Modules in Bash or AWK

Configuration Other languages
1

Hi there,

for quite a while now I’m fumbling trying to get a working fvwm module written either as a shell or an awk script, but I never
really managed to get to the point where the module would be able to send commands to fvwm.
With the shell script I always get an error complaining about the sent string being to big.
With awk I even do not come to that point as I have no idea howto write to a file descriptor.
In one of the topics I read about a module written as a shell script but I didn’t find any source code. It seems to be vanished…
The background is that my fvwm runs on a Zaurus and I try to avoid installing perl in order to save precious disk space.
On the other hand I would like to handle key bindings without the Exec command as it costs too much time to open
a shell each time you want to adjust the volume for mplayer.

Maybe one of you fvwm (or shell or awk) experts can help me by giving me some hints?

Thanks a lot in advance.

Christoph

2

There was an unfinished attempt by someone to write sh bindings to talk to FVWM.

Redirection.

Maybe you can tell us what it is you’re really trying to do – it could simply be running an external script using FvwmCommand or just PipeRead suffices, rather than shooting yourself.

– Thomas Adam

3

Hi Thomas,

here comes my attempt in awk:

#!/bin/bash

awk '

  BEGIN {
    send_text("\000");
    send_text("NOP FINISHED STARTUP");
    send_text("Echo Test");
  }

  function send_text(text) {
    print text
  }
  
' 1>&$1 <&$2

I would expect a “Test” in .xsession-errors. But nothing happens.

The shell module is nearly the same:

#!/bin/bash
echo "0" >&$1
echo "NOP FINISHED STARTUP" "0" >&$1
echo "0" >&$1
echo "Echo Test" >&$1

Same result. Nothing in .xsession-errors.

The reasons I try to do this is that a Piperead or Exec would start a shell that e.g. would itself start an xmmsctrl command.
Increasing the volume that way wouldn’t be very responsive as the Zaurus is simply too slow for that. So I thought of using
the xmms-pipe plugin with an fvwm-module that translates and passes the commands directly to the plugin. Same idea
with mplayer in slave-mode.
And, of course, I have kind of a sportive interest in just seeing if it is possible. :slight_smile:

Christoph

4

Doesn’t running a bash or awk script use the same resources for opening a shell as pipeexec? I tried it anyway
to see if it would work.

You have the module protocol slightly wrong. A message to fvwm is:
4 bytes for the window id
4 bytes for the message length
the message as an ascii string
4 bytes for continue (1 or 0)

With echo, the numbers have to be sent as binary by converting them to octal escape sequences. Also
echo adds a newline by default, which will affect the data.

So this is the bash fvwm module:

[code]#!/bin/bash

echo -ne “\000\000\000\000” >&$1
echo -ne “\024\000\000\000” >&$1
echo -n “NOP FINISHED STARTUP” >&$1
echo -ne “\001\000\000\000” >&$1

echo -ne “\000\000\000\000” >&$1
echo -ne “\011\000\000\000” >&$1
echo -n “echo Test” >&$1
echo -ne “\001\000\000\000” >&$1[/code]

5

Or just use printf.

– Thomas Adam

6

I’m a wee bit late to the party, but did anyone pursue this further?
I cannot, for the life of me, get the posted code to work.

I’d like to take bash as a basis for an early prototype module, using it wrapped inside Haskell’s Turtle Library.

The error I get when launching the module from the FVWM Commandline is the following:

 [fvwm][module_receive]: <<ERROR>> Module(0x22d8b80) command is too big (5282239978490842958), limit is 1000
7

I have a crontab tcsh script which uses FvwmCommand, and another one which is called periodically by an FvwmScript invoked by the .fvwmrc (this pings a few local hosts and sets the colour of a little widget as green or red whether they respond or not). I have also another one called by a single PipeRead from .fvwmrc