In article <slrnuq546h.20hn.naddy@lorvorc.mips.inka.de>,
Christian Weisgerber <naddy@mips.inka.de> wrote:

On 2024-01-13, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

Is there a possibility to somehow get readline(3) editing support
into such a read loop, so that whenever the prompt is displayed I
can skim (e.g. with cursor keys) through the previous data input?

If not in ksh; is that maybe possible in bash or zsh ?

Not in bash, where "read -e" will use readline(3), but it doesn't
keep any history, so you can't access previous input.

No idea what you're on about here. It works as expected for me.

--
"The party of Lincoln has become the party of John Wilkes Booth."

- Carlos Alazraqui -

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On Sat, 13 Jan 2024 14:52:56 +0000, Kenny McCormack wrote:

In article <slrnuq546h.20hn.naddy@lorvorc.mips.inka.de>,
Christian Weisgerber <naddy@mips.inka.de> wrote:

On 2024-01-13, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

Is there a possibility to somehow get readline(3) editing support
into such a read loop, so that whenever the prompt is displayed I
can skim (e.g. with cursor keys) through the previous data input?

If not in ksh; is that maybe possible in bash or zsh ?

Not in bash, where "read -e" will use readline(3), but it doesn't
keep any history, so you can't access previous input.

No idea what you're on about here. It works as expected for me.

I've never used this bash feature myself, so I don't have any firsthand knowledge of it.

HOWEVER, it appears that bash(1) uses certain user-configurable
settings[1] to enable or disable the "history" options of bash(1)'s
"read -e"

P'haps Christian does not have these options enabled (thus causing
"read -e" to ignore line history), and you /do/ have them enabled
(either by choice, or by default).

[1] See bash(1) "READLINE" section, specifically the "Readline
Variables" subsection, and the "Readline Initialization" subsection
for information on how to enable/disable history.
--
Lew Pitcher
"In Skills We Trust"

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On 2024-01-13, Kenny McCormack <gazelle@shell.xmission.com> wrote:

Not in bash, where "read -e" will use readline(3), but it doesn't
keep any history, so you can't access previous input.

No idea what you're on about here.

What I said.

Anybody can try it for themselves:

while IFS= read -r -e -p "prompt> " line
do
echo "[$line]"
done

Actually, the lack of history is only true if you run it in a script.
In an interactive shell, there is history--but it's the command
history and it does not include the "read" input.

Bash 5.2.21.
--
Christian "naddy" Weisgerber naddy@mips.inka.de

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On 13.01.2024 16:48, Christian Weisgerber wrote:

On 2024-01-13, Kenny McCormack <gazelle@shell.xmission.com> wrote:

Not in bash, where "read -e" will use readline(3), but it doesn't
keep any history, so you can't access previous input.

No idea what you're on about here.

What I said.

Anybody can try it for themselves:

while IFS= read -r -e -p "prompt> " line
do
echo "[$line]"
done

Actually, the lack of history is only true if you run it in a script.
In an interactive shell, there is history--but it's the command
history and it does not include the "read" input.

That would be okay (at least for ksh) since ksh's 'read -s' allows to
drop the read input to the command history. (But ksh doesn't have the
'read -e', OTOH. I thought the requirement would not be uncommon and
some [emphasis!] _easy_ support would be in the shells, but no, it's
cursed.)

Janis, continuing later...

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On 2024-01-14, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

That would be okay (at least for ksh) since ksh's 'read -s' allows to
drop the read input to the command history.

Bash also has a way to push commands into history. And in an
_interactive_ shell, "read -e" has access to history. Also, it
looks like the loop is considered a single command. We can combine
all this:

#!/usr/local/bin/bash -i
while IFS= read -r -e -p "prompt> " line
do
echo "[$line]"
history -s "$line"
done

It seems fragile, though, depending on underspecified behavior.
And I lack an understanding of the consequences of forcing a shell
to run as if interactive when executing a script.

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

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In article <slrnuq7qmg.2tbp.naddy@lorvorc.mips.inka.de>,
Christian Weisgerber <naddy@mips.inka.de> wrote:
...

#!/usr/local/bin/bash -i
while IFS= read -r -e -p "prompt> " line
do
echo "[$line]"
history -s "$line"
done

Wow. I just tried adding "-i" to my script (see other thread) - and it
works - or does it?

If you add -i, you get history, but the history is the script itself, not things you've previously entered at the prompt. So, that's no good.

--
The difference between communism and capitalism?
In capitalism, man exploits man. In communism, it's the other way around.

- Daniel Bell, The End of Ideology (1960) -

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On 2024-01-14, Christian Weisgerber <naddy@mips.inka.de> wrote:

On 2024-01-14, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

That would be okay (at least for ksh) since ksh's 'read -s' allows to
drop the read input to the command history.

Bash also has a way to push commands into history. And in an
_interactive_ shell, "read -e" has access to history. Also, it
looks like the loop is considered a single command. We can combine
all this:

#!/usr/local/bin/bash -i
while IFS= read -r -e -p "prompt> " line
do
echo "[$line]"
history -s "$line"
done

It seems fragile, though, depending on underspecified behavior.
And I lack an understanding of the consequences of forcing a shell
to run as if interactive when executing a script.

This works for me. It's the stripped down version of a couple of scripts
I use every login session ...

#!/bin/bash

HISTFILE=$HOME/.history.test
HISTNUM=200

while $loop ; do
echo
set -H -o history
history -r
read -p "prompt : " -e ans
echo "$ans" >> $HISTFILE
case "$ans" in
q|quit|Q|Quit|QUIT)
exit 0
;;
esac
done


HTH
Jim

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On 14.01.2024 19:13, Jim Jackson wrote:

This works for me. It's the stripped down version of a couple of scripts
I use every login session ...

It indeed looks good; I can retrieve the history entries with the arrow
up/down keys, then navigate with the arrow left/right keys (and also
with the Vi keys), I can even issue Vi commands, etc. - Nice. - Thanks.

Janis

#!/bin/bash

HISTFILE=$HOME/.history.test
HISTNUM=200

while $loop ; do
echo
set -H -o history
history -r
read -p "prompt : " -e ans
echo "$ans" >> $HISTFILE
case "$ans" in
q|quit|Q|Quit|QUIT)
exit 0
;;
esac
done

HTH
Jim

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On 2024-01-14, Jim Jackson <jj@franjam.org.uk> wrote:

This works for me. It's the stripped down version of a couple of scripts
I use every login session ...

#!/bin/bash

HISTFILE=$HOME/.history.test
HISTNUM=200

while $loop ; do
echo
set -H -o history

Oh! That's better. We can enable history in a non-interactive
shell and push input lines into the history:

#!/usr/local/bin/bash
set -o history
while IFS= read -r -e -p "prompt> " line
do
echo "[$line]"
history -s "$line"
done

That's the bash solution to Janis's original problem.

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

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