1 /* echo.c - echo supporting -n and -e. 2 * 3 * Copyright 2007 Rob Landley <rob (at) landley.net> 4 * 5 * See http://opengroup.org/onlinepubs/9699919799/utilities/echo.html 6 * 7 * Deviations from posix: we parse command line options, as Linux has 8 * consistently done since 1992. Posix defaults -e to on, we require -e. 9 * We also honor -- to _stop_ option parsing (bash doesn't, we go with 10 * consistency over compatibility here). 11 12 USE_ECHO(NEWTOY(echo, "^?en", TOYFLAG_BIN)) 13 14 config ECHO 15 bool "echo" 16 default y 17 help 18 usage: echo [-ne] [args...] 19 20 Write each argument to stdout, with one space between each, followed 21 by a newline. 22 23 -n No trailing newline 24 -e Process the following escape sequences: 25 \\ backslash 26 \0NNN octal values (1 to 3 digits) 27 \a alert (beep/flash) 28 \b backspace 29 \c stop output here (avoids trailing newline) 30 \f form feed 31 \n newline 32 \r carriage return 33 \t horizontal tab 34 \v vertical tab 35 \xHH hexadecimal values (1 to 2 digits) 36 */ 37 38 #define FOR_echo 39 #include "toys.h" 40 41 void echo_main(void) 42 { 43 int i = 0, out; 44 char *arg, *c; 45 46 for (;;) { 47 arg = toys.optargs[i]; 48 if (!arg) break; 49 if (i++) putchar(' '); 50 51 // Should we output arg verbatim? 52 53 if (!(toys.optflags & FLAG_e)) { 54 xprintf("%s", arg); 55 continue; 56 } 57 58 // Handle -e 59 60 for (c = arg;;) { 61 if (!(out = *(c++))) break; 62 63 // handle \escapes 64 if (out == '\\' && *c) { 65 int slash = *(c++), n = unescape(slash); 66 67 if (n) out = n; 68 else if (slash=='c') goto done; 69 else if (slash=='0') { 70 out = 0; 71 while (*c>='0' && *c<='7' && n++<3) out = (out*8)+*(c++)-'0'; 72 } else if (slash=='x') { 73 out = 0; 74 while (n++<2) { 75 if (*c>='0' && *c<='9') out = (out*16)+*(c++)-'0'; 76 else { 77 int temp = tolower(*c); 78 if (temp>='a' && temp<='f') { 79 out = (out*16)+temp-'a'+10; 80 c++; 81 } else break; 82 } 83 } 84 // Slash in front of unknown character, print literal. 85 } else c--; 86 } 87 putchar(out); 88 } 89 } 90 91 // Output "\n" if no -n 92 if (!(toys.optflags&FLAG_n)) putchar('\n'); 93 done: 94 xflush(); 95 } 96
