Busybox replacement

This page has information about the commands and features desired for a busybox replacement program.

See Busybox replacement project for the project proposal for this work.

Command List
We have several potential use cases for a busybox replacement, and are using those to determine a consensus on which commands to target for a 1.0 release of an unencumbered busybox replacement package.

Our current candidate list combines the commands toybox already implements, the development environment command list, the toolbox standard commands, the Sony configuration of busybox, and the selected subset of the SUSv4 standard.

Thus the first release of a busybox replacement should include the following commands:

at awk basename bc bunzip2 bzcat bzip2 cal cat catv chgrp chmod chown chroot chvt cksum cmp comm count cp cpio csplit cut date dd df diff dirname dmesg dnsdomainname du echo egrep env expand expr false fgrep file find fold freeramdisk ftpd ftpget ftpput fuser getconf getty grep gunzip gzip halt hd head help hostname id ifconfig iftop init insmod install ioctl ionice join kill killall klogd less link ln logger login logname losetup ls lsmod lsof man md5sum mdev mkdir mkfifo mknod mkswap mktemp modprobe more mount mountpoint mv nc netcat netstat newgrp newfs_msdos nice nl nohup notify od oneit paste patch pathchk pgrep pidof ping ping6 pivot_root pkill poweroff printenv printf ps pwd readlink reboot renice rm rmdir rmmod route sed seq setsid sfdisk sh sha1sum sleep sort split start stat stop stty swapoff swapon switch_root sync syslogd tabs tac tail tar taskset tee telnet telnetd test time top touch tput tr true truncate tty umount uname unexpand uniq unlink unshare uptime usleep uudecode uuencode vconfig vi vmstat wc wget which who whoami xargs yes zcat

Plus additional to-be-determined shell functionality.

Toybox currently implements
The triaged toybox (2 clause BSD license) is currently implementing usable versions of:

bzcat cal cat catv chroot chvt cksum count cp df dirname dmesg echo false help link mkswap nc netcat nice nohup oneit patch pwd rmdir seq setsid sha1sum sleep sort sync tee true truncate tty uname unlink unshare wc which yes

And contains partial implementations of: mdev sh

See the Toybox todo list for the most up to date status.

Use case: provide a self-hosting development environment
The following commands are enough to build the Aboriginal Linux development environment, boot it to a shell prompt, and build Linux From Scratch 6.8 under it. (Aboriginal Linux currently uses BusyBox for this, thus provides a corresponding test environment for toybox.)

This use case includes running init scripts and other shell scripts, running configure, make, and install in each package, and providing basic command line facilities such as a text editor. (It does not include a compiler toolchain or C library, those are outside the scope of this project.)

Already in toybox
bzcat cat cp dirname echo patch rmdir sha1sum sleep sort sync true uname wc which yes env

Additional commands for development environment
zcat awk basename bzip2 chmod chown cmp cut date dd diff egrep expr find grep gzip head hostname id install ln ls mkdir mktemp mv od readlink rm sed sh tail tar touch tr uniq wget whoami xargs chgrp comm gunzip less logname man split tee test time bunzip2 chgrp chroot comm cpio dmesg dnsdomainname ftpd ftpget ftpput gunzip ifconfig init less logname losetup man mdev mount mountpoint nc pgrep pkill pwd route split stat switch_root tac tee test time umount vi

Note: Aboriginal Linux installs bash 2.05b as #!/bin/sh and its scripts require bash extensions not present in busybox ash.

Standard commands
Toolbox in Android (what version?) implements the following standard commands:

date id uptime ifconfig start stop newfs_msdos ls route netstat ioctl reboot cmp insmod chmod cat lsmod chown df top printenv ionice rmmod sleep notify iftop rmdir dd vmstat hd rm mount ln lsof ps dmesg renice kill mkdir mv sync umount

Android-specific commands
Toolbox also provides the following nonstandard commands, which are unique to Android (or at least do not appear in Ubuntu or SUSv4):

alarm schedtop getprop log setprop watchprops notify wipe getevent sendevent nandread smd setconsole r ioctl

default 1.10 build
A default build of Busybox 1.10 has the following commands:

[, [[, addgroup, adduser, adjtimex, ar, arp, arping, ash,	awk, basename, bunzip2, bzcat, bzip2, cal, cat, catv,	chattr, chgrp, chmod, chown, chpasswd, chpst, chroot,	chrt, chvt, cksum, clear, cmp, comm, cp, cpio, crond,	crontab, cryptpw, cut, date, dc, dd, deallocvt, delgroup,	deluser, df, dhcprelay, diff, dirname, dmesg, dos2unix,	du, dumpkmap, dumpleases, echo, ed, egrep, eject, env,	envdir, envuidgid, expand, expr, false, fbset, fdflush,	fdformat, fdisk, fgrep, find, fold, free, freeramdisk,	fsck, fsck.minix, fuser, getopt, getty, grep, gunzip,	gzip, halt, hdparm, head, hexdump, hostid, hostname, hwclock,	id, ifconfig, ifdown, ifup, inetd, init, insmod, install,	ip, ipaddr, ipcalc, ipcrm, ipcs, iplink, iproute, iprule,	iptunnel, kbd_mode, kill, killall, killall5, klogd, last,	length, less, linux32, linux64, linuxrc, ln, loadfont,	loadkmap, logger, login, logname, logread, losetup, lpd,	lpq, lpr, ls, lsattr, lsmod, lzmacat, makedevs, md5sum,	mdev, mesg, microcom, mkdir, mkfifo, mkfs.minix, mknod,	mkswap, mktemp, modprobe, more, mount, mountpoint, mt,	mv, nameif, netstat, nice, nmeter, nohup, nslookup, od,	openvt, passwd, patch, pgrep, pidof, ping, pipe_progress,	pivot_root, pkill, poweroff, printenv, printf, ps, pscan,	pwd, raidautorun, rdate, readlink, readprofile, realpath,	reboot, renice, reset, resize, rm, rmdir, rmmod, route,	rpm, rpm2cpio, run-parts, runlevel, runsv, runsvdir, rx,	script, sed, sendmail, seq, setarch, setconsole, setkeycodes,	setlogcons, setsid, setuidgid, sh, sha1sum, sleep, softlimit,	sort, split, start-stop-daemon, stat, strings, stty, su,	sulogin, sum, sv, svlogd, swapoff, swapon, switch_root,	sync, sysctl, syslogd, tac, tail, tar, taskset, tee, telnetd,	test, time, top, touch, tr, true, tty, ttysize, udhcpc,	udhcpd, umount, uname, uncompress, unexpand, uniq, unix2dos,	unlzma, unzip, uptime, usleep, uudecode, uuencode, vi,	vlock, watch, watchdog, wc, wget, which, who, whoami,	xargs, yes, zcat

Sony CE Linux (internal distribution) 1.13.4 build
This is from a version of busybox used in lots of Sony products: Currently defined functions: [, [[, ash, basename, bunzip2, bzcat, cat, chgrp, chmod, chown,       chroot, cmp, cp, cpio, cut, date, dd, dirname, dmesg, echo, egrep,        env, expr, false, fgrep, freeramdisk, ftpget, ftpput, getty, grep,        gunzip, gzip, halt, ifconfig, insmod, kill, killall, klogd, ln,        logger, login, ls, lsmod, md5sum, mkdir, mkfifo, mknod, mktemp,        modprobe, mount, mv, pidof, ping, ping6, pivot_root, poweroff,        pwd, readlink, reboot, rm, rmdir, rmmod, route, sed, sfdisk, sh,        sha1sum, sleep, sort, stty, swapoff, swapon, switch_root, sync,        syslogd, tail, tar, taskset, telnet, telnetd, test, touch, true,        umount, uname, uniq, usleep, vconfig, wc, xargs, zcat

POSIX-2008/SUSv4
The best standards are the kind that describe reality, rather than attempting to impose a new one. (I.E. a good standard should document, not legislate.)

The kind of standards which describe existing reality tend to be approved by more than one standards body, such ANSI and ISO both approving C. That's why the IEEE POSIX committee's 2008 standard, the Single Unix Specification version 4, and the Open Group Base Specification edition 7 are all the same standard from three sources.

The [http://opengroup.org/onlinepubs/9699919799/idx/utilities.html "utilities" section] these standards is devoted to the unix command line, and are the best such standard for our purposes. (BusyBox was implemented with regard to SUSv3, an earlier version of this standard.)

Problems with the standard
Unfortunately, these standards describe a subset of reality, lacking any mention of commands such as init, login, or mount required to actually boot a system. It provides ipcrm and ipcs, but not ipcmk, so you can use System V IPC resources but not create them.

These standards also contain a large number of commands that are inappropriate for toybox to implement in its 1.0 release. (Perhaps some of these could be reintroduced in later releases, but not now.)

Starting with the full "utilities" list, we first remove generally obsolete commands (compess ed ex pr uncompress uccp uustat uux), commands for the pre-CVS "SCCS" source control system (admin delta get prs rmdel sact sccs unget val what), fortran support (asa fort77), and batch processing support (batch qalter qdel qhold qmove qmsg qrerun qrls qselect qsig qstat qsub).

Some commands are for a compiler toolchain (ar c99 cflow ctags cxref getcat iconv lex m4 make nm strings strip tsort yacc), which is outside of toybox's mandate and should be supplied externally. (Again, some of these may be revisited later, but not for toybox 1.0.)

Some commands are part of a command shell, and cannot be implemented as separate executables (alias bg cd command fc fg getopts hash jobs kill read type ulimit umask unalias wait). These may be revisited as part of a built-in toybox shell, but are not exported into $PATH via symlinks. (If you fork a child process and have it "cd" then exit, you've accomplished nothing.)

A few other commands are judgement calls, providing command-line internationalization support (iconv locale localedef), System V inter-process communication (ipcrm ipcs), and cross-tty communication from the minicomputer days (talk mesg write). The "pax" utility was supplanted by tar, "mailx" is a command line email client, and "lp" submits files for printing to... what exactly? (cups?) The standard defines crontab but not crond.

Removing all of that leaves the following commands, which toybox should implement:

at awk basename bc cal cat chgrp chmod chown cksum cmp comm cp csplit cut date dd df diff dirname du echo env expand expr false file find fold fuser getconf grep head id join kill link ln logger logname ls man mkdir mkfifo more mv newgrp nice nl nohup od paste patch pathchk printf ps pwd renice rm rmdir sed sh sleep sort split stty tabs tail tee test time touch tput tr true tty uname unexpand uniq unlink uudecode uuencode vi wc who xargs zcat

Can implement incrementally
Rob wrote:

One nice thing about busybox/toybox/toolbox is you can install multiple implementations side by side, and have what symlinks you create (or what comes first in the $PATH) determine who is implementing what.

This allows gradual transitions. Each release, we replace a couple more commands from the old one, until the old one finally isn't being used for anything anymore and we can uninstall it...