In another thread I was cockily saying that any program [which is not part of the OS user interface, like a shell] with names like exit, test or help is stupid. I meant to imply that such common names should be reserved to the top level user interface, usually a command shell or core OS utility.
User schily remarked that help is a command of the sccs version control system which has been an integral part of Unix since the 70s. sccs is in fact included in the Single Unix Specification.
The online documentation of sccs seems ambiguous. Most pages list help as an sccs subcommand, invoked as sccs help <topic>. Then there is a /usr/bin/sccshelp command. But another page indeed lists a dedicated /usr/ccs/bin/help.
I assume that for sccs users /usr/ccs/bin/ would be in the path so that help has been part of many Unix installations for 40 years1. In that case I would argue that even though the choice of command name is regrettable sccs would have seniority and bash should have called its built-in bash-help or the like.
So is it or was it common to have an (sccs) help command in your path?
1 This sounds weird.
Best Answer
The past did not work that way.
You are buying into a somewhat flawed modern model that wasn't the case at the time.
— Mike O'Brien (The Aerospace Corporation) <neat.ai.toronto.edu!pyramid!verdix!ogccse!tektronix!aerospace.aero.org!sequent!aero!obrien> via <haroldh@think.com> (1989-03-01). VAXen, my children, just don't belong some places. rec.humor.funny.Rather famously, Unix didn't not come with a simple help command for beginners. This was a hole (much discussed on on-line discussion fora) that was filled not just once, by the writers of the Bourne Again shell, but several times over. Mortice-Kern provided a
helpcommand that would search for doco to print from ahelpfileusing ahelpindex. AT&T System 5 Release 3.2 had ahelpcommand, too, for example:$ help help:UNIX System On-line Help Choices description s starter: general information l locate:find a command with keyword u usage: information about command g glossary: definition of terms r redirect to a file or a command q Quit Enter choiceThat this was in AT&T Unix rather puts the kibosh on the idea that superseding an SCCS command named
helpis illegitimate or that the writers of the Bourne Again shell were out of step. But there's more.We were expected to actually use
—PATH.login.dfl. Sun Microsystems, Inc.. 2004-06-25.One part of the modern model is that everything goes into one giant directory, be it Daniel J. Bernstein's
/commandor Arch Linux's/usr/bin. This of course causes all of the headaches with different commands namedfastboot(which in other models would be distinguished by being inbin/andsbin/). But that wasn't the model then.The model then is exemplified by the multiple variants of the
lscommand that I discussed and by questions such as "Nexenta bash script uses /usr/sun/bin/sed instead of /usr/bin/sed". There are a whole load of command directories, and what subset of them one chooses to have listed in the value of thePATHenvironment variable, and in what order, determines the personality of the operating system that one sees.The command search path could, and to an extent still can, include things such as:
/binand/usr/bin/— the traditional, pre-dating formal standardization, general toolsets; from a post-formal-standardization viewpoint, commands that conform to the System V Interface Definition and the X/Open Portability Guide version 3/sbinand/usr/sbin/— system administration tools/etc/and/usr/etc/— more system administration tools (Yes Virginia, executables once went in/etc/.)/5binand/usr/5bin/— System V (i.e. 5) compatibility directory with AT&T Unix System 5 compatible tools/usr/ucb/— UCB (i.e. BSD) compatibility directory with BSD-compatible tools/usr/mbin/— multi-byte character set capable variants of/usr/bintools/usr/rbin/— tools made available by an administrator to some "restricted" shells/usr/lbin/— locally-installed tools, a precursor of/usr/local/bin//usr/amdahl/bin/and/usr/sun/bin/— operating system vendor tools, more generally taking the form of/usr/${OEM}/binand from which a parallel can be drawn to/usr/local/bin/usr/games/— games/usr/ccs/bin— various developer tools, as you have observed/usr/xpg4/bin/— the directory with commands that behave in the ways dictated by the X/Open Portability Guide issue 4/usr/xpg6/bin/— the directory with commands that behave in the ways dictated by the notional X/Open Portability Guide issue 6, more properly known as POSIX.1:2001 or the Single Unix Specification version 3/opt/sfw/bin/— created by installing a CD of additional utilities from Sun, now known as the SunFreeware Companion CD/opt/csw/bin/— OpenCSW and Blastwave tools/opt/SUNWspro/bin/— commands from the Sun Workshop (now known as Oracle Developer Studio) tool suite,SUNWbeing Sun's (original) stock exchange ticker code andsprodenoting the old product name SunPro/usr/local/bin/— stuff provided by third parties who do not use an/optsubdirectory or CSWSun/Oracle operating systems, and their open source derivatives, were at their height perhaps the most extreme examples of such multiple personality operating systems. (Oracle has since chucked several of these directories, including
/usr/ucband/usr/ccs, away.) But some of the aforegiven are from AIX and others./usr/amdahl/binis from UTS, for example.What program one ran from a given command name depended from what personality one was choosing. The idea that there was, and must be, only one program for any given command name was daft. After all, differentiating commands of the same names was what
PATHwas for.There was no notion of strict precedence.
Many commands lived and died quite rapidly. Bill Joy created an
iulcommand as a precursor toul, for example. BSD also once had agreekcommand.The idea that a command was set in stone forever, and owned a name to the excusion of shell builtins and others, was fairly foreign, given the turnover in command sets.
Just for starters,
shitself had been variously the Thompson, Mashey, Bourne, and Korn shells within the space of a decade and a bit. The idea that the Thompson shell's externalifcommand prevented the Bourne shell from havingifas a keyword was of course ludicrous.Notice that the (post-2005, ksh93q) AT&T Korn shell's mechanism for enabling extra built-in commands, the inclusion of
/opt/ast/binin the value ofPATH, both supports the notion that built-in commands can supplant external commands of the same names and ties in with the idea that one is expected to usePATHto control personality. (aststands for AT&T Software Technology, by the way.)Further reading
helpcommand". Unix System V, release 3.2: user's guide. Prentice-Hall. 1989. pp. 2–23 et seq./usr— The Mystery Directory". UNIX system administration. Hayden Book Company, ISBN 9780810462892. pp. 54 et seq.if. Manuals. Etsh Project.ul. Proposals.