How to control servo cam pan/tilt using bash and servoblaster?

Question

Hello everybody,

I'm trying to make a script bash to move a cam with servoblaster. when I strike a lettre (i,o,l,p) I would like increment or decrement a variable, to move the camera degree by degree or percent

My problem I can't adapt my command echo P1-11=90% >/dev/servoblaster to a variable to increase or decrease the nomber 90%. this is my code:

#!/bin/sh

#ServoBlaster

sudo /home/user/PiBits/ServoBlaster/user/./servod --p1=11,12

readkeyboard=`stty -icanon ; dd bs=1 count=1 2>/dev/null`

if [ "$readkeyboard" = 'o' ]; then i=$((i+1))  echo P1-11=$i >/dev/servoblaster #up

elif [ "$readkeyboard" = 'l' ]; then i=$((i-1)) echo P1-11=$i >/dev/servoblaster #down

elif [ "$readkeyboard" = 'i' ]; then i=$((i+1)) echo P1-12=$i >/dev/servoblaster #left

elif [ "$readkeyboard" = 'p' ]; then i=$((i-1)) echo P1-12=$i >/dev/servoblaster #right 

fi

done

Thank you in advance for your help.

Finally I have found, This is my code:

#!/bin/sh
#echo p1-22=250 > /dev/servoblaster #angle
#echo P1­-11=80% > /dev/servoblaster #pourcent


#ServoBlaster

#$i=90
#$s=90
sudo /home/user/PiBits/ServoBlaster/user/./servod --p1=11,12

while(true);do

readkeyboard=`stty -icanon ; dd bs=1 count=1 2>/dev/null`

if [ "$readkeyboard" = 'l' ]; then i=$((i+1)) ;  echo P1-11=$i >/dev/servoblaster #up

elif [ "$readkeyboard" = 'o' ]; then i=$((i-1)) ;  echo P1-11=$i >/dev/servoblaster #down

elif [ "$readkeyboard" = 'i' ]; then s=$((s+1)) ; echo P1-12=$s >/dev/servoblaster #left

elif [ "$readkeyboard" = 'p' ]; then s=$((s-1)) ; echo P1-12=$s >/dev/servoblaster #right 


fi

clear
done

Answer 1

Your shell script is wrong. You need a semicolon between the reassignment of i and echo so that they are run as two separate commands.

Also, this has nothing to do with Raspberry Pi; it's a shell question.