Bash Conditional Statements

In Bash Scripts the following conditional expressions can be used.

if-else-fi

A single condition can be implemented as:

if [ <condition> ]
then
    <do something>
else
    <do something>
fi

where the else part is optional but the spaces on both sides of the brackets [] are not.

if-elif-else-fi

Several conditions can be implemented with:

if [ <condition1> ]
then
    <do something>
elif
then
    <do something>
else
    <do something>
fi

Switch Cases

Execute the statement corresponding to the pattern that <expressions> is equal to.

The syntax is:

case <expression> in
    pattern1 ) statements1 ;;
    pattern2 ) statements2 ;;
    pattern3 ) statements3 ;;
esac