61 lines
1.2 KiB
Perl
61 lines
1.2 KiB
Perl
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/* $Id$
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Part of SWI-Prolog
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Author: Jan Wielemaker
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E-mail: jan@swi.psy.uva.nl
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WWW: http://www.swi.psy.uva.nl/projects/SWI-Prolog/
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Copying: GPL-2. See the file COPYING or http://www.gnu.org
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Copyright (C) 1990-2000 SWI, University of Amsterdam. All rights reserved.
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*/
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:- module(subcommand,
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[ pipe_through_command/3 % +Command, +In, -Out
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]).
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:- use_module(library(unix)).
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% pipe_through_command(+Command, +In, -Out)
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%
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% Pipe text In through command Command and put the output of command
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% in Out.
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%
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% Example:
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%
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% ?- pipe_through_command(tr('a-z', 'A-Z'), hello, X)
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%
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% X = 'HELLO'
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pipe_through_command(Command, In, Out) :-
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pipe(ChildIn, MeOut),
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pipe(MeIn, ChildOut),
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fork(Pid),
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( Pid == child,
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close(MeOut),
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close(MeIn),
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dup(ChildIn, 0),
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dup(ChildOut, 1),
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close(ChildIn),
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close(ChildOut),
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exec(Command)
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; close(ChildIn),
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close(ChildOut),
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write(MeOut, In),
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close(MeOut),
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read_input(MeIn, Out),
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close(MeIn),
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wait(Pid, _Status) % avoid zombi
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).
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read_input(In, Atom) :-
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get_code(In, C0),
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read_input(C0, In, Codes),
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atom_codes(Atom, Codes).
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read_input(-1, _, []) :- !.
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read_input(C, In, [C|T]) :-
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get_code(In, C1),
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read_input(C1, In, T).
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