14 Jul
2016
14 Jul
'16
1:18 p.m.
I remember hearing that originally the Unix shell had control structures
(e.g. if, while, case) implemented through external commands. However,
I can't see this reflected in the source code. The 7th Edition Bourne
shell has these commands built-in (usr/src/cmd/sh/cmd.c), while the 6th
Edition (usr/source/s2/sh.c) seems to lack them completely.
The only external command I found was glob, which performed wildcard
expansion.
Am I missing something? Was this implemented in a version that was
never released? If so, does anyone know how this implementation worked?
(Nested commands might require holding some sort of globally
accessible stack.)
14 Jul
14 Jul
1:23 p.m.
Could you be confusing the fact the true and false were implemented by
external commands in some early shell's
On Thu, Jul 14, 2016 at 9:18 AM, Diomidis Spinellis <dds(a)aueb.gr> wrote:
I remember hearing that originally the Unix shell had
control structures
(e.g. if, while, case) implemented through external commands. However, I
can't see this reflected in the source code. The 7th Edition Bourne shell
has these commands built-in (usr/src/cmd/sh/cmd.c), while the 6th Edition
(usr/source/s2/sh.c) seems to lack them completely.
The only external command I found was glob, which performed wildcard
expansion.
Am I missing something? Was this implemented in a version that was never
released? If so, does anyone know how this implementation worked? (Nested
commands might require holding some sort of globally accessible stack.)
2:12 p.m.
I thought the V6 Mashey shell didn't have anything built in, but there
were external commands such as goto that would seek the open file
descriptor to a location matching a label, which would be a comment
(beginning with a colon, which was a no-op command.) There would also
have been an "if" command or option to goto or something.
On 07/14/2016 06:23 AM, Clem Cole wrote:
Could you be confusing the fact the true and false
were implemented by
external commands in some early shell's
On Thu, Jul 14, 2016 at 9:18 AM, Diomidis Spinellis <dds(a)aueb.gr
<mailto:dds@aueb.gr>> wrote:
I remember hearing that originally the Unix shell had control
structures (e.g. if, while, case) implemented through external
commands. However, I can't see this reflected in the source
code. The 7th Edition Bourne shell has these commands built-in
(usr/src/cmd/sh/cmd.c), while the 6th Edition (usr/source/s2/sh.c)
seems to lack them completely.
The only external command I found was glob, which performed
wildcard expansion.
Am I missing something? Was this implemented in a version that
was never released? If so, does anyone know how this
implementation worked? (Nested commands might require holding
some sort of globally accessible stack.)
10:36 p.m.
On Thu, 14 Jul 2016, Clem Cole wrote:
Could you be confusing the fact the true and false
were implemented by
external commands in some early shell's
And on the Mac and FreeBSD, they still are (as well as being builtins).
At one time they were shell scripts e.g. "exit 0" for "true".
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will
suffer."
10:47 p.m.
At one time they were shell scripts e.g. "exit 0" for "true".
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will
suffer."
Indeed. Here's what they look like in Solaris 8 .. /usr/bin/true is just
comments.
lod# cat /usr/bin/true
#!/usr/bin/sh
# Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T
# All Rights Reserved
# THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T
# The copyright notice above does not evidence any
# actual or intended publication of such source code.
#ident "(a)(#)true.sh 1.6 93/01/11 SMI" /* SVr4.0 1.4 */
lod# cat /usr/bin/false
#!/usr/bin/sh
# Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T
# All Rights Reserved
# THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T
# The copyright notice above does not evidence any
# actual or intended publication of such source code.
#ident "(a)(#)false.sh 1.6 93/01/11 SMI" /* SVr4.0 1.3 */
exit 255
lod# uname -a
SunOS lod 5.8 Generic_108528-05 sun4u sparc SUNW,UltraAX-i2
lod#
--corey
10:49 p.m.
On 2016-Jul-15 08:36:56 +1000, Dave Horsfall <dave(a)horsfall.org> wrote:
On Thu, 14 Jul 2016, Clem Cole wrote:
> Could you be confusing the fact the true and false were implemented by
> external commands in some early shell's
I was always amused by AT&T adding a multi-kB copyright notice to what
had previously been an empty file.
And on the Mac and FreeBSD, they still are (as well as
being builtins).
FreeBSD provides a convenient list of what commands are (currently) builtin
to the provided shells and available externally:
https://www.freebsd.org/cgi/man.cgi?builtin
--
Peter Jeremy
11:27 p.m.
Thought I'd mention here that the OP was asking about the original shell,
and that the Mashey and Bourne shells were much newer than that.
On Thu, Jul 14, 2016 at 4:49 PM, Peter Jeremy <peter(a)rulingia.com> wrote:
On 2016-Jul-15 08:36:56 +1000, Dave Horsfall
<dave(a)horsfall.org> wrote:
On Thu, 14 Jul 2016, Clem Cole wrote:
> Could you be confusing the fact the true and false were implemented by
> external commands in some early shell's
I was always amused by AT&T adding a multi-kB copyright notice to what
had previously been an empty file.
And on the Mac and FreeBSD, they still are (as
well as being builtins).
FreeBSD provides a convenient list of what commands are (currently) builtin
to the provided shells and available externally:
https://www.freebsd.org/cgi/man.cgi?builtin
--
Peter Jeremy
15 Jul
15 Jul
10:13 a.m.
Marc Rochkind <rochkind(a)basepath.com> wrote:
Thought I'd mention here that the OP was asking
about the original shell,
and that the Mashey and Bourne shells were much newer than that.
BTW: last Year there was a talk from Stephen Bourne af BSDcon where he
explained how the Bourne Shell started. It seems that Mashey, Bourne and csh
all started with the Thompson Shell code.
...and from a todays view, the time between 1970 anf 1976 is a short time
compared to the fact that the Bourne Shell now exists since 40 years.
Jörg
--
EMail:joerg@schily.net (home) Jörg Schilling D-13353 Berlin
joerg.schilling(a)fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.org/private/
http://sourceforge.net/projects/schilytools/files/'
14 Jul
14 Jul
11:10 p.m.
On Jul 14, 2016, at 6:36 PM, Dave Horsfall
<dave(a)horsfall.org> wrote:
On Thu, 14 Jul 2016, Clem Cole wrote:
Actually, one of the UNIX releases had NO EXECUTABLE CODE in /bin/true. The default is
to return the true.
There was 20 lines of copyright/rights notice in commends.
Could you be confusing the fact the true and
false were implemented by
external commands in some early shell's
And on the Mac and FreeBSD, they still are (as well as being builtins).
At one time they were shell scripts e.g. "exit 0" for "true". 
15 Jul
15 Jul
1:41 a.m.
On 14 July 2016 at 19:10, Ronald Natalie <ron(a)ronnatalie.com> wrote:
[...]
Actually, one of the UNIX releases had NO EXECUTABLE
CODE in /bin/true. The default is to return the true.
There was 20 lines of copyright/rights notice in commends.
https://www.computer.org/csdl/mags/so/2015/02/mso2015020010.pdf
9 a.m.
Dave Horsfall <dave(a)horsfall.org> wrote:
On Thu, 14 Jul 2016, Clem Cole wrote:
This isn't a BSDism: POSIX requires that most built-in commands also exist
as executables on the PATH. The exceptions are the "special built-in
commands" which manipulate the shell command language state, e.g. break
and set.
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#ta…
Tony.
--
f.anthony.n.finch <dot(a)dotat.at> http://dotat.at/ - I xn--zr8h punycode
Humber, Thames, Dover: West or southwest 4 or 5, increasing 6 at times. Slight
or moderate. Mainly fair. Good.
Could you be confusing the fact the true and
false were implemented by
external commands in some early shell's
And on the Mac and FreeBSD, they still are (as well as being builtins).
At one time they were shell scripts e.g. "exit 0" for "true". 
14 Jul
14 Jul
2:11 p.m.
On Thu, 14 Jul 2016 16:18:43 +0300, Diomidis Spinellis wrote
I remember hearing that originally the Unix shell had
control structures
(e.g. if, while, case) implemented through external commands. However,
I can't see this reflected in the source code. The 7th Edition
Bourne shell has these commands built-in (usr/src/cmd/sh/cmd.c), while
the 6th Edition (usr/source/s2/sh.c) seems to lack them completely.
http://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s1/if.c
http://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s1/goto.c
--
Kevin Schoedel <schoedel(a)kw.igs.net> VA3TCS
2:38 p.m.
On 14/07/2016 17:11, schoedel(a)kw.igs.net wrote:
On Thu, 14 Jul 2016 16:18:43 +0300, Diomidis Spinellis
wrote
Thank you! So:
- if(1) gets as arguments an expression to evaluate and the command to
execute if the expression is true, and
- goto(1) changes the seek offset of the shared standard input file
descriptor to match the label's position in the file.
This is a much simpler implementation that what I thought would be the
case, but, true to the spirit of Unix, remarkably effective.
I remember hearing that originally the Unix shell
had control structures
(e.g. if, while, case) implemented through external commands. However,
I can't see this reflected in the source code. The 7th Edition
Bourne shell has these commands built-in (usr/src/cmd/sh/cmd.c), while
the 6th Edition (usr/source/s2/sh.c) seems to lack them completely.
http://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s1/if.c
http://www.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s1/goto.c 
3:46 p.m.
Diomidis Spinellis scripsit:
The 7th Edition Bourne shell has these commands
built-in
(usr/src/cmd/sh/cmd.c), while the 6th Edition (usr/source/s2/sh.c)
seems to lack them completely.
Between the 6e shell and the Bourne shell there was the Mashey, or PWB,
shell, which was the first to have them built in. So if they existed,
they were probably separate commands on 6e-ish systems that didn't reach
the outside world. It's important to remember that the whole terminology
of editions and releases didn't apply within Bell Labs itself.
--
John Cowan http://www.ccil.org/~cowan cowan(a)ccil.org
"The serene chaos that is Courage, and the phenomenon of Unopened
Consciousness have been known to the Great World eons longer than Extaboulism."
"Why is that?" the woman inquired.
"Because I just made that word up", the Master said wisely.
--Kehlog Albran, The Profit
4:30 p.m.
On Thu, Jul 14, 2016, at 11:46, John Cowan wrote:
Between the 6e shell and the Bourne shell there was
the Mashey, or PWB,
shell, which was the first to have them built in. So if they existed,
they were probably separate commands on 6e-ish systems that didn't reach
the outside world. It's important to remember that the whole terminology
of editions and releases didn't apply within Bell Labs itself.
They're present in 6e, they're just not in the shell source code because
they don't require any special support from the shell.
2849
days inactive
2850
days old
15 comments
14 participants
participants (14)
-
Clem Cole -
corey＠lod.com -
Dave Horsfall -
Diomidis Spinellis -
John Cowan -
Marc Rochkind -
Mary Ann Horton -
Nemo -
Peter Jeremy -
Random832 -
Ronald Natalie -
schily＠schily.net -
schoedel＠kw.igs.net -
Tony Finch