src/echo.c

   1 /* echo.c, derived from code echo.c in Bash.
   2    Copyright (C) 87,89, 1991-1997, 1999 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 #include <config.h>
  19 #include <stdio.h>
  20 #include <sys/types.h>
  21 #include "system.h"
  22 #include "long-options.h"
  23
  24 /* The official name of this program (e.g., no `g' prefix).  */
  25 #define PROGRAM_NAME "echo"
  26
  27 #define AUTHORS "FIXME unknown"
  28
  29 /* echo [-neE] [arg ...]
  30 Output the ARGs.  If -n is specified, the trailing newline is
  31 suppressed.  If the -e option is given, interpretation of the
  32 following backslash-escaped characters is turned on:
  33         \a      alert (bell)
  34         \b      backspace
  35         \c      suppress trailing newline
  36         \f      form feed
  37         \n      new line
  38         \r      carriage return
  39         \t      horizontal tab
  40         \v      vertical tab
  41         \\      backslash
  42         \num    the character whose ASCII code is NUM (octal).
  43
  44 You can explicitly turn off the interpretation of the above characters
  45 on System V systems with the -E option.
  46 */
  47
  48 /* If defined, interpret backslash escapes if -e is given.  */
  49 #define V9_ECHO
  50
  51 /* If defined, interpret backslash escapes unless -E is given.
  52    V9_ECHO must also be defined.  */
  53 /* #define V9_DEFAULT */
  54
  55 #if defined (V9_ECHO)
  56 # if defined (V9_DEFAULT)
  57 #  define VALID_ECHO_OPTIONS "neE"
  58 # else
  59 #  define VALID_ECHO_OPTIONS "ne"
  60 # endif /* !V9_DEFAULT */
  61 #else /* !V9_ECHO */
  62 # define VALID_ECHO_OPTIONS "n"
  63 #endif /* !V9_ECHO */
  64
  65 /* The name this program was run with. */
  66 char *program_name;
  67
  68 void
  69 usage (int status)
  70 {
  71   if (status != 0)
  72     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  73              program_name);
  74   else
  75     {
  76       printf (_("Usage: %s [OPTION]... [STRING]...\n"), program_name);
  77       printf (_("\
  78 Echo the STRING(s) to standard output.\n\
  79 \n\
  80   -n              do not output the trailing newline\n\
  81   -e              enable interpretation of the backslash-escaped characters\n\
  82                     listed below\n\
  83   -E              disable interpretation of those sequences in STRINGs\n\
  84       --help      display this help and exit (should be alone)\n\
  85       --version   output version information and exit (should be alone)\n\
  86 \n\
  87 Without -E, the following sequences are recognized and interpolated:\n\
  88 \n\
  89   \\NNN   the character whose ASCII code is NNN (octal)\n\
  90   \\\\     backslash\n\
  91   \\a     alert (BEL)\n\
  92   \\b     backspace\n\
  93   \\c     suppress trailing newline\n\
  94   \\f     form feed\n\
  95   \\n     new line\n\
  96   \\r     carriage return\n\
  97   \\t     horizontal tab\n\
  98   \\v     vertical tab\n\
  99 "));
 100       puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
 101     }
 102   exit (status);
 103 }
 104
 105 /* Print the words in LIST to standard output.  If the first word is
 106    `-n', then don't print a trailing newline.  We also support the
 107    echo syntax from Version 9 unix systems. */
 108
 109 int
 110 main (int argc, char **argv)
 111 {
 112   int display_return = 1, do_v9 = 0;
 113   int allow_options = 1;
 114
 115   program_name = argv[0];
 116   setlocale (LC_ALL, "");
 117   bindtextdomain (PACKAGE, LOCALEDIR);
 118   textdomain (PACKAGE);
 119
 120   /* Don't recognize --help or --version if POSIXLY_CORRECT is set.  */
 121   if (getenv ("POSIXLY_CORRECT") == NULL)
 122     parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
 123                       AUTHORS, usage);
 124   else
 125     allow_options = 0;
 126
 127 /* System V machines already have a /bin/sh with a v9 behaviour.  We
 128    use the identical behaviour for these machines so that the
 129    existing system shell scripts won't barf. */
 130 #if defined (V9_ECHO) && defined (V9_DEFAULT)
 131   do_v9 = allow_options;
 132 #endif
 133
 134   --argc;
 135   ++argv;
 136
 137   while (argc > 0 && *argv[0] == '-')
 138     {
 139       register char *temp;
 140       register int i;
 141
 142       /* If it appears that we are handling options, then make sure that
 143          all of the options specified are actually valid.  Otherwise, the
 144          string should just be echoed. */
 145       temp = argv[0] + 1;
 146
 147       for (i = 0; temp[i]; i++)
 148         {
 149           if (strrchr (VALID_ECHO_OPTIONS, temp[i]) == 0)
 150             goto just_echo;
 151         }
 152
 153       if (!*temp)
 154         goto just_echo;
 155
 156       /* All of the options in TEMP are valid options to ECHO.
 157          Handle them. */
 158       while (*temp)
 159         {
 160           if (allow_options && *temp == 'n')
 161             display_return = 0;
 162 #if defined (V9_ECHO)
 163           else if (allow_options && *temp == 'e')
 164             do_v9 = 1;
 165 # if defined (V9_DEFAULT)
 166           else if (allow_options && *temp == 'E')
 167             do_v9 = 0;
 168 # endif /* V9_DEFAULT */
 169 #endif /* V9_ECHO */
 170           else
 171             goto just_echo;
 172
 173           temp++;
 174         }
 175       argc--;
 176       argv++;
 177     }
 178
 179 just_echo:
 180
 181   if (argc > 0)
 182     {
 183 #if defined (V9_ECHO)
 184       if (do_v9)
 185         {
 186           while (argc > 0)
 187             {
 188               register char *s = argv[0];
 189               register int c;
 190
 191               while ((c = *s++))
 192                 {
 193                   if (c == '\\' && *s)
 194                     {
 195                       switch (c = *s++)
 196                         {
 197                         case 'a': c = '\007'; break;
 198                         case 'b': c = '\b'; break;
 199                         case 'c': display_return = 0; continue;
 200                         case 'f': c = '\f'; break;
 201                         case 'n': c = '\n'; break;
 202                         case 'r': c = '\r'; break;
 203                         case 't': c = '\t'; break;
 204                         case 'v': c = (int) 0x0B; break;
 205                         case '0': case '1': case '2': case '3':
 206                         case '4': case '5': case '6': case '7':
 207                           c -= '0';
 208                           if (*s >= '0' && *s <= '7')
 209                             c = c * 8 + (*s++ - '0');
 210                           if (*s >= '0' && *s <= '7')
 211                             c = c * 8 + (*s++ - '0');
 212                           break;
 213                         case '\\': break;
 214                         default:  putchar ('\\'); break;
 215                         }
 216                     }
 217                   putchar(c);
 218                 }
 219               argc--;
 220               argv++;
 221               if (argc > 0)
 222                 putchar(' ');
 223             }
 224         }
 225       else
 226 #endif /* V9_ECHO */
 227         {
 228           while (argc > 0)
 229             {
 230               fputs (argv[0], stdout);
 231               argc--;
 232               argv++;
 233               if (argc > 0)
 234                 putchar (' ');
 235             }
 236         }
 237     }
 238   if (display_return)
 239     putchar ('\n');
 240   exit (0);
 241 }