src/echo.c

   1 /* echo.c, derived from code echo.c in Bash.
   2    Copyright (C) 87,89, 1991-1997, 1999, 2000 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 "closeout.h"
  23 #include "long-options.h"
  24
  25 /* The official name of this program (e.g., no `g' prefix).  */
  26 #define PROGRAM_NAME "echo"
  27
  28 #define AUTHORS "FIXME unknown"
  29
  30 /* echo [-neE] [arg ...]
  31 Output the ARGs.  If -n is specified, the trailing newline is
  32 suppressed.  If the -e option is given, interpretation of the
  33 following backslash-escaped characters is turned on:
  34         \a      alert (bell)
  35         \b      backspace
  36         \c      suppress trailing newline
  37         \f      form feed
  38         \n      new line
  39         \r      carriage return
  40         \t      horizontal tab
  41         \v      vertical tab
  42         \\      backslash
  43         \num    the character whose ASCII code is NUM (octal).
  44
  45 You can explicitly turn off the interpretation of the above characters
  46 on System V systems with the -E option.
  47 */
  48
  49 /* If defined, interpret backslash escapes if -e is given.  */
  50 #define V9_ECHO
  51
  52 /* If defined, interpret backslash escapes unless -E is given.
  53    V9_ECHO must also be defined.  */
  54 /* #define V9_DEFAULT */
  55
  56 #if defined (V9_ECHO)
  57 # if defined (V9_DEFAULT)
  58 #  define VALID_ECHO_OPTIONS "neE"
  59 # else
  60 #  define VALID_ECHO_OPTIONS "ne"
  61 # endif /* !V9_DEFAULT */
  62 #else /* !V9_ECHO */
  63 # define VALID_ECHO_OPTIONS "n"
  64 #endif /* !V9_ECHO */
  65
  66 /* The name this program was run with. */
  67 char *program_name;
  68
  69 void
  70 usage (int status)
  71 {
  72   if (status != 0)
  73     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  74              program_name);
  75   else
  76     {
  77       printf (_("Usage: %s [OPTION]... [STRING]...\n"), program_name);
  78       printf (_("\
  79 Echo the STRING(s) to standard output.\n\
  80 \n\
  81   -n              do not output the trailing newline\n\
  82   -e              enable interpretation of the backslash-escaped characters\n\
  83                     listed below\n\
  84   -E              disable interpretation of those sequences in STRINGs\n\
  85       --help      display this help and exit (should be alone)\n\
  86       --version   output version information and exit (should be alone)\n\
  87 \n\
  88 Without -E, the following sequences are recognized and interpolated:\n\
  89 \n\
  90   \\NNN   the character whose ASCII code is NNN (octal)\n\
  91   \\\\     backslash\n\
  92   \\a     alert (BEL)\n\
  93   \\b     backspace\n\
  94   \\c     suppress trailing newline\n\
  95   \\f     form feed\n\
  96   \\n     new line\n\
  97   \\r     carriage return\n\
  98   \\t     horizontal tab\n\
  99   \\v     vertical tab\n\
 100 "));
 101       puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
 102     }
 103   exit (status);
 104 }
 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
 110 int
 111 main (int argc, char **argv)
 112 {
 113   int display_return = 1, do_v9 = 0;
 114   int allow_options = 1;
 115
 116   program_name = argv[0];
 117   setlocale (LC_ALL, "");
 118   bindtextdomain (PACKAGE, LOCALEDIR);
 119   textdomain (PACKAGE);
 120
 121   atexit (close_stdout);
 122
 123   /* Don't recognize --help or --version if POSIXLY_CORRECT is set.  */
 124   if (getenv ("POSIXLY_CORRECT") == NULL)
 125     parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
 126                       AUTHORS, usage);
 127   else
 128     allow_options = 0;
 129
 130 /* System V machines already have a /bin/sh with a v9 behaviour.  We
 131    use the identical behaviour for these machines so that the
 132    existing system shell scripts won't barf. */
 133 #if defined (V9_ECHO) && defined (V9_DEFAULT)
 134   do_v9 = allow_options;
 135 #endif
 136
 137   --argc;
 138   ++argv;
 139
 140   while (argc > 0 && *argv[0] == '-')
 141     {
 142       register char *temp;
 143       register int i;
 144
 145       /* If it appears that we are handling options, then make sure that
 146          all of the options specified are actually valid.  Otherwise, the
 147          string should just be echoed. */
 148       temp = argv[0] + 1;
 149
 150       for (i = 0; temp[i]; i++)
 151         {
 152           if (strrchr (VALID_ECHO_OPTIONS, temp[i]) == 0)
 153             goto just_echo;
 154         }
 155
 156       if (!*temp)
 157         goto just_echo;
 158
 159       /* All of the options in TEMP are valid options to ECHO.
 160          Handle them. */
 161       while (*temp)
 162         {
 163           if (allow_options && *temp == 'n')
 164             display_return = 0;
 165 #if defined (V9_ECHO)
 166           else if (allow_options && *temp == 'e')
 167             do_v9 = 1;
 168 # if defined (V9_DEFAULT)
 169           else if (allow_options && *temp == 'E')
 170             do_v9 = 0;
 171 # endif /* V9_DEFAULT */
 172 #endif /* V9_ECHO */
 173           else
 174             goto just_echo;
 175
 176           temp++;
 177         }
 178       argc--;
 179       argv++;
 180     }
 181
 182 just_echo:
 183
 184   if (argc > 0)
 185     {
 186 #if defined (V9_ECHO)
 187       if (do_v9)
 188         {
 189           while (argc > 0)
 190             {
 191               register char *s = argv[0];
 192               register int c;
 193
 194               while ((c = *s++))
 195                 {
 196                   if (c == '\\' && *s)
 197                     {
 198                       switch (c = *s++)
 199                         {
 200                         case 'a': c = '\007'; break;
 201                         case 'b': c = '\b'; break;
 202                         case 'c': display_return = 0; continue;
 203                         case 'f': c = '\f'; break;
 204                         case 'n': c = '\n'; break;
 205                         case 'r': c = '\r'; break;
 206                         case 't': c = '\t'; break;
 207                         case 'v': c = (int) 0x0B; break;
 208                         case '0': case '1': case '2': case '3':
 209                         case '4': case '5': case '6': case '7':
 210                           c -= '0';
 211                           if (*s >= '0' && *s <= '7')
 212                             c = c * 8 + (*s++ - '0');
 213                           if (*s >= '0' && *s <= '7')
 214                             c = c * 8 + (*s++ - '0');
 215                           break;
 216                         case '\\': break;
 217                         default:  putchar ('\\'); break;
 218                         }
 219                     }
 220                   putchar(c);
 221                 }
 222               argc--;
 223               argv++;
 224               if (argc > 0)
 225                 putchar(' ');
 226             }
 227         }
 228       else
 229 #endif /* V9_ECHO */
 230         {
 231           while (argc > 0)
 232             {
 233               fputs (argv[0], stdout);
 234               argc--;
 235               argv++;
 236               if (argc > 0)
 237                 putchar (' ');
 238             }
 239         }
 240     }
 241   if (display_return)
 242     putchar ('\n');
 243   exit (0);
 244 }