I have two problems, and it would be great if someone could help me:

The first line does not calculate. I have checked the origin term to calculate the variables
and the result is OK. Normal substactions with $xx -100 work, but not in this constallation. I tried it with "| bc" and no result too.

x= $((y - z))

 echo "$x"
 a=`echo "$x"-10 | bc`
 echo "$a"

 if [ `echo "$a" > 0  | bc` ]
   then sendme /rsi/logs/csc_summary_size_check.log stefan.madre
 fi

Hi,

Welcome to the unix and linux forum !!

Please use code tags for your data samples and code.

Try this one,

First way:
x=1
y=2
z=0
((z=x+y))
echo ${z}

Second way:
x=1
y=2
z=0
z=$(echo "$x+$y"|bc)
echo ${z}

Thank you. It works.