builtins/echo.def

   1 This file is echo.def, from which is created echo.c.
   2 It implements the builtin "echo" in Bash.
   3
   4 Copyright (C) 1987-2002 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 echo.c
  23 #include <config.h>
  24
  25 #if defined (HAVE_UNISTD_H)
  26 #  include <unistd.h>
  27 #endif
  28
  29 #include "../bashansi.h"
  30
  31 #include <stdio.h>
  32 #include "../shell.h"
  33
  34 $BUILTIN echo
  35 $FUNCTION echo_builtin
  36 $DEPENDS_ON V9_ECHO
  37 $SHORT_DOC echo [-neE] [arg ...]
  38 Output the ARGs.  If -n is specified, the trailing newline is
  39 suppressed.  If the -e option is given, interpretation of the
  40 following backslash-escaped characters is turned on:
  41         \a      alert (bell)
  42         \b      backspace
  43         \c      suppress trailing newline
  44         \E      escape character
  45         \f      form feed
  46         \n      new line
  47         \r      carriage return
  48         \t      horizontal tab
  49         \v      vertical tab
  50         \\      backslash
  51         \num    the character whose ASCII code is NUM (octal).
  52
  53 You can explicitly turn off the interpretation of the above characters
  54 with the -E option.
  55 $END
  56
  57 $BUILTIN echo
  58 $FUNCTION echo_builtin
  59 $DEPENDS_ON !V9_ECHO
  60 $SHORT_DOC echo [-n] [arg ...]
  61 Output the ARGs.  If -n is specified, the trailing newline is suppressed.
  62 $END
  63
  64 #if defined (V9_ECHO)
  65 #  define VALID_ECHO_OPTIONS "neE"
  66 #else /* !V9_ECHO */
  67 #  define VALID_ECHO_OPTIONS "n"
  68 #endif /* !V9_ECHO */
  69
  70 /* System V machines already have a /bin/sh with a v9 behaviour.  We
  71    give Bash the identical behaviour for these machines so that the
  72    existing system shells won't barf.  Regrettably, the SUS v2 has
  73    standardized the Sys V echo behavior.  This variable is external
  74    so that we can have a `shopt' variable to control it at runtime. */
  75 #if defined (DEFAULT_ECHO_TO_XPG)
  76 int xpg_echo = 1;
  77 #else
  78 int xpg_echo = 0;
  79 #endif /* DEFAULT_ECHO_TO_XPG */
  80
  81 /* Print the words in LIST to standard output.  If the first word is
  82    `-n', then don't print a trailing newline.  We also support the
  83    echo syntax from Version 9 Unix systems. */
  84 int
  85 echo_builtin (list)
  86      WORD_LIST *list;
  87 {
  88   int display_return, do_v9, i, len;
  89   char *temp, *s;
  90
  91   do_v9 = xpg_echo;
  92   display_return = 1;
  93
  94   for (; list && (temp = list->word->word) && *temp == '-'; list = list->next)
  95     {
  96       /* If it appears that we are handling options, then make sure that
  97          all of the options specified are actually valid.  Otherwise, the
  98          string should just be echoed. */
  99       temp++;
 100
 101       for (i = 0; temp[i]; i++)
 102         {
 103           if (strchr (VALID_ECHO_OPTIONS, temp[i]) == 0)
 104             break;
 105         }
 106
 107       /* echo - and echo -<nonopt> both mean to just echo the arguments. */
 108       if (*temp == 0 || temp[i])
 109         break;
 110
 111       /* All of the options in TEMP are valid options to ECHO.
 112          Handle them. */
 113       while (i = *temp++)
 114         {
 115           switch (i)
 116             {
 117             case 'n':
 118               display_return = 0;
 119               break;
 120 #if defined (V9_ECHO)
 121             case 'e':
 122               do_v9 = 1;
 123               break;
 124             case 'E':
 125               do_v9 = 0;
 126               break;
 127 #endif /* V9_ECHO */
 128             default:
 129               goto just_echo;   /* XXX */
 130             }
 131         }
 132     }
 133
 134 just_echo:
 135
 136   clearerr (stdout);    /* clear error before writing and testing success */
 137
 138   while (list)
 139     {
 140       i = len = 0;
 141       temp = do_v9 ? ansicstr (list->word->word, STRLEN (list->word->word), 1, &i, &len)
 142                    : list->word->word;
 143       if (temp)
 144         {
 145           if (do_v9)
 146             {
 147               for (s = temp; len > 0; len--)
 148                 putchar (*s++);
 149             }
 150           else
 151             printf ("%s", temp);
 152 #if defined (SunOS5)
 153           fflush (stdout);      /* Fix for bug in SunOS 5.5 printf(3) */
 154 #endif
 155         }
 156       if (do_v9 && temp)
 157         free (temp);
 158       list = list->next;
 159       if (i)
 160         {
 161           display_return = 0;
 162           break;
 163         }
 164       if (list)
 165         putchar(' ');
 166     }
 167
 168   if (display_return)
 169     putchar ('\n');
 170   fflush (stdout);
 171   if (ferror (stdout))
 172     {
 173       clearerr (stdout);
 174       return (EXECUTION_FAILURE);
 175     }
 176   return (EXECUTION_SUCCESS);
 177 }