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1 ## Copyright (C) 1996 John W. Eaton |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## usage: [IN, OUT, PID] = popen2 (COMMAND, ARGS) |
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21 ## |
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22 ## Start a subprocess with two-way communication. COMMAND specifies |
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23 ## the name of the command to start. ARGS is an array of strings |
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24 ## containing options for COMMAND. IN and out are the file ids of the |
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25 ## input and streams for the subprocess, and PID is the process id of |
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26 ## the subprocess, or -1 if COMMAND could not be executed. |
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27 ## |
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28 ## Example: |
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29 ## |
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30 ## [in, out, pid] = popen2 ("sort", "-nr"); |
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31 ## fputs (in, "these\n"); |
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32 ## fputs (in, "are\n"); |
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33 ## fputs (in, "some\n"); |
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34 ## fputs (in, "strings\n"); |
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35 ## fclose (in); |
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36 ## while (isstr (s = fgets (out))) |
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37 ## fputs (stdout, s); |
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38 ## endwhile |
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39 ## fclose (out); |
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40 |
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41 function [in, out, pid] = popen2 (command, args) |
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42 |
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43 in = -1; |
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44 out = -1; |
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45 pid = -1; |
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46 |
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47 if (nargin == 1 || nargin == 2) |
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48 |
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49 if (nargin == 1) |
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50 args = ""; |
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51 endif |
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52 |
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53 if (isstr (command)) |
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54 |
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55 [stdin_pipe, stdin_status] = pipe (); |
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56 [stdout_pipe, stdout_status] = pipe (); |
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57 |
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58 if (stdin_status == 0 && stdout_status == 0) |
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59 |
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60 pid = fork (); |
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61 |
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62 if (pid == 0) |
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63 |
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64 fclose (stdin_pipe (2)); |
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65 fclose (stdout_pipe (1)); |
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66 |
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67 dup2 (stdin_pipe (1), stdin); |
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68 fclose (stdin_pipe (1)); |
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69 |
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70 dup2 (stdout_pipe (2), stdout); |
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71 fclose (stdout_pipe (2)); |
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72 |
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73 if (exec (command, args) < 0) |
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74 error ("popen2: unable to start process `%s'", command); |
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75 exit (0); |
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76 endif |
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77 |
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78 elseif (pid) |
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79 |
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80 fclose (stdin_pipe (1)); |
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81 fclose (stdout_pipe (2)); |
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82 |
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83 if (fcntl (stdout_pipe (1), __F_SETFL__, __O_NONBLOCK__) < 0) |
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84 error ("popen2: error setting file mode"); |
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85 else |
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86 in = stdin_pipe (2); |
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87 out = stdout_pipe (1); |
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88 endif |
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89 |
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90 elseif (pid < 0) |
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91 error ("popen2: fork failed -- unable to create child process"); |
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92 endif |
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93 else |
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94 error ("popen2: pipe creation failed"); |
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95 endif |
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96 else |
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97 error ("popen2: file name must be a string"); |
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98 endif |
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99 else |
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100 usage ("[in, out, pid] = popen2 (command, args)"); |
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101 endif |
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102 |
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103 endfunction |
