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"
20 //usage: "\n -n N[kbm] Print first N lines"
21 //usage: IF_FEATURE_FANCY_HEAD(
22 //usage: "\n -c N[kbm] Print first N bytes"
23 //usage: "\n -q Never print headers"
24 //usage: "\n -v Always print headers"
27 //usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
29 //usage:#define head_example_usage
30 //usage: "$ head -n 2 /etc/passwd\n"
31 //usage: "root:x:0:0:root:/root:/bin/bash\n"
32 //usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
36 /* This is a NOEXEC applet. Be very careful! */
38 static const char head_opts[] ALIGN1 =
40 #if ENABLE_FEATURE_FANCY_HEAD
45 static const struct suffix_mult head_suffixes[] = {
52 #define header_fmt_str "\n==> %s <==\n"
54 int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
55 int head_main(int argc, char **argv)
57 unsigned long count = 10;
59 #if ENABLE_FEATURE_FANCY_HEAD
61 int header_threshhold = 1;
68 int retval = EXIT_SUCCESS;
70 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
71 /* Allow legacy syntax of an initial numeric option without -n. */
72 if (argv[1] && argv[1][0] == '-'
73 && isdigit(argv[1][1])
82 /* No size benefit in converting this to getopt32 */
83 while ((opt = getopt(argc, argv, head_opts)) > 0) {
85 #if ENABLE_FEATURE_FANCY_HEAD
87 header_threshhold = INT_MAX;
90 header_threshhold = -1;
98 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
101 count = xatoul_sfx(p, head_suffixes);
111 *--argv = (char*)"-";
113 fmt = header_fmt_str + 1;
114 #if ENABLE_FEATURE_FANCY_HEAD
115 if (argc <= header_threshhold) {
116 header_threshhold = 0;
122 /* Now define some things here to avoid #ifdefs in the code below.
123 * These should optimize out of the if conditions below. */
124 #define header_threshhold 1
125 #define count_bytes 0
129 fp = fopen_or_warn_stdin(*argv);
132 *argv = (char *) bb_msg_standard_input;
134 if (header_threshhold) {
138 while (i && ((c = getc(fp)) != EOF)) {
139 if (count_bytes || (c == '\n')) {
144 if (fclose_if_not_stdin(fp)) {
145 bb_simple_perror_msg(*argv);
146 retval = EXIT_FAILURE;
148 die_if_ferror_stdout();
150 retval = EXIT_FAILURE;
152 fmt = header_fmt_str;
155 fflush_stdout_and_exit(retval);