busybox.sgml

手机嵌入式Linux下可用的busybox源码

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [ ]>
<book id="BusyBoxDocumentation">
 <bookinfo>
  <title>BusyBox - The Swiss Army Knife of Embedded Linux</title>
  
  <legalnotice>
   <para>
     This documentation is free software; you can redistribute
     it and/or modify it under the terms of the GNU General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later
     version.
   </para>
      
   <para>
     This program is distributed in the hope that it will be
     useful, but WITHOUT ANY WARRANTY; without even the implied
     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     See the GNU General Public License for more details.
   </para>
      
   <para>
     You should have received a copy of the GNU General Public
     License along with this program; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
     MA 02111-1307 USA
   </para>
      
   <para>
     For more details see the file COPYING in the source
     distribution of Linux.
   </para>
  </legalnotice>
 </bookinfo>

<toc></toc>
  <chapter id="Introduction">
     <title>Introduction</title>

	<para>
	BusyBox combines tiny versions of many common UNIX utilities into a single
	small executable. It provides minimalist replacements for most of the
	utilities you usually find in fileutils, shellutils, findutils, textutils,
	grep, gzip, tar, etc. BusyBox provides a fairly complete POSIX environment
	for any small or embedded system. The utilities in BusyBox generally have
	fewer options than their full-featured GNU cousins; however, the options
	that are included provide the expected functionality and behave very much
	like their GNU counterparts. 
	</para>

	<para>
	BusyBox has been written with size-optimization and limited resources in
	mind. It is also extremely modular so you can easily include or exclude
	commands (or features) at compile time. This makes it easy to customize
	your embedded systems. To create a working system, just add a kernel, a
	shell (such as ash), and an editor (such as elvis-tiny or ae).
	</para>
  </chapter>

  <chapter id="Syntax">
     <title>How to use BusyBox</title>
	<sect1 id="How-to-use-BusyBox">
	    <title>Syntax</title>

	    <para>
	    <screen>
	     BusyBox &lt;function&gt; [arguments...]  # or
	    </screen>
	    </para>

	    <para>
	    <screen>
	     &lt;function&gt; [arguments...]          # if symlinked
	    </screen>
	    </para>
	</sect1>

	<sect1 id="Invoking-BusyBox">
	    <title>Invoking BusyBox</title>

	    <para>
	    When you create a link to BusyBox for the function you wish to use, when
	    BusyBox is called using that link it will behave as if the command itself
	    has been invoked.
	    </para>

	    <para>
	    For example, entering
	    </para>

	    <para>
	    <screen>
		    ln -s ./BusyBox ls
		    ./ls
	    </screen>
	    </para>

	    <para>
	    will cause BusyBox to behave as 'ls' (if the 'ls' command has been compiled
	    into BusyBox). 
	    </para>

	    <para>
	    You can also invoke BusyBox by issuing the command as an argument on the
	    command line. For example, entering
	    </para>

	    <para>
	    <screen>
		    ./BusyBox ls
	    </screen>
	    </para>

	    <para>
	    will also cause BusyBox to behave as 'ls'. 
	    </para>

	</sect1>

	<sect1 id="Common-options">
	    <title>Common options</title>

	    <para>
	    Most BusyBox commands support the <emphasis>--help</emphasis> option to provide 
	    a terse runtime description of their behavior. 
	    </para>
	</sect1>
  </chapter>

  <chapter id="Commands">
     <title>BusyBox Commands</title>
	<sect1 id="Available-BusyBox-Commands">
	    <title>Available BusyBox Commands</title>
		<para>
		Currently defined functions include:
		</para>

		<para>
		ar, basename, cat, chgrp, chmod, chown, chroot, chvt, clear,
		cp, cut, date, dc, dd, deallocvt, df, dirname, dmesg, dpkg-deb,
		du, dumpkmap, dutmp, echo, false, fbset, fdflush, find, free,
		freeramdisk, fsck.minix, grep, gunzip, gzip, halt, head,
		hostid, hostname, id, init, insmod, kill, killall, length, ln,
		loadacm, loadfont, loadkmap, logger, logname, ls, lsmod,
		makedevs, mkdir, mkfifo, mkfs.minix, mknod, mkswap, mktemp,
		more, mount, mt, mv, nc, nslookup, ping, poweroff, printf, ps,
		pwd, reboot, renice, reset, rm, rmdir, rmmod, sed, setkeycodes, sh, sleep,
		sort, swapoff, swapon, sync, syslogd, tail, tar, tee, telnet,
		test, touch, tr, true, tty, umount, uname, uniq, update,
		uptime, usleep, uudecode, uuencode, wc, which, whoami, yes,
		zcat, [
		</para>
	</sect1>

	<sect1 id="ar">
	    <title>ar</title>

		<para>
		Usage: ar [OPTION] archive [FILENAME]...
		</para>

		<para>
		Extract or list files from an ar archive.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			o	Preserve original dates
			p	Extract to stdout
			t	List
			x	Extract
			v	Verbosely list files processed
		</screen>
		</para>
	</sect1>

	<sect1 id="basename">
	    <title>basename</title>
		<para>
		Usage: basename FILE [SUFFIX]
		</para>

		<para>
		Strip directory path and suffixes from FILE. If specified, also removes
		any trailing SUFFIX.
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ basename /usr/local/bin/foo
			foo
			$ basename /usr/local/bin/
			bin
			$ basename /foo/bar.txt .txt
			bar
		</screen>
		</para>
	</sect1>

	<sect1 id="cat">
	    <title>cat</title>

		<para>
		Usage: cat [FILE]...
		</para>

		<para>
		Concatenate <literal>FILE(s)</literal> and prints them to the standard
		output.
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ cat /proc/uptime
			110716.72 17.67
		</screen>
		</para>
	</sect1>

	<sect1 id="chgrp">
	    <title>chgrp</title>

		<para>
		Usage: chgrp [OPTION]... GROUP FILE...
		</para>

		<para>
		Change the group membership of each FILE to GROUP.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			-R      Change files and directories recursively
		</screen>
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ ls -l /tmp/foo
			-r--r--r--    1 andersen andersen        0 Apr 12 18:25 /tmp/foo
			$ chgrp root /tmp/foo
			$ ls -l /tmp/foo
			-r--r--r--    1 andersen root            0 Apr 12 18:25 /tmp/foo
		</screen>
		</para>
	</sect1>

	<sect1 id="chmod">
	    <title>chmod</title>

		<para>
		Usage: chmod [<emphasis>-R</emphasis>] MODE[,MODE]... FILE...
		</para>

		<para>
		Change file access permissions for the specified
		<literal>FILE(s)</literal> (or directories). Each MODE is defined by
		combining the letters for WHO has access to the file, an OPERATOR for
		selecting how the permissions should be changed, and a PERMISSION for
		<literal>FILE(s)</literal> (or directories).
		</para>

		<para>
		WHO may be chosen from
		</para>

		<para>
		<screen>
			u       User who owns the file
			g       Users in the file's Group
			o       Other users not in the file's group
			a       All users
		</screen>
		</para>

		<para>
		OPERATOR may be chosen from
		</para>

		<para>
		<screen>
			+       Add a permission
			-       Remove a permission
			=       Assign a permission
		</screen>
		</para>

		<para>
		PERMISSION may be chosen from
		</para>

		<para>
		<screen>
			r       Read
			w       Write
			x       Execute (or access for directories)
			s       Set user (or group) ID bit
			t       Sticky bit (for directories prevents removing files by non-owners)
		</screen>
		</para>

		<para>
		Alternately, permissions can be set numerically where the first three
		numbers are calculated by adding the octal values, such as
		</para>

		<para>
		<screen>
			4       Read
			2       Write
			1       Execute
		</screen>
		</para>

		<para>
		An optional fourth digit can also be used to specify
		</para>

		<para>
		<screen>
			4       Set user ID
			2       Set group ID
			1       Sticky bit
		</screen>
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			-R      Change files and directories recursively.
		</screen>
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ ls -l /tmp/foo
			-rw-rw-r--    1 root     root            0 Apr 12 18:25 /tmp/foo
			$ chmod u+x /tmp/foo
			$ ls -l /tmp/foo
			-rwxrw-r--    1 root     root            0 Apr 12 18:25 /tmp/foo*
			$ chmod 444 /tmp/foo
			$ ls -l /tmp/foo
			-r--r--r--    1 root     root            0 Apr 12 18:25 /tmp/foo
		</screen>
		</para>
	</sect1>
	
	<sect1 id="chown">
	    <title>chown</title>
		<para>
		Usage: chown [OPTION]... OWNER[&lt;.|:&gt;[GROUP] FILE...
		</para>

		<para>
		Change the owner and/or group of each FILE to OWNER and/or GROUP.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			-R      Change files and directories recursively
		</screen>
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ ls -l /tmp/foo
			-r--r--r--    1 andersen andersen        0 Apr 12 18:25 /tmp/foo
			$ chown root /tmp/foo
			$ ls -l /tmp/foo
			-r--r--r--    1 root     andersen        0 Apr 12 18:25 /tmp/foo
			$ chown root.root /tmp/foo
			ls -l /tmp/foo
			-r--r--r--    1 root     root            0 Apr 12 18:25 /tmp/foo
		</screen>
		</para>
	</sect1>

	<sect1 id="chroot">
	    <title>chroot</title>
		<para>
		Usage: chroot NEWROOT [COMMAND...]
		</para>

		<para>
		Run COMMAND with root directory set to NEWROOT.
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ ls -l /bin/ls
			lrwxrwxrwx    1 root     root          12 Apr 13 00:46 /bin/ls -&gt; /BusyBox
			$ mount /dev/hdc1 /mnt -t minix
			$ chroot /mnt
			$ ls -l /bin/ls
			-rwxr-xr-x    1 root     root        40816 Feb  5 07:45 /bin/ls*
		</screen>
		</para>
	</sect1>

	<sect1 id="chvt">
	    <title>chvt</title>
		<para>
		Usage: chvt N
		</para>

		<para>
		Change the foreground virtual terminal to /dev/ttyN
		</para>
	</sect1>

	<sect1 id="clear">
	    <title>clear</title>

		<para>
		Usage: clear
		</para>

		<para>
		Clear the screen.
		</para>
	</sect1>

	<sect1 id="cp">
	    <title>cp</title>

		<para>
		Usage: cp [OPTION]... SOURCE DEST
		</para>

		<para>
		<screen>
		   or: cp [OPTION]... SOURCE... DIRECTORY
		</screen>
		</para>

		<para>
		Copy SOURCE to DEST, or multiple <literal>SOURCE(s)</literal> to
		DIRECTORY.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			-a      Same as -dpR
			-d      Preserve links
			-p      Preserve file attributes if possible
			-R      Copy directories recursively
		</screen>
		</para>
	</sect1>

	<sect1 id="cut">
	    <title>cut</title>

		<para>
		Usage: cut [OPTION]... [FILE]...
		</para>

		<para>
		Print selected fields from each input FILE to standard output.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
				-b LIST Output only bytes from LIST
				-c LIST Output only characters from LIST
				-d CHAR Use CHAR instead of tab as the field delimiter
				-s      Output only the lines containing delimiter
				-f N    Print only these fields
				-n      Ignored
		</screen>
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ echo "Hello world" | cut -f 1 -d ' '
			Hello
			$ echo "Hello world" | cut -f 2 -d ' '
			world
		</screen>
		</para>
	</sect1>

	<sect1 id="date">
	    <title>date</title>

		<para>
		Usage: date [OPTION]... [+FORMAT]
		</para>

		<para>
		<screen>
		  or:  date [OPTION] [MMDDhhmm[[CC]YY][.ss]]
		</screen>
		</para>

		<para>
		Display the current time in the given FORMAT, or set the system date.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			-R      Output RFC-822 compliant date string
			-s      Set time described by STRING
			-u      Print or set Coordinated Universal Time
		</screen>
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ date
			Wed Apr 12 18:52:41 MDT 2000
		</screen>
		</para>
	</sect1>

	<sect1 id="dc">
	    <title>dc</title>

		<para>
		Usage: dc [EXPRESSION]
		</para>

		<para>
		This is a Tiny RPN calculator that understands the
		following operations: +, -, /, *, and, or, not, eor. If
		no arguments are given, dc will process input from
		stdin.
		</para>

		<para>
		The behaviour of BusyBox/dc deviates (just a little ;-)
		from GNU/dc, but this will be remedied in the future.
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ dc 2 2 +
			4
			$ dc 8 8 \* 2 2 + /
			16
			$ dc 0 1 and
			0
			$ dc 0 1 or
			1
			$ echo 72 9 div 8 mul | dc
			64
		</screen>
		</para>
	</sect1>

	<sect1 id="dd">
	    <title>dd</title>

		<para>
		Usage: dd [OPTION]...
		</para>

		<para>
		Copy a file, converting and formatting according to
		options.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			if=FILE Read from FILE instead of stdin
			of=FILE Write to FILE instead of stdout
			bs=N    Read and write N bytes at a time
			count=N Copy only N input blocks
			skip=N  Skip N input blocks
			seek=N  Skip N output blocks
		</screen>
		</para>

		<para>
		Numbers may be suffixed by w (x2), k (x1024), b (x512),
		or M (x1024^2).
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4
			4+0 records in
			4+0 records out
		</screen>
		</para>
	</sect1>

	<sect1 id="deallocvt">
	    <title>deallocvt</title>

		<para>
		Usage: deallocvt N
		</para>

		<para>
		Deallocate unused virtual terminal /dev/ttyN.
		</para>
	</sect1>

	<sect1 id="df">
	    <title>df</title>

		<para>
		Usage: df [FILE]...
		</para>

		<para>
		Print the filesystem space used and space available.
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ df
			Filesystem           1k-blocks      Used Available Use% Mounted on
			/dev/sda3              8690864   8553540    137324  98% /
			/dev/sda1                64216     36364     27852  57% /boot
			$ df /dev/sda3
			Filesystem           1k-blocks      Used Available Use% Mounted on
			/dev/sda3              8690864   8553540    137324  98% /
		</screen>
		</para>
	</sect1>
	
	<sect1 id="dirname">
	    <title>dirname</title>

		<para>
		Usage: dirname NAME
		</para>

		<para>
		Strip non-directory suffix from NAME.
		</para>

		<para>
		Example:
		</para>

		<para>
		<screen>
			$ dirname /tmp/foo
			/tmp
			$ dirname /tmp/foo/
			/tmp
		</screen>
		</para>
	</sect1>

	<sect1 id="dmesg">
	    <title>dmesg</title>

		<para>
		Usage: dmesg [OPTION]...
		</para>

		<para>
		Print or control the kernel ring buffer.
		</para>

		<para>
		Options:
		</para>

		<para>
		<screen>
			-c		Clear the ring buffer after printing
			-n LEVEL	Set the console logging level to LEVEL
			-s BUFSIZE	Query ring buffer using a buffer of BUFSIZE
		</screen>
		</para>
	</sect1>

	<sect1 id="dos2unix">