133 lines
6.0 KiB
Plaintext
133 lines
6.0 KiB
Plaintext
# vi: set sw=4 ts=4:
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=head1 NAME
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BusyBox - The Swiss Army Knife of Embedded Linux
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=head1 SYNTAX
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BusyBox <function> [arguments...] # or
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<function> [arguments...] # if symlinked
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=head1 DESCRIPTION
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BusyBox combines tiny versions of many common UNIX utilities into a single
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small executable. It provides minimalist replacements for most of the utilities
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you usually find in GNU coreutils, util-linux, etc. The utilities in BusyBox
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generally have fewer options than their full-featured GNU cousins; however, the
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options that are included provide the expected functionality and behave very
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much like their GNU counterparts.
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BusyBox has been written with size-optimization and limited resources in mind.
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It is also extremely modular so you can easily include or exclude commands (or
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features) at compile time. This makes it easy to customize your embedded
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systems. To create a working system, just add /dev, /etc, and a Linux kernel.
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BusyBox provides a fairly complete POSIX environment for any small or embedded
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system.
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BusyBox is extremely configurable. This allows you to include only the
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components you need, thereby reducing binary size. Run 'make config' or 'make
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menuconfig' to select the functionality that you wish to enable. The run
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'make' to compile BusyBox using your configuration.
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After the compile has finished, you should use 'make install' to install
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BusyBox. This will install the '/bin/busybox' binary, and will also create
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symlinks pointing to the '/bin/busybox' binary for each utility that you
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compile into BusyBox. By default, 'make install' will place these symlinks
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into the './_install' directory, unless you have defined 'PREFIX', thereby
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specifying some alternative location (i.e., 'make PREFIX=/tmp/foo install').
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If you wish to install using hardlinks, rather than the default of using
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symlinks, you can use 'make PREFIX=/tmp/foo install-hardlinks' instead.
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=head1 USAGE
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BusyBox is a multi-call binary. A multi-call binary is an executable program
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that performs the same job as more than one utility program. That means there
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is just a single BusyBox binary, but that single binary acts like a large
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number of utilities. This allows BusyBox to be smaller since all the built-in
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utility programs (we call them applets) can share code for many common operations.
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You can also invoke BusyBox by issuing a command as an argument on the
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command line. For example, entering
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/bin/busybox ls
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will also cause BusyBox to behave as 'ls'.
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Of course, adding '/bin/busybox' into every command would be painful. So most
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people will invoke BusyBox using links to the BusyBox binary.
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For example, entering
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ln -s /bin/busybox ls
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./ls
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will cause BusyBox to behave as 'ls' (if the 'ls' command has been compiled
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into BusyBox). Generally speaking, you should never need to make all these
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links yourself, as the BusyBox build system will do this for you when you run
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the 'make install' command.
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If you invoke BusyBox with no arguments, it will provide you with a list of the
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applets that have been compiled into your BusyBox binary.
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=head1 COMMON OPTIONS
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Most BusyBox commands support the B<--help> argument to provide a terse runtime
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description of their behavior. If the CONFIG_FEATURE_VERBOSE_USAGE option has
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been enabled, more detailed usage information will also be available.
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=head1 COMMANDS
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Currently defined functions include:
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addgroup, adduser, adjtimex, ar, arping, ash, awk, basename, bunzip2,
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busybox, bzcat, cal, cat, chgrp, chmod, chown, chroot, chvt, clear, cmp,
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cp, cpio, crond, crontab, cut, date, dc, dd, deallocvt, delgroup, deluser,
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devfsd, df, dirname, dmesg, dos2unix, dpkg, dpkg-deb, du, dumpkmap,
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dumpleases, echo, egrep, env, expr, false, fbset, fdflush, fdformat, fdisk,
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fgrep, find, fold, free, freeramdisk, fsck.minix, ftpget, ftpput, getopt,
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getty, grep, gunzip, gzip, halt, hdparm, head, hexdump, hostid, hostname,
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httpd, hush, hwclock, id, ifconfig, ifdown, ifup, inetd, init, insmod,
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install, ip, ipcalc, iplink, iproute, iptunnel, kill, killall, klogd, lash,
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last, length, linuxrc, ln, loadfont, loadkmap, logger, login, logname,
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logread, losetup, ls, lsmod, makedevs, md5sum, mesg, mkdir, mkfifo,
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mkfs.minix, mknod, mkswap, mktemp, modprobe, more, mount, msh, mt, mv,
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nameif, nc, netstat, nslookup, od, openvt, passwd, patch, pidof, ping,
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ping6, pipe_progress, pivot_root, poweroff, printf, ps, pwd, rdate,
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readlink, realpath, reboot, renice, reset, rm, rmdir, rmmod, route, rpm,
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rpm2cpio, run-parts, rx, sed, seq, setkeycodes, sha1sum, sleep, sort,
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start-stop-daemon, strings, stty, su, sulogin, swapoff, swapon, sync,
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sysctl, syslogd, tail, tar, tee, telnet, telnetd, test, tftp, time, top,
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touch, tr, traceroute, true, tty, udhcpc, udhcpd, umount, uname,
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uncompress, uniq, unix2dos, unzip, uptime, usleep, uudecode, uuencode,
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vconfig, vi, vlock, watch, watchdog, wc, wget, which, who, whoami, xargs,
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yes, zcat
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=head1 LIBC NSS
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GNU Libc (glibc) uses the Name Service Switch (NSS) to configure the behavior
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of the C library for the local environment, and to configure how it reads
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system data, such as passwords and group information. This is implemented
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using an /etc/nsswitch.conf configuration file, and using one or more of the
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/lib/libnss_* libraries. BusyBox tries to avoid using any libc calls that make
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use of NSS. Some applets however, such as login and su, will use libc functions
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that require NSS.
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If you enable CONFIG_USE_BB_PWD_GRP, BusyBox will use internal functions to
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directly access the /etc/passwd, /etc/group, and /etc/shadow files without
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using NSS. This may allow you to run your system without the need for
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installing any of the NSS configuration files and libraries.
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When used with glibc, the BusyBox 'networking' applets will similarly require
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that you install at least some of the glibc NSS stuff (in particular,
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/etc/nsswitch.conf, /lib/libnss_dns*, /lib/libnss_files*, and /lib/libresolv*).
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Shameless Plug: As an alternative, one could use a C library such as uClibc. In
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addition to making your system significantly smaller, uClibc does not require the
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use of any NSS support files or libraries.
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=over 4
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