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) 1987-2018 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   \uHHHH        the Unicode character whose value is the hexadecimal value HHHH.
  66                 HHHH can be one to four hex digits.
  67   \UHHHHHHHH the Unicode character whose value is the hexadecimal value
  68                 HHHHHHHH. HHHHHHHH can be one to eight hex digits.
  69
  70 Exit Status:
  71 Returns success unless a write error occurs.
  72 $END
  73
  74 $BUILTIN echo
  75 $FUNCTION echo_builtin
  76 $DEPENDS_ON !V9_ECHO
  77 $SHORT_DOC echo [-n] [arg ...]
  78 Write arguments to the standard output.
  79
  80 Display the ARGs on the standard output followed by a newline.
  81
  82 Options:
  83   -n    do not append a newline
  84
  85 Exit Status:
  86 Returns success unless a write error occurs.
  87 $END
  88
  89 #if defined (V9_ECHO)
  90 #  define VALID_ECHO_OPTIONS "neE"
  91 #else /* !V9_ECHO */
  92 #  define VALID_ECHO_OPTIONS "n"
  93 #endif /* !V9_ECHO */
  94
  95 /* System V machines already have a /bin/sh with a v9 behaviour.  We
  96    give Bash the identical behaviour for these machines so that the
  97    existing system shells won't barf.  Regrettably, the SUS v2 has
  98    standardized the Sys V echo behavior.  This variable is external
  99    so that we can have a `shopt' variable to control it at runtime. */
 100 #if defined (DEFAULT_ECHO_TO_XPG) || defined (STRICT_POSIX)
 101 int xpg_echo = 1;
 102 #else
 103 int xpg_echo = 0;
 104 #endif /* DEFAULT_ECHO_TO_XPG */
 105
 106 /* Print the words in LIST to standard output.  If the first word is
 107    `-n', then don't print a trailing newline.  We also support the
 108    echo syntax from Version 9 Unix systems. */
 109 int
 110 echo_builtin (list)
 111      WORD_LIST *list;
 112 {
 113   int display_return, do_v9, i, len;
 114   char *temp, *s;
 115
 116   do_v9 = xpg_echo;
 117   display_return = 1;
 118
 119   if (posixly_correct && xpg_echo)
 120     goto just_echo;
 121
 122   for (; list && (temp = list->word->word) && *temp == '-'; list = list->next)
 123     {
 124       /* If it appears that we are handling options, then make sure that
 125          all of the options specified are actually valid.  Otherwise, the
 126          string should just be echoed. */
 127       temp++;
 128
 129       for (i = 0; temp[i]; i++)
 130         {
 131           if (strchr (VALID_ECHO_OPTIONS, temp[i]) == 0)
 132             break;
 133         }
 134
 135       /* echo - and echo -<nonopt> both mean to just echo the arguments. */
 136       if (*temp == 0 || temp[i])
 137         break;
 138
 139       /* All of the options in TEMP are valid options to ECHO.
 140          Handle them. */
 141       while (i = *temp++)
 142         {
 143           switch (i)
 144             {
 145             case 'n':
 146               display_return = 0;
 147               break;
 148 #if defined (V9_ECHO)
 149             case 'e':
 150               do_v9 = 1;
 151               break;
 152             case 'E':
 153               do_v9 = 0;
 154               break;
 155 #endif /* V9_ECHO */
 156             default:
 157               goto just_echo;   /* XXX */
 158             }
 159         }
 160     }
 161
 162 just_echo:
 163
 164   clearerr (stdout);    /* clear error before writing and testing success */
 165
 166   while (list)
 167     {
 168       i = len = 0;
 169       temp = do_v9 ? ansicstr (list->word->word, STRLEN (list->word->word), 1, &i, &len)
 170                    : list->word->word;
 171       if (temp)
 172         {
 173           if (do_v9)
 174             {
 175               for (s = temp; len > 0; len--)
 176                 putchar (*s++);
 177             }
 178           else
 179             printf ("%s", temp);
 180 #if defined (SunOS5)
 181           fflush (stdout);      /* Fix for bug in SunOS 5.5 printf(3) */
 182 #endif
 183         }
 184       QUIT;
 185       if (do_v9 && temp)
 186         free (temp);
 187       list = list->next;
 188       if (i)
 189         {
 190           display_return = 0;
 191           break;
 192         }
 193       if (list)
 194         putchar(' ');
 195       QUIT;
 196     }
 197
 198   if (display_return)
 199     putchar ('\n');
 200
 201   return (sh_chkwrite (EXECUTION_SUCCESS));
 202 }