1 /* echo.c - echo supporting -n and -e.
2 *
3 * Copyright 2007 Rob Landley <rob@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, "^?Een[-eE]", TOYFLAG_BIN|TOYFLAG_MAYFORK))
13
14 config ECHO
15 bool "echo"
16 default y
17 help
18 usage: echo [-neE] [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 Print escape sequences literally (default)
25 -e Process the following escape sequences:
26 \\ Backslash
27 \0NNN Octal values (1 to 3 digits)
28 \a Alert (beep/flash)
29 \b Backspace
30 \c Stop output here (avoids trailing newline)
31 \f Form feed
32 \n Newline
33 \r Carriage return
34 \t Horizontal tab
35 \v Vertical tab
36 \xHH Hexadecimal values (1 to 2 digits)
37 */
38
39 #define FOR_echo
40 #include "toys.h"
41
echo_main(void)42 void echo_main(void)
43 {
44 int i = 0, out;
45 char *arg, *c;
46
47 for (;;) {
48 arg = toys.optargs[i];
49 if (!arg) break;
50 if (i++) putchar(' ');
51
52 // Should we output arg verbatim?
53
54 if (!FLAG(e)) {
55 xprintf("%s", arg);
56 continue;
57 }
58
59 // Handle -e
60
61 for (c = arg;;) {
62 if (!(out = *(c++))) break;
63
64 // handle \escapes
65 if (out == '\\' && *c) {
66 int slash = *(c++), n = unescape(slash);
67
68 if (n) out = n;
69 else if (slash=='c') return;
70 else if (slash=='0') {
71 out = 0;
72 while (*c>='0' && *c<='7' && n++<3) out = (out*8)+*(c++)-'0';
73 } else if (slash=='x') {
74 out = 0;
75 while (n++<2) {
76 if (*c>='0' && *c<='9') out = (out*16)+*(c++)-'0';
77 else {
78 int temp = tolower(*c);
79 if (temp>='a' && temp<='f') {
80 out = (out*16)+temp-'a'+10;
81 c++;
82 } else {
83 if (n==1) {
84 --c;
85 out = '\\';
86 }
87 break;
88 }
89 }
90 }
91 // Slash in front of unknown character, print literal.
92 } else c--;
93 }
94 putchar(out);
95 }
96 }
97
98 // Output "\n" if no -n
99 if (!FLAG(n)) putchar('\n');
100 }
101