Basic if statement

#!/bin/bash

FIRST_NUMBER=1
SECOND_NUMBER=2

if [ $FIRST_NUMBER -eq $SECOND_NUMBER ]
  then
    echo "FIRST_NUMBER equals SECOND_NUMBER"
elif [ $FIRST_NUMBER -lt $SECOND_NUMBER ]
  then
    echo "FIRST_NUMBER is less than SECOND_NUMBER"
elif [ $FIRST_NUMBER -gt $SECOND_NUMBER ]
  then
    echo "FIRST_NUMBER is greater than SECOND_NUMBER"
else
  echo "$FIRST_NUMBER and $SECOND_NUMBER are not numerically comparable"
fi

Numeric comparison operators

Operator Ruby-esque English
-eq == Equals
-ne != Does not equal
-lt < Less than
-le <= Less than or equal to
-gt > Greater than
-ge >= Greater than or equal to