1 /* vi: set sw=4 ts=4: */
3 * head implementation for busybox
5 * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 /* BB_AUDIT SUSv3 compliant */
11 /* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
12 /* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
14 //usage:#define head_trivial_usage
15 //usage: "[OPTIONS] [FILE]..."
16 //usage:#define head_full_usage "\n\n"
17 //usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
18 //usage: "With more than one FILE, precede each with a filename header.\n"
19 //usage: "\n -n N[kbm] Print first N lines"
20 //usage: IF_FEATURE_FANCY_HEAD(
21 //usage: "\n -c N[kbm] Print first N bytes"
22 //usage: "\n -q Never print headers"
23 //usage: "\n -v Always print headers"
26 //usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
28 //usage:#define head_example_usage
29 //usage: "$ head -n 2 /etc/passwd\n"
30 //usage: "root:x:0:0:root:/root:/bin/bash\n"
31 //usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
35 /* This is a NOEXEC applet. Be very careful! */
37 static const char head_opts[] ALIGN1 =
39 #if ENABLE_FEATURE_FANCY_HEAD
44 static const struct suffix_mult head_suffixes[] = {
51 #define header_fmt_str "\n==> %s <==\n"
53 int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
54 int head_main(int argc, char **argv)
56 unsigned long count = 10;
58 #if ENABLE_FEATURE_FANCY_HEAD
60 int header_threshhold = 1;
67 int retval = EXIT_SUCCESS;
69 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
70 /* Allow legacy syntax of an initial numeric option without -n. */
71 if (argv[1] && argv[1][0] == '-'
72 && isdigit(argv[1][1])
81 /* No size benefit in converting this to getopt32 */
82 while ((opt = getopt(argc, argv, head_opts)) > 0) {
84 #if ENABLE_FEATURE_FANCY_HEAD
86 header_threshhold = INT_MAX;
89 header_threshhold = -1;
97 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
100 count = xatoul_sfx(p, head_suffixes);
110 *--argv = (char*)"-";
112 fmt = header_fmt_str + 1;
113 #if ENABLE_FEATURE_FANCY_HEAD
114 if (argc <= header_threshhold) {
115 header_threshhold = 0;
121 /* Now define some things here to avoid #ifdefs in the code below.
122 * These should optimize out of the if conditions below. */
123 #define header_threshhold 1
124 #define count_bytes 0
128 fp = fopen_or_warn_stdin(*argv);
131 *argv = (char *) bb_msg_standard_input;
133 if (header_threshhold) {
137 while (i && ((c = getc(fp)) != EOF)) {
138 if (count_bytes || (c == '\n')) {
143 if (fclose_if_not_stdin(fp)) {
144 bb_simple_perror_msg(*argv);
145 retval = EXIT_FAILURE;
147 die_if_ferror_stdout();
149 retval = EXIT_FAILURE;
151 fmt = header_fmt_str;
154 fflush_stdout_and_exit(retval);