1 This file is trap.def, from which is created trap.c.
2 It implements the builtin "trap" in Bash.
4 Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
6 This file is part of GNU Bash, the Bourne Again SHell.
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 1, or (at your option) any later
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
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, 675 Mass Ave, Cambridge, MA 02139, USA.
25 $FUNCTION trap_builtin
26 $SHORT_DOC trap [arg] [signal_spec ...] or trap -l
27 The command ARG is to be read and executed when the shell receives
28 signal(s) SIGNAL_SPEC. If ARG is absent all specified signals are
29 reset to their original values. If ARG is the null string each
30 SIGNAL_SPEC is ignored by the shell and by the commands it invokes.
31 If a SIGNAL_SPEC is EXIT (0) the command ARG is executed on exit from
32 the shell. If a SIGNAL_SPEC is DEBUG, ARG is executed after every
33 command. If ARG is `-p' then the trap commands associated with
34 each SIGNAL_SPEC are displayed. If no arguments are supplied or if
35 only `-p' is given, trap prints the list of commands associated with
36 each signal number. Each SIGNAL_SPEC is either a signal name in <signal.h>
37 or a signal number. `trap -l' prints a list of signal names and their
38 corresponding numbers. Note that a signal can be sent to the shell
39 with "kill -signal $$".
44 #if defined (HAVE_UNISTD_H)
48 #include "../bashtypes.h"
51 #include "../bashansi.h"
56 #include "bashgetopt.h"
58 static int display_traps ();
62 trap <arg> <signal ...>
68 Set things up so that ARG is executed when SIGNAL(s) N is recieved.
69 If ARG is the empty string, then ignore the SIGNAL(s). If there is
70 no ARG, then set the trap for SIGNAL(s) to its original value. Just
71 plain "trap" means to print out the list of commands associated with
72 each signal number. Single arg of "-l" means list the signal names. */
74 /* Possible operations to perform on the list of signals.*/
75 #define SET 0 /* Set this signal to first_arg. */
76 #define REVERT 1 /* Revert to this signals original value. */
77 #define IGNORE 2 /* Ignore this signal. */
79 extern int interactive;
85 int list_signal_names, display, result, opt;
87 list_signal_names = display = 0;
88 result = EXECUTION_SUCCESS;
89 reset_internal_getopt ();
90 while ((opt = internal_getopt (list, "lp")) != -1)
107 if (list_signal_names)
108 return (display_signal_list ((WORD_LIST *)NULL, 1));
109 else if (display || list == 0)
110 return (display_traps (list));
117 first_arg = list->word->word;
118 if (first_arg && *first_arg && (*first_arg != '-' || first_arg[1]) &&
119 signal_object_p (first_arg))
124 if (*first_arg == '\0')
126 else if (first_arg[0] == '-' && !first_arg[1])
132 sig = decode_signal (list->word->word);
136 builtin_error ("%s: not a signal specification",
138 result = EXECUTION_FAILURE;
145 set_signal (sig, first_arg);
149 restore_default_signal (sig);
151 /* Signals that the shell treats specially need special
157 set_signal_handler (SIGINT, sigint_sighandler);
159 set_signal_handler (SIGINT, termination_unwind_protect);
163 /* Always ignore SIGQUIT. */
164 set_signal_handler (SIGQUIT, SIG_IGN);
167 #if defined (JOB_CONTROL)
171 #endif /* JOB_CONTROL */
173 set_signal_handler (sig, SIG_IGN);
198 if (p == (char *)DEFAULT_SIG)
201 t = (p == (char *)IGNORE_SIG) ? (char *)NULL : single_quote (p);
202 printf ("trap -- %s %s\n", t ? t : "''", signal_name (i));
215 for (i = 0; i <= NSIG; i++)
217 return (EXECUTION_SUCCESS);
220 for (result = EXECUTION_SUCCESS; list; list = list->next)
222 i = decode_signal (list->word->word);
225 result = EXECUTION_FAILURE;
226 builtin_error ("%s: not a signal specification", list->word->word);