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This file is fg_bg.def, from which is created fg_bg.c.
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It implements the builtins "bg" and "fg" in Bash.
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Copyright (C) 1987-2009 Free Software Foundation, Inc.
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This file is part of GNU Bash, the Bourne Again SHell.
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Bash is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Bash is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Bash. If not, see <http://www.gnu.org/licenses/>.
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$DEPENDS_ON JOB_CONTROL
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$SHORT_DOC fg [job_spec]
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Move job to the foreground.
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Place the job identified by JOB_SPEC in the foreground, making it the
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current job. If JOB_SPEC is not present, the shell's notion of the
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Status of command placed in foreground, or failure if an error occurs.
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#include "../bashtypes.h"
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#if defined (HAVE_UNISTD_H)
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#include "../bashintl.h"
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#include "bashgetopt.h"
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#if defined (JOB_CONTROL)
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extern char *this_command_name;
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static int fg_bg __P((WORD_LIST *, int));
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/* How to bring a job into the foreground. */
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register WORD_LIST *t;
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sh_nojobs ((char *)NULL);
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return (EXECUTION_FAILURE);
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if (no_options (list))
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/* If the last arg on the line is '&', then start this job in the
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background. Else, fg the job. */
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for (t = list; t && t->next; t = t->next)
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fg_bit = (t && t->word->word[0] == '&' && t->word->word[1] == '\0') == 0;
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return (fg_bg (list, fg_bit));
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#endif /* JOB_CONTROL */
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$DEPENDS_ON JOB_CONTROL
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$SHORT_DOC bg [job_spec ...]
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Move jobs to the background.
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Place the jobs identified by each JOB_SPEC in the background, as if they
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had been started with `&'. If JOB_SPEC is not present, the shell's notion
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of the current job is used.
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Returns success unless job control is not enabled or an error occurs.
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#if defined (JOB_CONTROL)
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/* How to put a job into the background. */
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if (job_control == 0)
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sh_nojobs ((char *)NULL);
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return (EXECUTION_FAILURE);
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if (no_options (list))
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/* This relies on the fact that fg_bg() takes a WORD_LIST *, but only acts
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on the first member (if any) of that list. */
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r = EXECUTION_SUCCESS;
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if (fg_bg (list, 0) == EXECUTION_FAILURE)
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r = EXECUTION_FAILURE;
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/* How to put a job into the foreground/background. */
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fg_bg (list, foreground)
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int job, status, old_async_pid;
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BLOCK_CHILD (set, oset);
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job = get_job_spec (list);
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if (INVALID_JOB (job))
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sh_badjob (list ? list->word->word : _("current"));
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j = get_job_by_jid (job);
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/* Or if j->pgrp == shell_pgrp. */
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if (IS_JOBCONTROL (job) == 0)
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builtin_error (_("job %d started without job control"), job + 1);
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old_async_pid = last_asynchronous_pid;
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last_asynchronous_pid = j->pgrp; /* As per Posix.2 5.4.2 */
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status = start_job (job, foreground);
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UNBLOCK_CHILD (oset);
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return (foreground ? status : EXECUTION_SUCCESS);
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last_asynchronous_pid = old_async_pid;
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UNBLOCK_CHILD (oset);
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return (EXECUTION_FAILURE);
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#endif /* JOB_CONTROL */