[Q] shell scripting syntax? - Sony Xperia P, U, Sola, Go

This is actually related to the Xperia U but i'm sure it will be identical for the Xperia S and P.
Via tasker i'm running a Shell script to control the LED bar lights used during a notification.
I've found a way to acces them and turn each LED on/off (left-middle-right and colors) but now I'm looking for the right syntax to increase and decrease the value of one LED so I can make them fade in en out.
Via Pent (tasker) I've got this (only fade in):
dir=/sys/class/leds;
val=0;
while [ $val != 256 ];
do
echo $val > $dir/m-key-red/brightness;
echo $val > $dir/m-key-green/brightness;
echo $val > $dir/m-key-blue/brightness;
let val=$val+1;
done
but I continue to get the error let: arith: syntax error: "val=0+1" which is an indication that i'm using the wrong syntax.
does anyone know which syntax to use within the Xperia NXT 2012 shell?
ps. i'm aware of the illumination bar notification app, but would very much like to create my own

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let val = $val + 1
Also you don't need semicolons after every line.

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K900 said:
let val = $val + 1
Also you don't need semicolons after every line.
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my bad, made a typing error in the first post.
I did use let val=$val+1 (now corrected in first post)
when I try it now again (to double check) it still gives the same error

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Looks like it only likes it bash style.
val=$(($val+1))

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mmh..
if I do it like this:
dir=/sys/class/leds
val=0
while [$val != 255]
do
echo $val > $dir/m-key-red/brightness
echo $val > $dir/m-key-green/brightness
echo $val > $dir/m-key-blue/brightness
let val=$(($val + 1 ))
done
Click to expand...
Click to collapse
Then I get this error> while not found
and if I do it like this:
dir=/sys/class/leds
val=0
while ($val != 255)
do
echo $val > $dir/m-key-red/brightness
echo $val > $dir/m-key-green/brightness
echo $val > $dir/m-key-blue/brightness
let val=$(($val + 1 ))
done
Click to expand...
Click to collapse
I get this error > Syntax error: "(" unexpected
I'm not too familiar with scripting, but usually manage to adjust stuff once it works.. but it doesn't seem to want to work

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It's while < clause >; do

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nope, then I get again the " while: not found " error.
an alternative would be to create an array and cycle through all numbers instead of a while construction.. or would that be too intense? + how to do that?
(i only know half of what I'm doing.. will promise not to venture further in to scripting.. just need this damn fade in/fade out to work)

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nixx-X1 said:
nope, then I get again the " while: not found " error.
an alternative would be to create an array and cycle through all numbers instead of a while construction.. or would that be too intense?
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Click to collapse
Derp. [ square brackets not ( round ones in your clause.

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dir=/sys/class/leds; val=0; while ($val != 255); do echo $val > $dir/m-key-red/brightness; echo $val > $dir/m-key-green/brightness; echo $val > $dir/m-key-blue/brightness; let val=$(($val + 1 )); done
will give me the following error:
0: not found.

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nixx-X1 said:
Code:
dir=/sys/class/leds; val=0; while ($val != 255); do echo $val > $dir/m-key-red/brightness; echo $val > $dir/m-key-green/brightness; echo $val > $dir/m-key-blue/brightness; let val=$(($val + 1 )); done
will give me the following error:
0: not found.
Click to expand...
Click to collapse
your while is not correct something like this should work.
Code:
dir=/sys/class/leds
val=0
[B][COLOR="Red"]while (("$val" < "256")); do
[/COLOR][/B]
echo $val > $dir/m-key-red/brightness
echo $val > $dir/m-key-green/brightness
echo $val > $dir/m-key-blue/brightness
let val=$((val + 1 ))
done
the problem is the $val was being "called" instead of checked (thats my take on it anyway)

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any chance you tested this on an Xperia U?
Just quickly tried, but got a while error again.
will check later in de afternoon double if I didn't put anything wrong in it

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nixx-X1 said:
any chance you tested this on an Xperia U?
Just quickly tried, but got a while error again.
will check later in de afternoon double if I didn't put anything wrong in it
Click to expand...
Click to collapse
You need [ in place of ((
---------- Post added at 02:25 PM ---------- Previous post was at 02:20 PM ----------
Code:
led() {
echo $1 > /sys/class/leds/m-key-$2/brightness
}
val=0
while [ $val -lt 256 ]; do
led $val red
led $val green
led $val blue
val=$(($val + 1))
done
Here you go. led() is just a small helper function that works led <number> <color>

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K900 said:
You need [ in place of ((
---------- Post added at 02:25 PM ---------- Previous post was at 02:20 PM ----------
Code:
led() {
echo $1 > /sys/class/leds/m-key-$2/brightness
}
val=0
while [ $val -lt 256 ]; do
led $val red
led $val green
led $val blue
val=$(($val + 1))
done
Here you go. led() is just a small helper function that works led <number> <color>
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Thanks I thought I had it wrong.
Pvy
Sent from my LT18i using xda premium

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and i'm still going nuts
seems to work everywhere but here.
when I copy & paste it, it doesn't work, when I write the it in 1 line in the terminal it neither works.
In both cases it gives the following error:
Sytax error: " do" unexpected (expecting "}")
then when I make this of it:
led() {
echo $1 > /sys/class/leds/m-key-$2/brightness
}
val=0
while [ $val -lt 256 ];
{do
led $val red
led $val green
led $val blue
val=$(($val + 1))}
done
Click to expand...
Click to collapse
it does go to the next line, but doesn't do anything or show an error
btw.. sending a simple echo does work and function as expected. (eg. echo 250 /sys/class/leds/m-key-red/brightness)

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nixx-X1 said:
and i'm still going nuts
seems to work everywhere but here.
when I copy & paste it, it doesn't work, when I write the it in 1 line in the terminal it neither works.
In both cases it gives the following error:
Sytax error: " do" unexpected (expecting "}")
then when I make this of it:
it does go to the next line, but doesn't do anything or show an error
Click to expand...
Click to collapse
You have an extra { just before do. And it likely won't work in your shell if you just copy/paste.

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thanks, but doesn't work either..
do you have an xperia U and tested if the middle led light will fade in if you write this?

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nixx-X1 said:
thanks, but doesn't work either..
do you have an xperia U and tested if the middle led light will fade in if you write this?
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Click to collapse
I don't have the device on me, I only have bash.

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ok, are there multiple versions of bash, could that be the reason? (still on andriod 2.3.7 btw)
if so, what version you have?

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nixx-X1 said:
ok, are there multiple versions of bash, could that be the reason? (still on andriod 2.3.7 btw)
if so, what version you have?
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Show the output when you run it please.
Also I'm pretty sure you need to run that as root.

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I am running it as root (first command is "su") and the terminal emulator is a system app as well.
It's a crappy app though as it only shows one line.
this is what I typed first:
led() { echo $1 > /sys/class/leds/m-key-$2/brightness } val=0 while [ $val -lt 256 ]; do led $val red led $val green led $val blue val=$(($val + 1)) done
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Click to collapse
2nd line is:
led() { echo $1 > /sys/class/leds/m-key-$2/brightness } val=0 while [ $val -lt 256 ]; {do led $val red led $val green led $val blue val=$(($val + 1))} done
Click to expand...
Click to collapse
3rd line is:
led() { echo $1 > /sys/class/leds/m-key-$2/brightness } val=0 while [ $val -lt 256 ]; {do led $val red led $val green led $val blue val=$(($val + 1)) done
Click to expand...
Click to collapse