On 2022-08-05, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
> scott@slp53.sl.home (Scott Lurndal) writes:
>> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>>>scott@slp53.sl.home (Scott Lurndal) writes:
>>>> muttley@dastardlyhq.com writes:
>>>>>On Thu, 04 Aug 2022 20:28:06 GMT
>>>>>scott@slp53.sl.home (Scott Lurndal) wrote:
>>>[...]
>>>>>>If there's no she-bang, then the script can still be run by
>>>>>>explicitly invoking the appropriate shell (bash /path/to/bash/script).
>>>>>
>>>>>It'll be invoked directly anyway by /bin/sh if its +x. I'd have thought in
>>>>>you three plus decades of experience would have discovered that by now.
>>>>
>>>> Yes, that experience tells me that don't want to rely on that behavior,
>>>> because it doesn't necessarily invoke /bin/sh, it invokes $SHELL.
>>>> And if the shell script being invoked isn't in $SHELL dialect, undefined
>>>> behavior will ensue.
>>>>
>>>> That's why we always either use she-bang, or use the invoke the script
>>>> using the target shell explicitly.
>>>
>>>In a quick experiment, it seems that such a script is invoked either by
>>>current shell or by /bin/sh, depending on which shell I invoke it from.
>>>I don't see any cases where it depends on $SHELL.
>>>
>>>The behavior may vary on different systems -- which is why I also avoid
>>>relying on it.
>>
>> Open Group says this (under execle):
>>
>> There are two distinct ways in which the contents of the process image
>> file may cause the execution to fail, distinguished by the setting of
>> errno to either [ENOEXEC] or [EINVAL] (see the ERRORS section). In the
>> cases where the other members of the exec family of functions would fail
>> and set errno to [ENOEXEC], the execlp() and execvp() functions shall
>> execute a command interpreter and the environment of the executed command
>> shall be as if the process invoked the sh utility using execl() as follows:
>>
>> execl(<shell path>, arg0, file, arg1, ..., (char *)0);
>>
>> where <shell path> is an unspecified pathname for the sh utility, file
>> is the process image file, and for execvp(), where arg0, arg1, and
>> so on correspond to the values passed to execvp() in argv[0], argv[1], and so on.
>>
>> I've worked with C library implementations that derive <shell path> from $SHELL
>> if set.
>
> And for at least some shells, executing a file doesn't just invoke one
> of the exec*() functions. When I use execvp() in a C program to execute
> a script with no "#!" line, it uses /bin/sh. When I run the same script
> from bash, it uses the currently running bash, even when the current
> bash is neither $SHELL nor /bin/bash.

What? Only sourcing a script should use the current shell; sourcing
isn't execution.

By "run from bash" are you referring to passing the script as a command
line argument as in

bash ./script

?

That bash instance will of course read and run the script. But if you
give bash a command via standard input:

bash$ ./script

that must run it in a child process..

When I do this:

$ echo ./testscript | strace -o log bash

The strace log has:

read(0, ".", 1) = 1
read(0, "/", 1) = 1
read(0, "t", 1) = 1
read(0, "e", 1) = 1
read(0, "s", 1) = 1
read(0, "t", 1) = 1
read(0, "s", 1) = 1
read(0, "c", 1) = 1
read(0, "r", 1) = 1
read(0, "i", 1) = 1
read(0, "p", 1) = 1
read(0, "t", 1) = 1
read(0, "\n", 1) = 1
rt_sigprocmask(SIG_BLOCK, [INT CHLD], [], 8) = 0
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7f8aae8) = 1407
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=1407, si_uid=500, si_status=0, si_utime=0, si_stime=0} ---

Bash reads the command and spawns a process.

Moreover, if we trace this again with -f to see what the child is doing:

1670 execve("./testscript", ["./testscript"], 0x1e00500 /* 24 vars */) = -1 ENOEXEC (Exec format error)
1670 openat(AT_FDCWD, "./testscript", O_RDONLY|O_LARGEFILE) = 3
1670 read(3, "FOO=abc\ncd /\n", 128) = 13
1670 close(3) = 0

See: execve happens.

It cannot be that bash would read a command and just run it in the
current shell, if that command isn't a built-in or user-defined
function.

It also cannot be that bash would just fork a child process, and
then interpret the script without exec; a script without hash bang
has to be given the proper treatment through exec to choose
the interpreter in a consistent way.

--
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal

On Thu, 04 Aug 2022 17:06:33 -0400
Dan Espen <dan1espen@gmail.com> wrote:
>muttley@dastardlyhq.com writes:
>
>> On Thu, 04 Aug 2022 20:28:06 GMT
>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>muttley@dastardlyhq.com writes:
>>>>Should. How often do you see it in practice?
>>>>
>>>
>>>100%. As noted in other posts, we use a number of different interactive
>>>shells, and a number of scripting languages (tcsh, ksh, bash, perl, python,
>>>tcl, et alia). And that's been true for every POE I've worked in for
>>>the last three plus decades (system or processor OEMs primarily).
>>
>> Don't believe you. I've seen more scripts than I can count that didn't
>> have the hash bang at the start. No idea what a she-bang is. Sounds like
>> a service for sailors in a port.
>
>Well, where I worked, every shell script we shipped to customers had
>a hash bang. Feel free to not believe me too.

I wasn't talking about commercially shipped scripts, I was talking about
internal ones as I'm sure you understood.

On Thu, 04 Aug 2022 23:23:05 GMT
scott@slp53.sl.home (Scott Lurndal) wrote:
>That's why we always either use she-bang, or use the invoke the script

Wtf is "she" for? Its either called hash or pound depending on what side of
the atlantic you're on. Its never called "she" and I've never heard anyone
anywhere ever refer to it like this.

On 05.08.2022 15:07, Geoff Clare wrote:
> Ed Morton wrote:
>
>> On 8/4/2022 4:06 PM, Dan Espen wrote:
>>> muttley@dastardlyhq.com writes:
>>>
>>>> On Thu, 04 Aug 2022 20:28:06 GMT
>>>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>>> muttley@dastardlyhq.com writes:
>>>>>> Should. How often do you see it in practice?
>>>>>>
>>>>>
>>>>> 100%. As noted in other posts, we use a number of different interactive
>>>>> shells, and a number of scripting languages (tcsh, ksh, bash, perl, python,
>>>>> tcl, et alia). And that's been true for every POE I've worked in for
>>>>> the last three plus decades (system or processor OEMs primarily).
>>>>
>>>> Don't believe you. I've seen more scripts than I can count that didn't
>>>> have the hash bang at the start. No idea what a she-bang is. Sounds like
>>>> a service for sailors in a port.
>>>
>>> Well, where I worked, every shell script we shipped to customers had
>>> a hash bang. Feel free to not believe me too.
>>>
>>
>> Likewise, 100% of the shell scripts shipped to customers or used as a
>> tool has a shebang.
>
> Where I work 100% of (hundreds of) shell scripts shipped to customers
> do not have a #! line. That's because they are required to conform to
> POSIX, and POSIX says that if the first line starts with #! the results
> are unspecified.

In the past we rarely shipped _scripts_ to customers, rather mostly
large program systems or single binaries or complete runtime packages.
Anyway, an executable script has to be started with the appropriate
(well defined) interpreter, so an explicit shebang definition would
be the cleanest way, IMO. (Personally and privately I explicitly use
the interpreter on the script file in most cases.) But what we (or
our company) ships is beyond a generally valid statement. If I inspect
the PATH on my Linux system and the script files located there I find
round about 1000 scripts, all with a #! line and with the interpreters
depicted in the list

324 #!/bin/sh
152 #!/usr/bin/perl
132 #!/usr/bin/perl -w
92 #!/usr/bin/python
72 #! /bin/sh
56 #!/bin/bash
37 #! /usr/bin/perl
31 #!/bin/sh -e
24 #! /usr/bin/python
15 #! /usr/bin/env
13 #!/usr/bin/env python
11 #! /bin/bash
6 #!/bin/sh -
5 #!/usr/bin/ruby1.8
3 #!/bin/bash -e
3 #! /usr/bin/python2.7
2 #!/usr/bin/wish
2 #!/usr/bin/env ruby
1 #!/usr/bin/python2.7
1 #!/usr/bin/python -Es
1 #!/usr/bin/perl -wl
1 #!/usr/bin/perl --
1 #!/usr/bin/guile -s
1 #!/usr/bin/env perl
1 #!/usr/bin/env nickle
1 #!/usr/bin/env bash
1 #!/bin/sh -f
1 #!/bin/sh -eu
1 #!/bin/mksh
1 #! /usr/bin/python3

Janis

On 06.08.2022 10:36, Muttley@dastardlyhq.com wrote:
> On Thu, 04 Aug 2022 23:23:05 GMT
> scott@slp53.sl.home (Scott Lurndal) wrote:
>> That's why we always either use she-bang, or use the invoke the script
>
> Wtf is "she" for? Its either called hash or pound depending on what side of
> the atlantic you're on. Its never called "she" and I've never heard anyone
> anywhere ever refer to it like this.

You find hints here: https://www.in-ulm.de/~mascheck/various/shebang/

Janis

Muttley@dastardlyhq.com writes:
> scott@slp53.sl.home (Scott Lurndal) wrote:
>>That's why we always either use she-bang, or use the invoke the script
>
> Wtf is "she" for? Its either called hash or pound depending on what side of
> the atlantic you're on. Its never called "she" and I've never heard anyone
> anywhere ever refer to it like this.

People have been calling it that for ages. I’m not a fan but it’s not
new.

--
https://www.greenend.org.uk/rjk/

On 8/6/2022 3:36 AM, Muttley@dastardlyhq.com wrote:
> On Thu, 04 Aug 2022 23:23:05 GMT
> scott@slp53.sl.home (Scott Lurndal) wrote:
>> That's why we always either use she-bang, or use the invoke the script
>
> Wtf is "she" for? Its either called hash or pound depending on what side of
> the atlantic you're on. Its never called "she" and I've never heard anyone
> anywhere ever refer to it like this.
>
>

Not sure I've ever heard it called anything other than a shebang prior
to this discussion but anyway, I already provided you a reference for it
at https://en.wikipedia.org/wiki/Shebang_(Unix) and see also
https://unix.stackexchange.com/questions/149045/why-is-shebang-called-shebang
for suggestions that it's derived from either of these:

haSH BANG
SHarp BANG

given that # is sometimes referred to as a hash or sharp character and !
is sometimes referred to as a bang character.

Regards,

Ed.

Muttley@dastardlyhq.com writes:

> On Thu, 04 Aug 2022 17:06:33 -0400
> Dan Espen <dan1espen@gmail.com> wrote:
>>muttley@dastardlyhq.com writes:
>>
>>> On Thu, 04 Aug 2022 20:28:06 GMT
>>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>>muttley@dastardlyhq.com writes:
>>>>>Should. How often do you see it in practice?
>>>>>
>>>>
>>>>100%. As noted in other posts, we use a number of different interactive
>>>>shells, and a number of scripting languages (tcsh, ksh, bash, perl, python,
>>>>tcl, et alia). And that's been true for every POE I've worked in for
>>>>the last three plus decades (system or processor OEMs primarily).
>>>
>>> Don't believe you. I've seen more scripts than I can count that didn't
>>> have the hash bang at the start. No idea what a she-bang is. Sounds like
>>> a service for sailors in a port.
>>
>>Well, where I worked, every shell script we shipped to customers had
>>a hash bang. Feel free to not believe me too.
>
> I wasn't talking about commercially shipped scripts, I was talking about
> internal ones as I'm sure you understood.

No, no way was that even implied.

Not really interested in scripts thrown together by a novice.
For what it's worth all my home grown temporary use scripts have a hash
bang too.

--
Dan Espen

Muttley@dastardlyhq.com writes:

> On Thu, 04 Aug 2022 23:23:05 GMT
> scott@slp53.sl.home (Scott Lurndal) wrote:
>>That's why we always either use she-bang, or use the invoke the script
>
> Wtf is "she" for? Its either called hash or pound depending on what side of
> the atlantic you're on. Its never called "she" and I've never heard anyone
> anywhere ever refer to it like this.

Here, have a look:

https://en.wikipedia.org/wiki/Shebang_(Unix)

Someone seems to be batting 1000.

--
Dan Espen

In article <tclltg$3r6oa$2@dont-email.me>,
Dan Espen <dan1espen@gmail.com> wrote:
....
>Someone seems to be batting 1000.

Hint: It's not you.

--
Atheism:
It's like being the only sober person in the car, and nobody will let you drive.

gazelle@shell.xmission.com (Kenny McCormack) writes:

> In article <tclltg$3r6oa$2@dont-email.me>,
> Dan Espen <dan1espen@gmail.com> wrote:
> ...
>>Someone seems to be batting 1000.
>
> Hint: It's not you.

A nonsense comment from Kenny.
Another normal day.

Ask yourself, what is he batting 1000 at?
Why would I want to be doing the same?

--
Dan Espen

On Sat, 06 Aug 2022 12:30:52 +0100
Richard Kettlewell <invalid@invalid.invalid> wrote:
>Muttley@dastardlyhq.com writes:
>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>That's why we always either use she-bang, or use the invoke the script
>>
>> Wtf is "she" for? Its either called hash or pound depending on what side of
>> the atlantic you're on. Its never called "she" and I've never heard anyone
>> anywhere ever refer to it like this.
>
>People have been calling it that for ages. I’m not a fan but it’s not
>new.

I've never heard it called that and I've been using *nix for 30 years. Perhaps
its an american thing.

On Sat, 06 Aug 2022 08:13:34 -0400
Dan Espen <dan1espen@gmail.com> wrote:
>Muttley@dastardlyhq.com writes:
>
>> On Thu, 04 Aug 2022 23:23:05 GMT
>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>That's why we always either use she-bang, or use the invoke the script
>>
>> Wtf is "she" for? Its either called hash or pound depending on what side of
>> the atlantic you're on. Its never called "she" and I've never heard anyone
>> anywhere ever refer to it like this.
>
>Here, have a look:
>
>https://en.wikipedia.org/wiki/Shebang_(Unix)

Doesn't explain why though I skim read it.

>Someone seems to be batting 1000.

Is that some obscure sports analogy?

Muttley@dastardlyhq.com writes:
>On Thu, 04 Aug 2022 23:23:05 GMT
>scott@slp53.sl.home (Scott Lurndal) wrote:
>>That's why we always either use she-bang, or use the invoke the script
>
>Wtf is "she" for? Its either called hash or pound depending on what side of
>the atlantic you're on.

It is also known as "sharp" by musicians.

On Sat, 06 Aug 2022 15:25:23 GMT
scott@slp53.sl.home (Scott Lurndal) wrote:
>Muttley@dastardlyhq.com writes:
>>On Thu, 04 Aug 2022 23:23:05 GMT
>>scott@slp53.sl.home (Scott Lurndal) wrote:
>>>That's why we always either use she-bang, or use the invoke the script
>>
>>Wtf is "she" for? Its either called hash or pound depending on what side of
>>the atlantic you're on.
>
>It is also known as "sharp" by musicians.

True. Also MS with C# :)

On Sat, 06 Aug 2022 07:30:52 -0400, Richard Kettlewell <invalid@invalid.invalid> wrote:

> Muttley@dastardlyhq.com writes:
>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>> That's why we always either use she-bang, or use the invoke the script
>>
>> Wtf is "she" for? Its either called hash or pound depending on what side of
>> the atlantic you're on. Its never called "she" and I've never heard anyone
>> anywhere ever refer to it like this.
>
> People have been calling it that for ages. I’m not a fan but it’s not
> new.

Regarding the # character, I was taught it was called a number sign.
https://en.wikipedia.org/wiki/Number_sign
kcharselect agrees, Character: # U+0023, Name: NUMBER SIGN
or a sharp in musical notation.

I didn't here the term hash sign used for it till I started using usenet.
As for calling it the pound sign, I assume that's because US layout keyboards
don't have a £ key.

Regards, Dave Hodgins

On 2022-08-06, Muttley@dastardlyhq.com <Muttley@dastardlyhq.com> wrote:

>>>>That's why we always either use she-bang, or use the invoke the script
>>>
>>> Wtf is "she" for? Its either called hash or pound depending on what side of
>>> the atlantic you're on. Its never called "she" and I've never heard anyone
>>> anywhere ever refer to it like this.
>>
>>People have been calling it that for ages. I’m not a fan but it’s not
>>new.
>
> I've never heard it called that and I've been using *nix for 30 years. Perhaps
> its an american thing.

The combination of #! at the start of a script has been called a
"shebang" for decades.

Nobody is calling a single # a "she".

--
Christian "naddy" Weisgerber naddy@mips.inka.de

On 2022-08-05, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
> John McCue <jmccue@neutron.hsd1.ma.comcast.net> writes:
>> Geoff Clare <geoff@clare.see-my-signature.invalid> wrote:
>> <snip>
>>>
>>> Where I work 100% of (hundreds of) shell scripts shipped to customers
>>> do not have a #! line. That's because they are required to conform to
>>> POSIX, and POSIX says that if the first line starts with #! the results
>>> are unspecified.
>>
>> I never read POSIX, but '#!' statement is very odd. I do
>> not doubt POSIX says that since I think it was first done
>> many decades ago by a US Gov committee.
>
> IEEE, not the US Government.
>
>> That statement would make my head spin, as you know, a '#'
>> is a comment in all the shells I am aware of.
>> The phrase "good enough for Gov Work" comes to mind :)
>
> Yes, # introduces a comment in most shells.
>
> I haven't found that statement in POSIX about #!, but I presume the
> reason is that saying it's unspecified allows the usual implementation
> while not requiring POSIX to specify the behavior.

The usual implementation processes #! like a comment, since the
hash bang mechanism is designed to be invisible to an interpreter
which uses # comments, imposing no requirements on it.

Therefore, the only good reason the spec would be bringing in
unspecified behavior in the treatment of a certain shape of comment in a
certain place in the file would be to allow UNusual implementations of
hash bang, where the interpreter has some responsibility in parsing the
hash bang line and possibly deferring to a different interpreter.

One reason why an interpreter would look at the hash bang line specially
would be to parse multiple command line arguments out of it in an
implementation where only one argument is allowed.

#!/path/to/interp --multiple --args --here

Here interp, before processing any other arguments, could open the
script, see the #! and then edit its argument list from that
information.

The POSIX wording has the effect of allowing the above tricks.

Muttley@dastardlyhq.com writes:
>On Sat, 06 Aug 2022 15:25:23 GMT
>scott@slp53.sl.home (Scott Lurndal) wrote:
>>Muttley@dastardlyhq.com writes:
>>>On Thu, 04 Aug 2022 23:23:05 GMT
>>>scott@slp53.sl.home (Scott Lurndal) wrote:
>>>>That's why we always either use she-bang, or use the invoke the script
>>>
>>>Wtf is "she" for? Its either called hash or pound depending on what side of
>>>the atlantic you're on.
>>
>>It is also known as "sharp" by musicians.
>
>True. Also MS with C# :)

Which is the source for _SH_e bang.

"David W. Hodgins" <dwhodgins@nomail.afraid.org> writes:
>On Sat, 06 Aug 2022 07:30:52 -0400, Richard Kettlewell <invalid@invalid.invalid> wrote:
>
>> Muttley@dastardlyhq.com writes:
>>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>> That's why we always either use she-bang, or use the invoke the script
>>>
>>> Wtf is "she" for? Its either called hash or pound depending on what side of
>>> the atlantic you're on. Its never called "she" and I've never heard anyone
>>> anywhere ever refer to it like this.
>>
>> People have been calling it that for ages. I’m not a fan but it’s not
>> new.
>
>Regarding the # character, I was taught it was called a number sign.
>https://en.wikipedia.org/wiki/Number_sign
>kcharselect agrees, Character: # U+0023, Name: NUMBER SIGN
>or a sharp in musical notation.
>
>I didn't here the term hash sign used for it till I started using usenet.
>As for calling it the pound sign, I assume that's because US layout keyboards
>don't have a £ key.

In the US, long before computers, the octothorpe was used as
shorthand for one pound in weight. e.g. 100# == cw.

Kaz Kylheku <480-992-1380@kylheku.com> writes:
> On 2022-08-05, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>>>>scott@slp53.sl.home (Scott Lurndal) writes:
>>>>> muttley@dastardlyhq.com writes:
>>>>>>On Thu, 04 Aug 2022 20:28:06 GMT
>>>>>>scott@slp53.sl.home (Scott Lurndal) wrote:
>>>>[...]
>>>>>>>If there's no she-bang, then the script can still be run by
>>>>>>>explicitly invoking the appropriate shell (bash /path/to/bash/script).
>>>>>>
>>>>>>It'll be invoked directly anyway by /bin/sh if its +x. I'd have thought in
>>>>>>you three plus decades of experience would have discovered that by now.
>>>>>
>>>>> Yes, that experience tells me that don't want to rely on that behavior,
>>>>> because it doesn't necessarily invoke /bin/sh, it invokes $SHELL.
>>>>> And if the shell script being invoked isn't in $SHELL dialect, undefined
>>>>> behavior will ensue.
>>>>>
>>>>> That's why we always either use she-bang, or use the invoke the script
>>>>> using the target shell explicitly.
>>>>
>>>>In a quick experiment, it seems that such a script is invoked either by
>>>>current shell or by /bin/sh, depending on which shell I invoke it from.
>>>>I don't see any cases where it depends on $SHELL.
>>>>
>>>>The behavior may vary on different systems -- which is why I also avoid
>>>>relying on it.
>>>
>>> Open Group says this (under execle):
>>>
>>> There are two distinct ways in which the contents of the process image
>>> file may cause the execution to fail, distinguished by the setting of
>>> errno to either [ENOEXEC] or [EINVAL] (see the ERRORS section). In the
>>> cases where the other members of the exec family of functions would fail
>>> and set errno to [ENOEXEC], the execlp() and execvp() functions shall
>>> execute a command interpreter and the environment of the executed command
>>> shall be as if the process invoked the sh utility using execl() as follows:
>>>
>>> execl(<shell path>, arg0, file, arg1, ..., (char *)0);
>>>
>>> where <shell path> is an unspecified pathname for the sh utility, file
>>> is the process image file, and for execvp(), where arg0, arg1, and
>>> so on correspond to the values passed to execvp() in argv[0], argv[1], and so on.
>>>
>>> I've worked with C library implementations that derive <shell path> from $SHELL
>>> if set.
>>
>> And for at least some shells, executing a file doesn't just invoke one
>> of the exec*() functions. When I use execvp() in a C program to execute
>> a script with no "#!" line, it uses /bin/sh. When I run the same script
>> from bash, it uses the currently running bash, even when the current
>> bash is neither $SHELL nor /bin/bash.
>
> What? Only sourcing a script should use the current shell; sourcing
> isn't execution.
>
> By "run from bash" are you referring to passing the script as a command
> line argument as in
>
> bash ./script
>
> ?

No, I mean "./script".

> That bash instance will of course read and run the script. But if you
> give bash a command via standard input:
>
> bash$ ./script
>
> that must run it in a child process..

Yes. The question is how it runs it.

When I said it uses the current shell, I meant that it invokes it using
the current shell's executable, not that it runs it under the current
shell process. I see now that I was unclear about that.

> When I do this:
>
> $ echo ./testscript | strace -o log bash
>
> The strace log has:
>
[snip]
>
> Bash reads the command and spawns a process.
>
> Moreover, if we trace this again with -f to see what the child is doing:
>
> 1670 execve("./testscript", ["./testscript"], 0x1e00500 /* 24 vars */) = -1 ENOEXEC (Exec format error)
> 1670 openat(AT_FDCWD, "./testscript", O_RDONLY|O_LARGEFILE) = 3
> 1670 read(3, "FOO=abc\ncd /\n", 128) = 13
> 1670 close(3) = 0
>
> See: execve happens.
>
> It cannot be that bash would read a command and just run it in the
> current shell, if that command isn't a built-in or user-defined
> function.

Agreed.

> It also cannot be that bash would just fork a child process, and
> then interpret the script without exec; a script without hash bang
> has to be given the proper treatment through exec to choose
> the interpreter in a consistent way.

That doesn't seem to be the case.

Given a script "foo" with no "#!", running "./foo" from a shell prompt
will either invoke /bin/sh with the script name as an argument, or
invoke the executable for the currently running shell with the script
name as an argument, depending on the shell. My experiment indicates
that bash and ksh use themselves, while zsh and dash use sh.

A demonstration on Ubuntu 20.04.04 LTS (note that my default bash is a
newer version than /bin/bash):
========================================
$ echo $BASH_VERSION
5.1.0(1)-release
$ cat foo
# No shebang

if [ "$BASH_VERSION" ] ; then echo "This is bash $BASH_VERSION"
elif [ "$KSH_VERSION" ] ; then echo "This is ksh $KSH_VERSION"
elif [ "$ZSH_VERSION" ] ; then echo "This is zsh $ZSH_VERSION"
else echo "Unknown shell"
fi
ps -f -p $$
$ ./foo
This is bash 5.1.0(1)-release
UID PID PPID C STIME TTY TIME CMD
kst 1930385 1930335 0 13:59 pts/2 00:00:00 bash -l
$ bash -c ./foo
This is bash 5.1.0(1)-release
UID PID PPID C STIME TTY TIME CMD
kst 1930417 1930335 0 14:00 pts/2 00:00:00 bash -c ./foo
$ ksh -c ./foo
This is ksh Version AJM 93u+ 2012-08-01
UID PID PPID C STIME TTY TIME CMD
kst 1930466 1930335 0 14:00 pts/2 00:00:00 ./foo ./foo
$ zsh -c ./foo
Unknown shell
UID PID PPID C STIME TTY TIME CMD
kst 1930470 1930335 0 14:00 pts/2 00:00:00 sh ./foo
$ dash -c ./foo
Unknown shell
UID PID PPID C STIME TTY TIME CMD
kst 1930513 1930512 0 14:00 pts/2 00:00:00 /bin/sh ./foo
$ ========================================

(I never write scripts without a #! line, so I hadn't noticed this
behavior until recently.)

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */

"David W. Hodgins" <dwhodgins@nomail.afraid.org> writes:
> On Sat, 06 Aug 2022 07:30:52 -0400, Richard Kettlewell <invalid@invalid.invalid> wrote:
>
>> Muttley@dastardlyhq.com writes:
>>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>> That's why we always either use she-bang, or use the invoke the script
>>>
>>> Wtf is "she" for? Its either called hash or pound depending on what side of
>>> the atlantic you're on. Its never called "she" and I've never heard anyone
>>> anywhere ever refer to it like this.
>>
>> People have been calling it that for ages. I’m not a fan but it’s not
>> new.
>
> Regarding the # character, I was taught it was called a number sign.
> https://en.wikipedia.org/wiki/Number_sign
> kcharselect agrees, Character: # U+0023, Name: NUMBER SIGN
> or a sharp in musical notation.
>
> I didn't here the term hash sign used for it till I started using usenet.
> As for calling it the pound sign, I assume that's because US layout keyboards
> don't have a £ key.

And the '#' symbol is sometimes used to mean pound (weight).

Unicode calls it "NUMBER SIGN". Other names for it are pound sign,
hash, hashtag (in social media), sharp, and octothorp.

https://en.wikipedia.org/wiki/Number_sign

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */

Dropping de.comp.os.unix.shell and comp.unix.programmer.
Let's stop inundating a German newsgroup with posts in English.

Muttley@dastardlyhq.com writes:
> On Thu, 04 Aug 2022 23:23:05 GMT
> scott@slp53.sl.home (Scott Lurndal) wrote:
>>That's why we always either use she-bang, or use the invoke the script
>
> Wtf is "she" for? Its either called hash or pound depending on what side of
> the atlantic you're on. Its never called "she" and I've never heard anyone
> anywhere ever refer to it like this.

I've never heard the # character called "she", but the #! is very
commonly called a "shebang". The "sh" probably comes from either "haSH"
or "SHell". "Shebang" is an existing word in other contexts, as in "the
whole shebang"; that undoubtedly inspired the choice of abbreviation.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */

Muttley@dastardlyhq.com writes:

> On Sat, 06 Aug 2022 08:13:34 -0400
> Dan Espen <dan1espen@gmail.com> wrote:
>>Muttley@dastardlyhq.com writes:
>>Someone seems to be batting 1000.
>
> Is that some obscure sports analogy?

Not obscure. Easily accessed by doing a search.

--
Dan Espen

On Sat, 06 Aug 2022 17:11:32 -0400, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:

> "David W. Hodgins" <dwhodgins@nomail.afraid.org> writes:
>> On Sat, 06 Aug 2022 07:30:52 -0400, Richard Kettlewell <invalid@invalid.invalid> wrote:
>>
>>> Muttley@dastardlyhq.com writes:
>>>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>>>> That's why we always either use she-bang, or use the invoke the script
>>>>
>>>> Wtf is "she" for? Its either called hash or pound depending on what side of
>>>> the atlantic you're on. Its never called "she" and I've never heard anyone
>>>> anywhere ever refer to it like this.
>>>
>>> People have been calling it that for ages. I’m not a fan but it’s not
>>> new.
>>
>> Regarding the # character, I was taught it was called a number sign.
>> https://en.wikipedia.org/wiki/Number_sign
>> kcharselect agrees, Character: # U+0023, Name: NUMBER SIGN
>> or a sharp in musical notation.
>>
>> I didn't here the term hash sign used for it till I started using usenet.
>> As for calling it the pound sign, I assume that's because US layout keyboards
>> don't have a £ key.
>
> And the '#' symbol is sometimes used to mean pound (weight).
>
> Unicode calls it "NUMBER SIGN". Other names for it are pound sign,
> hash, hashtag (in social media), sharp, and octothorp.
>
> https://en.wikipedia.org/wiki/Number_sign

Also, I was taught the ! is called an exclamation mark, not a bang.

I read #! as number sign, exclamation mark.

Regards, Dave Hodgins