echo $SHELL # the shell
echo $BASH_VERSION # bash version
echo $$ # pid of current process
echo $! # pid of recently invoked background job
echo $? # exit code of previously executed command
VAR=value # set var
export VAR=value # export the value - will be available on sub-processes
VAR="String" # string quoted
echo ${#VAR} # length of string
#blah.sh param1 param2 param3 param4 param5
echo $0 # path of script calling
echo $1 # param1
echo $2 # param2