)
  88 /* How to put a job into the background. */
  89 int
  90 bg_builtin (list)
  91      WORD_LIST *list;
  92 {
  93   if (job_control == 0)
  94     {
  95       builtin_error ("no job control");
  96       return (EXECUTION_FAILURE);
  97     }
  98
  99   if (no_options (list))
 100     return (EX_USAGE);
 101
 102   return (fg_bg (list, 0));
 103 }
 104
 105 /* How to put a job into the foreground/background. */
 106 static int
 107 fg_bg (list, foreground)
 108      WORD_LIST *list;
 109      int foreground;
 110 {
 111   sigset_t set, oset;
 112   int job, status, old_async_pid;
 113
 114   BLOCK_CHILD (set, oset);
 115   job = get_job_spec (list);
 116
 117   if (job < 0 || job >= job_slots || jobs[job] == 0)
 118     {
 119       if (job != DUP_JOB)
 120         builtin_error ("%s: no such job", list ? list->word->word : "current");
 121
 122       goto failure;
 123     }
 124
 125   /* Or if jobs[job]->pgrp == shell_pgrp. */
 126   if (IS_JOBCONTROL (job) == 0)
 127     {
 128       builtin_error ("job %%%d started without job control", job + 1);
 129       goto failure;
 130     }
 131
 132   if (foreground == 0)
 133     {
 134       old_async_pid = last_asynchronous_pid;
 135       last_asynchronous_pid = jobs[job]->pgrp;  /* As per Posix.2 5.4.2 */
 136     }
 137
 138   status = start_job (job, foreground);
 139
 140   if (status >= 0)
 141     {
 142     /* win: */
 143       UNBLOCK_CHILD (oset);
 144       return (status);
 145     }
 146   else
 147     {
 148       if (foreground == 0)
 149         last_asynchronous_pid = old_async_pid;
 150
 151     failure:
 152       UNBLOCK_CHILD (oset);
 153       return (EXECUTION_FAILURE);
 154     }
 155 }
 156 #endif /* JOB_CONTROL */