write shell script

#!/bin/sh # cd to fbshop-casperjs directory cd $(dirname $0)/.. casperjs src/shop/crawl/[login to view URL] $* exit $? I have script above. some worker call that script continuously 24H. I would like to modify like below. I don't know how to control value and if condition in shell script. $i should be stored somewhere outside to increase the value for every independent excution of .sh script. Environment of this script on Ubuntu 14.X.X #!/bin/sh # cd to fbshop-casperjs directory cd $(dirname $0)/.. if($i is not exist){ $i=0 } if($i == 200){ $i=0 } if($* contain "[login to view URL]"){ if($i <100){ casperjs src/shop/crawl/[login to view URL] $* } else{ casperjs --ignore-ssl-errors=true src/shop/crawl/[login to view URL] $* } $i=$i+1 } else{ casperjs --ignore-ssl-errors=true src/shop/crawl/[login to view URL] $* } exit $?