if [] do
then
fi 

-d file    Test if file is a directory
-e file    Test if file exists
-f file    Test if file is an ordinary file
-r file    Test if file is readable
-w file    Test if file is writable
-x file    Test if file is executable

n1 -eq n2    Test if n1 equals n2
n1 -ne n2    Test if n1 is not equal to n2
n1 -lt n2    Test if n1 is less than n2
n1 -le n2    Test if n1 is less than or equal to n2
n1 -gt n2    Test if n1 is greater than n2
n1 -ge n2    Test if n1 is greater than or equal to n2