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The bash program below is a (test) program to test the values of a USB
interface card.

The lines in front are only for clarification.

When an input port on the USB card gets activated, then the variable
digital_inputs changes (in line 11).
I checked that with line 12
The next time the while statement executes (in line 8) it should be false,
and the while loop should stop.

This doesn't happen.

What is my mistake? (don't get a syntax error)



1#!/bin/bash
2
3 digital_inputs=0
4 portstatus_dec=0
5
6
7
8 while [ $digital_inputs=$portstatus_dec ];
9 do
10 sleep 1
11 digital_inputs=`k8055 -m:1 2>/dev/null | tail -1 | cut -d';' -f2`
12 echo $digital_inputs
13 done
14
15 echo "There is an alarm"

On Wed, 27 Feb 2008 21:01:49 +0100, Henk Oegema wrote:

> The bash program below is a (test) program to test the values of a USB
> interface card.
>
> The lines in front are only for clarification.
>
> When an input port on the USB card gets activated, then the variable
> digital_inputs changes (in line 11).
> I checked that with line 12
> The next time the while statement executes (in line 8) it should be
> false, and the while loop should stop.
>
> This doesn't happen.
>
> What is my mistake? (don't get a syntax error)
>
>
>
> 1#!/bin/bash
> 2
> 3 digital_inputs=0
> 4 portstatus_dec=0
> 5
> 6
> 7
> 8 while [ $digital_inputs=$portstatus_dec ]; 9 do

In a test, you need a space on each side of the equals sign.

> 10 sleep 1
> 11 digital_inputs=`k8055 -m:1 2>/dev/null | tail -1 | cut -d';'
> -f2` 12 echo $digital_inputs
> 13 done
> 14
> 15 echo "There is an alarm"

El Tux <nope@spamsucks.invalid>:
> On Wed, 27 Feb 2008 21:01:49 +0100, Henk Oegema wrote:
> >
> > 1#!/bin/bash
> > 2
> > 3 digital_inputs=0
> > 4 portstatus_dec=0
> > 8 while [ $digital_inputs=$portstatus_dec ];
>
> In a test, you need a space on each side of the equals sign.

And, to quote Ben at linuxgazette.net, *always* double-quote your
variables. They may be empty.

> > 10 sleep 1
> > 11 digital_inputs=`k8055 -m:1 2>/dev/null | tail -1 | cut -d';' -f2`
> > 12 echo $digital_inputs
> > 13 done
> > 14
> > 15 echo "There is an alarm"


--
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(*) http://blinkynet.net/comp/uip5.html Linux Counter #80292
- - http://www.faqs.org/rfcs/rfc1855.html Please, don't Cc: me.

s. keeling wrote:

>
> And, to quote Ben at linuxgazette.net, *always* double-quote your
> variables. They may be empty.
>
Yep.

Henk Oegema <henk@oegema.com> writes:

>The bash program below is a (test) program to test the values of a USB
>interface card.

>The lines in front are only for clarification.

>When an input port on the USB card gets activated, then the variable
>digital_inputs changes (in line 11).
>I checked that with line 12
>The next time the while statement executes (in line 8) it should be false,
>and the while loop should stop.

>This doesn't happen.

>What is my mistake? (don't get a syntax error)

Put spaces on either side of the = in test.




>1#!/bin/bash
>2
>3 digital_inputs=0
>4 portstatus_dec=0
>5
>6
>7
>8 while [ $digital_inputs=$portstatus_dec ];
>9 do
>10 sleep 1
>11 digital_inputs=`k8055 -m:1 2>/dev/null | tail -1 | cut -d';' -f2`
>12 echo $digital_inputs
>13 done
>14
>15 echo "There is an alarm"