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) 1987-2009 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
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation, either version 3 of the License, or
  11 (at your option) any later version.
  12
  13 Bash is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 $PRODUCES echo.c
  22 #include <config.h>
  23
  24 #if defined (HAVE_UNISTD_H)
  25 #  include <unistd.h>
  26 #endif
  27
  28 #include "../bashansi.h"
  29
  30 #include <stdio.h>
  31 #include "../shell.h"
  32
  33 #include "common.h"
  34
  35 $BUILTIN echo
  36 $FUNCTION echo_builtin
  37 $DEPENDS_ON V9_ECHO
  38 $SHORT_DOC echo [-neE] [arg ...]
  39 Write arguments to the standard output.
  40
  41 Display the ARGs, separated by a single space character and followed by a
  42 newline, on the standard output.
  43
  44 Options:
  45   -n    do not append a newline
  46   -e    enable interpretation of the following backslash escapes
  47   -E    explicitly suppress interpretation of backslash escapes
  48
  49 `echo' interprets the following backslash-escaped characters:
  50   \a    alert (bell)
  51   \b    backspace
  52   \c    suppress further output
  53   \e    escape character
  54   \E    escape character
  55   \f    form feed
  56   \n    new line
  57   \r    carriage return
  58   \t    horizontal tab
  59   \v    vertical tab
  60   \\    backslash
  61   \0nnn the character whose ASCII code is NNN (octal).  NNN can be
  62         0 to 3 octal digits
  63   \xHH  the eight-bit character whose value is HH (hexadecimal).  HH
  64         can be one or two hex digits
  65
  66 Exit Status:
  67 Returns success unless a write error occurs.
  68 $END
  69
  70 $BUILTIN echo
  71 $FUNCTION echo_builtin
  72 $DEPENDS_ON !V9_ECHO
  73 $SHORT_DOC echo [-n] [arg ...]
  74 Write arguments to the standard output.
  75
  76 Display the ARGs on the standard output followed by a newline.
  77
  78 Options:
  79   -n    do not append a newline
  80
  81 Exit Status:
  82 Returns success unless a write error occurs.
  83 $END
  84
  85 #if defined (V9_ECHO)
  86 #  define VALID_ECHO_OPTIONS "neE"
  87 #else /* !V9_ECHO */
  88 #  define VALID_ECHO_OPTIONS "n"
  89 #endif /* !V9_ECHO */
  90
  91 /* System V machines already have a /bin/sh with a v9 behaviour.  We
  92    give Bash the identical behaviour for these machines so that the
  93    existing system shells won't barf.  Regrettably, the SUS v2 has
  94    standardized the Sys V echo behavior.  This variable is external
  95    so that we can have a `shopt' variable to control it at runtime. */
  96 #if defined (DEFAULT_ECHO_TO_XPG) || defined (STRICT_POSIX)
  97 int xpg_echo = 1;
  98 #else
  99 int xpg_echo = 0;
 100 #endif /* DEFAULT_ECHO_TO_XPG */
 101
 102 extern int posixly_correct;
 103
 104 /* Print the words in LIST to standard output.  If the first word is
 105    `-n', then don't print a trailing newline.  We also support the
 106    echo syntax from Version 9 Unix systems. */
 107 int
 108 echo_builtin (list)
 109      WORD_LIST *list;
 110 {
 111   int display_return, do_v9, i, len;
 112   char *temp, *s;
 113
 114   do_v9 = xpg_echo;
 115   display_return = 1;
 116
 117   if (posixly_correct && xpg_echo)
 118     goto just_echo;
 119
 120   for (; list && (temp = list->word->word) && *temp == '-'; list = list->next)
 121     {
 122       /* If it appears that we are handling options, then make sure that
 123          all of the options specified are actually valid.  Otherwise, the
 124          string should just be echoed. */
 125       temp++;
 126
 127       for (i = 0; temp[i]; i++)
 128         {
 129           if (strchr (VALID_ECHO_OPTIONS, temp[i]) == 0)
 130             break;
 131         }
 132
 133       /* echo - and echo -<nonopt> both mean to just echo the arguments. */
 134       if (*temp == 0 || temp[i])
 135         break;
 136
 137       /* All of the options in TEMP are valid options to ECHO.
 138          Handle them. */
 139       while (i = *temp++)
 140         {
 141           switch (i)
 142             {
 143             case 'n':
 144               display_return = 0;
 145               break;
 146 #if defined (V9_ECHO)
 147             case 'e':
 148               do_v9 = 1;
 149               break;
 150             case 'E':
 151               do_v9 = 0;
 152               break;
 153 #endif /* V9_ECHO */
 154             default:
 155               goto just_echo;   /* XXX */
 156             }
 157         }
 158     }
 159
 160 just_echo:
 161
 162   clearerr (stdout);    /* clear error before writing and testing success */
 163
 164   terminate_immediately++;
 165   while (list)
 166     {
 167       i = len = 0;
 168       temp = do_v9 ? ansicstr (list->word->word, STRLEN (list->word->word), 1, &i, &len)
 169                    : list->word->word;
 170       if (temp)
 171         {
 172           if (do_v9)
 173             {
 174               for (s = temp; len > 0; len--)
 175                 putchar (*s++);
 176             }
 177           else
 178             printf ("%s", temp);
 179 #if defined (SunOS5)
 180           fflush (stdout);      /* Fix for bug in SunOS 5.5 printf(3) */
 181 #endif
 182         }
 183       if (do_v9 && temp)
 184         free (temp);
 185       list = list->next;
 186       if (i)
 187         {
 188           display_return = 0;
 189           break;
 190         }
 191       if (list)
 192         putchar(' ');
 193     }
 194
 195   if (display_return)
 196     putchar ('\n');
 197
 198   terminate_immediately--;
 199   return (sh_chkwrite (EXECUTION_SUCCESS));
 200 }