Hello the guy from https://luxferre.top and gopher://hoi.st
has pretty interesting stuff, such as

git://git.luxferre.top/awk-gold-collection.git

(Run
git clone --recursive git://git.luxferre.top/awk-gold-collection.git
to get them all)

The issue is 'subleq.awk' uses read from GNU Bash I'd guess; thus,
is not portable to sh/ksh. The flags are missing:

function getchar(c, cmd) { # POSIX-compatible getchar emulation with sh read
(cmd="c='';IFS= read -r -n 1 -d $'\\0' c;printf '%u' \"'$c\"") | getline c
close(cmd)
return int(c)
}

There's another one implemented at tgl.awk, some 'universal' library
with mission functions for POSIX awk's. Not so universal,
as it falls in the same traps: it depends on 'od' from
GNU coreutils, with flags equallly missing:

function getchar(c) {
if(!TGL_GCH_CMD) TGL_GCH_CMD = "od -tu1 -w1 -N1 -An -v" # first time usage
TGL_GCH_CMD | getline c
close(TGL_GCH_CMD)
return int(c)
}


Then I tried to it under C, both with a leading space and a
newline and with just the char:

int main()
{
int c;
if ((c = getchar()) != EOF) {
printf(" %d\n", c);
/* printf("%d", c); */
}
}

Then I edited both commands to be piped into getline to use
my custom C program, but I had no luck.
Subleq programs with no input work fine.
Once I try a Forth implemented in subleq, no input
is parsed right, as Forth doesn't eval a simple
"2 2 + .s" instruction.

subleq.fth and forth:

https://github.com/howerj/subleq/

The one in C works fine:

./subleq sublec.dec sublec.fth

2 3 + .s
5 ok

Not the case with awk (OpenBSD, one true awk), mawk and gawk:

awk -f subleq.awk ./subleq/subleq.dec ./sublec.fth

sublec.fth has extra Forth words, thus it can be slower to
parse under subleq.awk. But the core subleq.dec has a
minimal implementation enough to do basic arithmetic.
It works under the C implementation of subleq, again,
but not under subleq.awk (outside GNU oses).

Could it be possible to implement a true portable getchar?

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On 25.03.2025 10:51, anthk wrote:

Hello the guy from https://luxferre.top and gopher://hoi.st
has pretty interesting stuff, such as

[ shell specific or other tries to emulate some getchar function ]

Could it be possible to implement a true portable getchar?

Those who think that getchar is a useful function may implement that
natively in Awk. (It avoids external dependencies and all the issues
that the posted/quoted code has made obvious.)

Janis

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On 3/25/25 7:10 AM, Janis Papanagnou wrote:

On 25.03.2025 10:51, anthk wrote:

Hello the guy from https://luxferre.top and gopher://hoi.st
has pretty interesting stuff, such as

[ shell specific or other tries to emulate some getchar function ]

Could it be possible to implement a true portable getchar?

Those who think that getchar is a useful function may implement that
natively in Awk. (It avoids external dependencies and all the issues
that the posted/quoted code has made obvious.)

I know you can iterate over input strings a character at a time in AWK
but I don't think you can read a single character from stdin without
also providing a newline via ENTER, which is perhaps what the OP was
actually wanting to do?

I kind of like making CLI interactive stuff and like not having to
press ENTER after entering single character menu choices. Tried a
few options using bash and lua before landing on stty(1) and dd(1),
both POSIX tools:

--
# getchar_posix.awk - read exactly one char from stdin and return it
# without waiting for ENTER to be pressed.
#

BEGIN {
printf "enter a char: "
Char = getchar()
printf "\n you entered: %s\n", Char
}

function getchar( ,Cmd, Chr) {
# put TTY in "raw" mode..
system ("stty -icanon")
#
# read Chr via dd(1)..
Cmd = "dd bs=1 count=1 2>/dev/null"
Cmd | getline Chr
close (Cmd)
#
# put TTY in "normal" mode..
system ("stty icanon")
#
return Chr
}
--

Saving the TTY state via 'stty -g' beforehand would probably be a good
addition so if things go sideways the TTY isn't a mess.

-A

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In article <vrvv30$spj$1@nnrp.usenet.blueworldhosting.com>,
Arti F. Idiot <addr@is.invalid> wrote:

On 3/25/25 7:10 AM, Janis Papanagnou wrote:

On 25.03.2025 10:51, anthk wrote:

Hello the guy from https://luxferre.top and gopher://hoi.st
has pretty interesting stuff, such as

[ shell specific or other tries to emulate some getchar function ]

Could it be possible to implement a true portable getchar?

Those who think that getchar is a useful function may implement that
natively in Awk. (It avoids external dependencies and all the issues
that the posted/quoted code has made obvious.)

I know you can iterate over input strings a character at a time in AWK
but I don't think you can read a single character from stdin without
also providing a newline via ENTER, which is perhaps what the OP was
actually wanting to do?

This works for me:

--- Cut Here ---
@load "call_any"
BEGIN {
system("stty raw -echo");
s = " "
n = call_any("iisi","read",0,s,1)
system("stty sane");
print "s =","|"s"|","n =",n
}
--- Cut Here ---

Note: I could probably change the system() calls to use call_any() as well.

It looks like tcgetattr(3) and tcsetattr(3) are the currently accepted ways
of doing this. I've used those calls in my C programs, so would have to
adapt that to work with call_any().

--
Liberals live in a fantasy world where (street) criminals are good people.

Conservatives live in a fantasy world where businessmen are good people.

--- SoupGate-Win32 v1.05
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In article <vs0258$ncqh$1@news.xmission.com>,
Kenny McCormack <gazelle@shell.xmission.com> wrote:
...
This also works for me:

--- Cut Here ---
BEGIN {
cmd = "exec bash -c 'while :;do read -rsn1 < /dev/tty;echo $REPLY;done'"
while (cmd |& getline)
print "Result:",$0
}
--- Cut Here ---

--
The randomly chosen signature file that would have appeared here is more than 4 lines long. As such, it violates one or more Usenet RFCs. In order to remain in compliance with said RFCs, the actual sig can be found at the following URL:
http://user.xmission.com/~gazelle/Sigs/Voltaire

--- SoupGate-Win32 v1.05
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On 26.03.2025 05:16, Arti F. Idiot wrote:

On 3/25/25 7:10 AM, Janis Papanagnou wrote:

On 25.03.2025 10:51, anthk wrote:

Hello the guy from https://luxferre.top and gopher://hoi.st
has pretty interesting stuff, such as

[ shell specific or other tries to emulate some getchar function ]

Could it be possible to implement a true portable getchar?

Those who think that getchar is a useful function may implement that
natively in Awk. (It avoids external dependencies and all the issues
that the posted/quoted code has made obvious.)

I know you can iterate over input strings a character at a time in AWK
but I don't think you can read a single character from stdin without
also providing a newline via ENTER, which is perhaps what the OP was
actually wanting to do?

I don't know. - When I read 'getchar' I associated a character oriented function like awk's 'getline'. That would mean not reading from stdin
with some I/O buffered return-terminated input but just processing the
data as Awk would read its input from stdin or using 'getline' would.
You need to maintain some state, though; here the actual read in line
which acts like a buffer in buffered OS reads.

What I associated was actually something like

function getchar ()
{
if (_pos >= _len) {
do {
if ((getline _line) <=0)
return ""
}
while (!(_len = length (_line)))
_pos = 0
}
return substr (_line, ++_pos, 1)
}

used in contexts like

BEGIN {
# RS = "$^"
while (c = getchar())
print ">" c "<"
}

where the commented RS assignment could be activated in case you wanted
to also read the newline characters, or, without it, to just read in
the payload data of a line (or record). The necessary state information
is stored in those variables that are named with a leading underscore.

As said it's native Awk code without those dependencies on OS, on tools,
or on specific non-standard flags of tools.

(But as indicated in my previous response, I don't have any need for a
function like that. Maybe others do, don't know.)

Janis

[...]

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