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author Rob Landley <rob@landley.net>
date Sun, 07 Oct 2012 23:53:25 -0500
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<title>Toybox Roadmap</title>

<h2>Goals and use cases</h2>

<p>We have several potential use cases for a new set of command line
utilities, and are using those to determine which commands to implement
for Toybox's 1.0 release.</p>

<p>Our current candidate list combines the commands toybox already implements,
the development environment command list, the toolbox standard commands,
various vendor configurations of busybox, a selected subset of the SUSv4
standard, a couple of the less-insane bits of LSB, a few outright requests,
plus additional to-be-determined shell functionality.</p>

<p>See the <a href=status.html>status page</a> for the combined list
and progress towards implementing it.</p>

<hr />
<a name="standards">
<h2>Use case: standards compliance.</h2>

<h3>POSIX-2008/SUSv4</h3>
<p>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.)</p>

<p>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.</p>

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

<h3>Problems with the standard</h3>

<p>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.</p>

<p>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.)</p>

<p>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).</p>

<p>Some commands are for a compiler toolchain (ar c99 cflow ctags cxref gencat
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.)</p>

<p>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.)</p>

<p>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.</p>

<p>Removing all of that leaves the following commands, which toybox should
implement:</p>

<blockquote><b>
<span id=posix>
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
</span>
</b></blockquote>

<h3>Linux Standard Base</h3>

<p>One attempt to supplement POSIX towards an actual usable system was the
Linux Standard Base. Unfortunately, the quality of this "standard" is
fairly low.</p>

<p>POSIX allowed its standards process to be compromised
by leaving things out, thus allowing IBM mainframes and Windows NT to drive
a truck through the holes and declare themselves compilant. But it means what
they DID standardize tends to be respected.</p>

<p>The Linux Standard Base's failure mode is different, they respond to
pressure by including special-case crap, such as allowing Red Hat to shoehorn
RPM on the standard even though all sorts of distros (from Debian to Slackware)
don't use it and probably never will. This means anything in the LSB is
at best a suggestion: arbitrary portions of this standard are widely
ignored.</p>

<p>The LSB does specify a <a href=http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/cmdbehav.html>list of command line
utilities</a>:</p>

<blockquote><b>
ar at awk batch bc chfn chsh col cpio crontab df dmesg du echo egrep 
fgrep file fuser gettext grep groupadd groupdel groupmod groups 
gunzip gzip hostname install install_initd ipcrm ipcs killall lpr ls 
lsb_release m4 md5sum mknod mktemp more mount msgfmt newgrp od passwd 
patch pidof remove_initd renice sed sendmail seq sh shutdown su sync 
tar umount useradd userdel usermod xargs zcat
</b></blockquote>

<p>Where posix specifies one of those commands, LSB's deltas tend to be
accomodations for broken tool versions which aren't up to date with the
standard yet. (See <a href=http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/more.html>more</a> and <a href=http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/xargs.html>xargs</a>
for examples.)</p>

<p>Since we've already committed to using our own judgement to skip bits of
POSIX, and LSB's "judgement" in this regard is purely bug workarounds to declare
various legacy tool implementations "compliant", this means we're mostly
interested in the set of tools that aren't specified in posix at all.</p>

<p>Of these, gettext and msgfmt are internationalization, install_initd and
remove_initd aren't present on ubuntu 10.04, lpr is out of scope, and
lsb_release is a distro issue (it's a nice command, but the output of
lsb_release -a is the name and version number of the linux distro you're
running, which toybox doesn't know).</p>

<p>This leaves:</p>

<blockquote><b>
<span id=lsb>
chfn chsh dmesg egrep fgrep groupadd groupdel groupmod groups
gunzip gzip hostname install killall md5sum
mknod mktemp mount passwd pidof sendmail seq shutdown
su sync tar umount useradd userdel usermod zcat
</span>
</b></blockquote>

<hr />
<a name="dev_env">
<h2>Use case: provide a self-hosting development environment</h2>

<p>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
drop-in test environment for toybox. We install both implementations side
by side, redirecting the symlinks a command at a time until the older
package is no longer used, and can be removed.)</p>

<p>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.)</p>

<blockquote><b>
<span id=development>
bzcat cat cp dirname echo env patch rmdir sha1sum sleep sort sync
true uname wc which yes 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 umount vi
</span>
</b></blockquote>

<p>Note: Aboriginal Linux installs bash 2.05b as #!/bin/sh and its scripts
require bash extensions not present in shells such as busybox ash.
This means that toysh needs to supply several bash extensions _and_ work
when called under the name "bash".</p>

<hr />
<a name=toolbox>
<h2>Use case: Replacing Android Toolbox</h2>

<h3>Full toolbox command set</h3>

<p>Here is the full list of toolbox commands:
</p>
<blockquote><b>
alarm cat chmod chown cmp cp date dd df dmesg getevent getprop hd id ifconfig
iftop insmod ioctl kill ln log ls lsmod mkdir mount mv netstat newfs_msdos notify
pidof printenv ps renice rm rmdir rmmod route schedtop sendevent setconsole
setprop sleep smd start stop sync toolbox top umount vmstat watchprops wipe
</b></blockquote>

<p>The following Toolbox commands are reasonably standardized:</p>

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

<h3>Android-specific commands</h3>
<p>Toolbox also provides the following nonstandard commands, which are unique
to Android (or at least do not appear in Ubuntu or SUSv4):</p>

<blockquote><b>
<span id=toolbox>
alarm hd getevent getprop ioctl log nandread notify
r schedtop sendevent setconsole setprop smd watchprops wipe
</span>
</b></blockquote>

<hr />
<h2>Requests:</h2>

<p>The following additional commands have been requested by various users:</p>
<blockquote><b>
<span id=request>
freeramdisk getty halt hexdump hwclock klogd modprobe ping ping6 pivot_root
poweroff sfdisk sudo syslogd taskset telnet telnetd tracepath traceroute unzip
usleep vconfig zip free login modinfo unshare netcat help
</span>
</b></blockquote>

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