1 How to Add a New Applet to BusyBox
2 ==================================
4 This document details the steps you must take to add a new applet to BusyBox.
7 Matt Kraai - initial writeup
8 Mark Whitley - the remix
9 Thomas Lundquist - Added stuff for the new directory layout.
14 First, write your applet. Be sure to include copyright information at the
15 top, such as who you stole the code from and so forth. Also include the
16 mini-GPL boilerplate. Be sure to name the main function <applet>_main instead
17 of main. And be sure to put it in <applet>.c. Usage do not have to be taken care of by your applet.
19 For a new applet mu, here is the code that would go in mu.c:
21 ----begin example code------
23 /* vi: set sw=4 ts=4: */
25 * Mini mu implementation for busybox
28 * Copyright (C) [YEAR] by [YOUR NAME] <YOUR EMAIL>
30 * This program is free software; you can redistribute it and/or modify
31 * it under the terms of the GNU General Public License as published by
32 * the Free Software Foundation; either version 2 of the License, or
33 * (at your option) any later version.
35 * This program is distributed in the hope that it will be useful,
36 * but WITHOUT ANY WARRANTY; without even the implied warranty of
37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
38 * General Public License for more details.
40 * You should have received a copy of the GNU General Public License
41 * along with this program; if not, write to the Free Software
42 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
49 int mu_main(int argc, char **argv)
54 if ((fd = open("/dev/random", O_RDONLY)) < 0)
55 perror_msg_and_die("/dev/random");
57 if ((n = safe_read(fd, &mu, 1)) < 1)
58 perror_msg_and_die("/dev/random");
63 ----end example code------
69 Before you submit your applet for inclusion in BusyBox, (or better yet, before
70 you _write_ your applet) please read through the style guide in the docs
71 directory and make your program compliant.
77 As you are writing your applet, please be aware of the body of pre-existing
78 useful functions in libbb. Use these instead of reinventing the wheel.
80 Additionally, if you have any useful, general-purpose functions in your
81 program that could be useful in another program, consider putting them in
88 Find the appropriate directory for your new applet.
90 Make sure you find the appropriate places in the files, the applets are
91 sorted alphabetically.
93 Add the applet to Makefile.in in the chosen applet directory:
95 obj-$(CONFIG_MU) += mu.o
97 Add the applet to Config.in in the chosen applet directory:
103 Returns an indeterminate value.
109 Next, add usage information for you applet to include/usage.h.
110 This should look like the following:
112 #define mu_trivial_usage \
114 #define mu_full_usage \
115 "Returns an indeterminate value.\n\n" \
117 "\t-a\t\tfirst function\n" \
118 "\t-b\t\tsecond function\n" \
120 If your program supports flags, the flags should be mentioned on the first
121 line (-[abcde]) and a detailed description of each flag should go in the
122 mu_full_usage section, one flag per line. (Numerous examples of this
123 currently exist in usage.h.)
129 Next, add an entry to include/applets.h. Be *sure* to keep the list
130 in alphabetical order, or else it will break the binary-search lookup
131 algorithm in busybox.c and the Gods of BusyBox smite you. Yea, verily:
133 /* all programs above here are alphabetically "less than" 'mu' */
135 APPLET("mu", mu_main, _BB_DIR_USR_BIN, mu_usage)
137 /* all programs below here are alphabetically "greater than" 'mu' */
140 Finally, add a define for your applet to include/config.h
148 If you're feeling especially nice, you should also document your applet in the
149 docs directory (but nobody ever does that).
151 Adding some text to docs/Configure.help is a nice start.
154 The Grand Announcement
155 ----------------------
157 Then create a diff -urN of the files you added (<appletdir/><applet>.c,
158 include/usage.c, include/applets.h, include/config.h, <appletdir>/Makefile.in, <appletdir>/config.in)
159 and send it to the mailing list:
162 Sending patches as attachments is preferred, but not required.