echo.c revision dd7bc3319deb2b77c5d07a51b7d6cd7e11b5beb0 
1/*	$NetBSD: echo.c,v 1.12 2005/02/06 04:43:43 perry Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	@(#)echo.c	8.1 (Berkeley) 5/31/93
35 */
36
37/*
38 * Echo command.
39 *
40 * echo is steeped in tradition - several of them!
41 * netbsd has supported 'echo [-n | -e] args' in spite of -e not being
42 * documented anywhere.
43 * Posix requires that -n be supported, output from strings containing
44 * \ is implementation defined
45 * The Single Unix Spec requires that \ escapes be treated as if -e
46 * were set, but that -n not be treated as an option.
47 * (ksh supports 'echo [-eEn] args', but not -- so that it is actually
48 * impossible to actually output '-n')
49 *
50 * It is suggested that 'printf "%b" "string"' be used to get \ sequences
51 * expanded.  printf is now a builtin of netbsd's sh and csh.
52 */
53
54//#define main echocmd
55
56#include "bltin.h"
57
58int
59echocmd(int argc, char **argv)
60{
61	char **ap;
62	char *p;
63	char c;
64	int count;
65	int nflag = 0;
66	int eflag = 0;
67
68	ap = argv;
69	if (argc)
70		ap++;
71
72	if ((p = *ap) != NULL) {
73		if (equal(p, "-n")) {
74			nflag = 1;
75			ap++;
76		} else if (equal(p, "-e")) {
77			eflag = 1;
78			ap++;
79		}
80	}
81
82	while ((p = *ap++) != NULL) {
83		while ((c = *p++) != '\0') {
84			if (c == '\\' && eflag) {
85				switch (*p++) {
86				case 'a':  c = '\a';  break;	/* bell */
87				case 'b':  c = '\b';  break;
88				case 'c':  return 0;		/* exit */
89				case 'e':  c =  033;  break;	/* escape */
90				case 'f':  c = '\f';  break;
91				case 'n':  c = '\n';  break;
92				case 'r':  c = '\r';  break;
93				case 't':  c = '\t';  break;
94				case 'v':  c = '\v';  break;
95				case '\\':  break;		/* c = '\\' */
96				case '0':
97					c = 0;
98					count = 3;
99					while (--count >= 0 && (unsigned)(*p - '0') < 8)
100						c = (c << 3) + (*p++ - '0');
101					break;
102				default:
103					/* Output the '/' and char following */
104					p--;
105					break;
106				}
107			}
108			putchar(c);
109		}
110		if (*ap)
111			putchar(' ');
112	}
113	if (! nflag)
114		putchar('\n');
115	return 0;
116}
117