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 on the standard output followed by a newline.
  42
  43 Options:
  44   -n    do not append a newline
  45   -e    enable interpretation of the following backslash escapes
  46   -E    explicitly suppress interpretation of backslash escapes
  47
  48 `echo' interprets the following backslash-escaped characters:
  49   \a    alert (bell)
  50   \b    backspace
  51   \c    suppress further output
  52   \e    escape character
  53   \f    form feed
  54   \n    new line
  55   \r    carriage return
  56   \t    horizontal tab
  57   \v    vertical tab
  58   \\    backslash
  59   \0nnn the character whose ASCII code is NNN (octal).  NNN can be
  60         0 to 3 octal digits
  61   \xHH  the eight-bit character whose value is HH (hexadecimal).  HH
  62         can be one or two hex digits
  63
  64 Exit Status:
  65 Returns success unless a write error occurs.
  66 $END
  67
  68 $BUILTIN echo
  69 $FUNCTION echo_builtin
  70 $DEPENDS_ON !V9_ECHO
  71 $SHORT_DOC echo [-n] [arg ...]
  72 Write arguments to the standard output.
  73
  74 Display the ARGs on the standard output followed by a newline.
  75
  76 Options:
  77   -n    do not append a newline
  78
  79 Exit Status:
  80 Returns success unless a write error occurs.
  81 $END
  82
  83 #if defined (V9_ECHO)
  84 #  define VALID_ECHO_OPTIONS "neE"
  85 #else /* !V9_ECHO */
  86 #  define VALID_ECHO_OPTIONS "n"
  87 #endif /* !V9_ECHO */
  88
  89 /* System V machines already have a /bin/sh with a v9 behaviour.  We
  90    give Bash the identical behaviour for these machines so that the
  91    existing system shells won't barf.  Regrettably, the SUS v2 has
  92    standardized the Sys V echo behavior.  This variable is external
  93    so that we can have a `shopt' variable to control it at runtime. */
  94 #if defined (DEFAULT_ECHO_TO_XPG) || defined (STRICT_POSIX)
  95 int xpg_echo = 1;
  96 #else
  97 int xpg_echo = 0;
  98 #endif /* DEFAULT_ECHO_TO_XPG */
  99
 100 extern int posixly_correct;
 101
 102 /* Print the words in LIST to standard output.  If the first word is
 103    `-n', then don't print a trailing newline.  We also support the
 104    echo syntax from Version 9 Unix systems. */
 105 int
 106 echo_builtin (list)
 107      WORD_LIST *list;
 108 {
 109   int display_return, do_v9, i, len;
 110   char *temp, *s;
 111
 112   do_v9 = xpg_echo;
 113   display_return = 1;
 114
 115   if (posixly_correct && xpg_echo)
 116     goto just_echo;
 117
 118   for (; list && (temp = list->word->word) && *temp == '-'; list = list->next)
 119     {
 120       /* If it appears that we are handling options, then make sure that
 121          all of the options specified are actually valid.  Otherwise, the
 122          string should just be echoed. */
 123       temp++;
 124
 125       for (i = 0; temp[i]; i++)
 126         {
 127           if (strchr (VALID_ECHO_OPTIONS, temp[i]) == 0)
 128             break;
 129         }
 130
 131       /* echo - and echo -<nonopt> both mean to just echo the arguments. */
 132       if (*temp == 0 || temp[i])
 133         break;
 134
 135       /* All of the options in TEMP are valid options to ECHO.
 136          Handle them. */
 137       while (i = *temp++)
 138         {
 139           switch (i)
 140             {
 141             case 'n':
 142               display_return = 0;
 143               break;
 144 #if defined (V9_ECHO)
 145             case 'e':
 146               do_v9 = 1;
 147               break;
 148             case 'E':
 149               do_v9 = 0;
 150               break;
 151 #endif /* V9_ECHO */
 152             default:
 153               goto just_echo;   /* XXX */
 154             }
 155         }
 156     }
 157
 158 just_echo:
 159
 160   clearerr (stdout);    /* clear error before writing and testing success */
 161
 162   terminate_immediately++;
 163   while (list)
 164     {
 165       i = len = 0;
 166       temp = do_v9 ? ansicstr (list->word->word, STRLEN (list->word->word), 1, &i, &len)
 167                    : list->word->word;
 168       if (temp)
 169         {
 170           if (do_v9)
 171             {
 172               for (s = temp; len > 0; len--)
 173                 putchar (*s++);
 174             }
 175           else
 176             printf ("%s", temp);
 177 #if defined (SunOS5)
 178           fflush (stdout);      /* Fix for bug in SunOS 5.5 printf(3) */
 179 #endif
 180         }
 181       if (do_v9 && temp)
 182         free (temp);
 183       list = list->next;
 184       if (i)
 185         {
 186           display_return = 0;
 187           break;
 188         }
 189       if (list)
 190         putchar(' ');
 191     }
 192
 193   if (display_return)
 194     putchar ('\n');
 195
 196   terminate_immediately--;
 197   return (sh_chkwrite (EXECUTION_SUCCESS));
 198 }