1/***********************************************************************
2*                                                                      *
3*               This software is part of the ast package               *
4*          Copyright (c) 1992-2011 AT&T Intellectual Property          *
5*                      and is licensed under the                       *
6*                  Common Public License, Version 1.0                  *
7*                    by AT&T Intellectual Property                     *
8*                                                                      *
9*                A copy of the License is available at                 *
10*            http://www.opensource.org/licenses/cpl1.0.txt             *
11*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
12*                                                                      *
13*              Information and Software Systems Research               *
14*                            AT&T Research                             *
15*                           Florham Park NJ                            *
16*                                                                      *
17*                 Glenn Fowler <gsf@research.att.com>                  *
18*                  David Korn <dgk@research.att.com>                   *
19*                                                                      *
20***********************************************************************/
21#pragma prototyped
22/*
23 * David Korn
24 * AT&T Bell Laboratories
25 *
26 * output the beginning portion of one or more files
27 */
28
29static const char usage[] =
30"[-n?\n@(#)$Id: head (AT&T Research) 2006-09-27 $\n]"
31USAGE_LICENSE
32"[+NAME?head - output beginning portion of one or more files ]"
33"[+DESCRIPTION?\bhead\b copies one or more input files to standard "
34    "output stopping at a designated point for each file or to the end of "
35    "the file whichever comes first. Copying ends at the point indicated by "
36    "the options. By default a header of the form \b==> \b\afilename\a\b "
37    "<==\b is output before all but the first file but this can be changed "
38    "with the \b-q\b and \b-v\b options.]"
39"[+?If no \afile\a is given, or if the \afile\a is \b-\b, \bhead\b "
40    "copies from standard input starting at the current location.]"
41"[+?The option argument for \b-c\b, and \b-s\b can optionally be "
42    "followed by one of the following characters to specify a different unit "
43    "other than a single byte:]"
44    "{"
45        "[+b?512 bytes.]"
46        "[+k?1-killobyte.]"
47        "[+m?1-megabyte.]"
48    "}"
49"[+?For backwards compatibility, \b-\b\anumber\a is equivalent to \b-n\b "
50    "\anumber\a.]"
51"[n:lines?Copy \alines\a lines from each file.]#[lines:=10]"
52"[c:bytes?Copy \achars\a bytes from each file.]#[chars]"
53"[q:quiet|silent?Never ouput filename headers.]"
54"[s:skip?Skip \askip\a characters or lines from each file before "
55    "copying.]#[skip]"
56"[v:verbose?Always ouput filename headers.]"
57    "\n\n"
58"[ file ... ]"
59    "\n\n"
60"[+EXIT STATUS?]"
61    "{"
62        "[+0?All files copied successfully.]"
63        "[+>0?One or more files did not copy.]"
64    "}"
65"[+SEE ALSO?\bcat\b(1), \btail\b(1)]"
66;
67
68#include <cmd.h>
69
70int
71b_head(int argc, register char** argv, void* context)
72{
73	static const char	header_fmt[] = "\n==> %s <==\n";
74
75	register Sfio_t*	fp;
76	register char*		cp;
77	register off_t		keep = 10;
78	register off_t		skip = 0;
79	register int		delim = '\n';
80	int			header = 1;
81	char*			format = (char*)header_fmt+1;
82
83	cmdinit(argc, argv, context, ERROR_CATALOG, 0);
84	for (;;)
85	{
86		switch (optget(argv, usage))
87		{
88		case 'c':
89			delim = -1;
90			/*FALLTHROUGH*/
91		case 'n':
92			if (opt_info.offset && argv[opt_info.index][opt_info.offset] == 'c')
93			{
94				delim = -1;
95				opt_info.offset++;
96			}
97			if ((keep = opt_info.number) <=0)
98				error(2, "%s: %I*d: positive numeric option argument expected", opt_info.name, sizeof(keep), keep);
99			continue;
100		case 'q':
101			header = argc;
102			continue;
103		case 'v':
104			header = 0;
105			continue;
106		case 's':
107			skip = opt_info.number;
108			continue;
109		case '?':
110			error(ERROR_usage(2), "%s", opt_info.arg);
111			continue;
112		case ':':
113			error(2, "%s", opt_info.arg);
114			continue;
115		}
116		break;
117	}
118	argv += opt_info.index;
119	argc -= opt_info.index;
120	if (error_info.errors)
121		error(ERROR_usage(2), "%s", optusage(NiL));
122	if (cp = *argv)
123		argv++;
124	do
125	{
126		if (!cp || streq(cp, "-"))
127		{
128			cp = "/dev/stdin";
129			fp = sfstdin;
130			sfset(fp, SF_SHARE, 1);
131		}
132		else if (!(fp = sfopen(NiL, cp, "r")))
133		{
134			error(ERROR_system(0), "%s: cannot open", cp);
135			continue;
136		}
137		if (argc > header)
138			sfprintf(sfstdout, format, cp);
139		format = (char*)header_fmt;
140		if (skip > 0)
141			sfmove(fp, NiL, skip, delim);
142		if (sfmove(fp, sfstdout, keep, delim) < 0 && errno != EPIPE)
143			error(ERROR_system(0), "%s: read error", cp);
144		if (fp != sfstdin)
145			sfclose(fp);
146	} while (cp = *argv++);
147	if (sfsync(sfstdout))
148		error(ERROR_system(0), "write error");
149	return error_info.errors != 0;
150}
151