What are you working on?

What are you working on? - Programming On Unix

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	freem Offline \| 17-08-2020, 01:24 PM \| #302

A dialog alternative.
It's a project I have since... long. I got some PoCs, now I'm working on the tooling I need.

My idea is to write a declarative DSL to manipulate exactly 2 types of elements: nodes and leaves. Nodes would be groups of nodes or (inclusive) leaves, and leaves would be the "widgets". My current thinking is that they can actually be described without using the usual inheritance/derivation hell that can be found in toolkits I've played with, one just need to define a number of rules to describe which values the content should accept.
That language would be spoken on stdin and stdout, of course, and if asked to not expect a client, the rendering would be a fdisk-like menu interface. Otherwise, clients could connect to that server, maybe spawned by the server itself, to do the rendering.

This is a tool I need in order to achieve other bigger projects, aka build my own distro. This tool would allow me to use shell scripts to build system tools that could be usable with: ssh, TTY, X11, framebuffer... and, yes, I suppose wayland too.

I really started to think on this when I wrote a tiny shell script allowing to manage runit daemons, and noticed that a lot of the complexity directly comes from dialog itself.
Here is the script, that I place on CC-0 license (no, I don't think I've published it):

Code:
#!/bin/sh

# This script aims to offer a friendly interface to manage runit services

# Requires:

# * dialog

# * find

# * $SVDIR which indicates the supervision folder

# * $SVKNOWN which indicates a colon-separated list of places to search for

#     existing services (duplicated services are *not* supported... yet?)

# * $ACTION indicates how to manipulate services

#

# Currently supported $ACTION values:

# * install: allows to register/unregister known services;

#

# Planned to support $ACTION values:

# * enable: allows to enable/disable known services;

# * toggle: same, via down file;

printf "SVDIR=%s\nSVKNOWN=%s\n" ${SVDIR:="/etc/service"} ${SVKNOWN:="/etc/sv/"} >&2

ACTION="enable"

SV_LIST=""

FINDOPT="-mindepth 1 -maxdepth 2 -name run "

for SOURCE in $(printf ${SVKNOWN} | tr ':' '\t')

do

    SV_LIST="$SV_LIST    $(find -H $SOURCE $FINDOPT -exec sh -c \

        'printf "%s %s off\n" $(dirname {}) $(dirname {})' \; | sort)"

done

SV_ENABLED=$(find -L ${SVDIR} $FINDOPT -exec sh -c \

    'printf " -e '\''/%s off$/ s/off$/on/g'\'' " $(basename $(dirname {}))' \;)

SV_CURRENT=$(printf "%s %s %s\n" $SV_LIST | eval sed $SV_ENABLED)

DIALOG=$(mktemp -d)

dialog --no-tags --checklist "List of service to $ACTION:" 0 0 0 $SV_CURRENT 2> $DIALOG/out

SV_NEW_ENABLED=$(tr ' ' '\n' < $DIALOG/out | awk -F/ '{printf " -e '\''/%s off$/ s/off$/on/g'\'' \n", $NF}END{printf "\n"}')

SV_NEXT=$(printf "%s %s %s\n" $SV_LIST | eval sed $SV_NEW_ENABLED)

printf "%s\n" "$SV_CURRENT" > $DIALOG/curr

printf "%s\n" "$SV_NEXT" > $DIALOG/next

AWKPROG='

{

    if( $2 != $3 )

    {

        if( $2 == "on" )

        {

            last = split( $1, elem, "/" );

            printf "rm %s/%s\n", svdir, elem[last];

        }

        else

        {

            printf "ln -s %s %s/\n", $1, svdir;

        }

    }

}

'

paste -d ' ' $DIALOG/curr $DIALOG/next | cut -f1,3,6 -d ' ' | awk -F' ' -v svdir="$SVDIR" "$AWKPROG"

rm -r $DIALOG