**Decision-making** is the act of performing different actions based on different conditions. 

The following are the two types of decision-making statements we can use in Unix/Linux shell:
1. **The if-else statement**: If-else statements are useful to take a path from a given set of paths based on the given conditions.

* **if-fi**: The *if* block is executed if the specified condition is true.
* **if-else-fi**: The *if* block is executed if the specified condition is true. Otherwise, the *else* block is executed.
* **if-elif-else-fi**: The *if* block is executed if the condition specified in the *if* statement is true. Otherwise, the next *elif* condition is checked. The *elif* block is executed if the condition specified in the *elif* statement is true. The process goes on for the remaining *elif* statements until no condition is satisfied. If none of the conditions of *if* or *elif* statements are satisfied, the *else* block is executed.
2. **The case-sac statement:**
Case-sac statements are similar to switches. They are useful when all of the different branches only depend on the value of a single input variable.

## Comparison operators
### 1. Binary operators
- **String comparison operators** compare strings. The following illustration shows some valid string comparisons.

- **Numeric comparison operators** compare numeric values. The table below shows some valid numeric comparisons.

|Comparison|Interpretation|
|---|---|
|$x -eq $y|$x is equal to $y|
|$x -ne $y|$x is not equal to $y|
|$x -lt $y|$x < $y|
|$x -gt $y|$x > $y|
|$x -le $y|$x <= $y|
|$x -ge $y|$x >= $y|

### 2. Logical operators
**Logical operators** are used to combine different binary operators.
- AND operator: &&
- OR operator: ||
- NOT operator: !

## Code
The codes below explain the usage of both decision-making methods.

### 1. The if-else statement



score=73
if [ "$score" -ge 90 ]; then
  echo "A*"
elif [ "$score" -ge 80 ]; then
  echo "A"
elif [ "$score" -ge 70 ]; then
  echo "B"
elif [ "$score" -ge 60 ]; then
  echo "C"
elif [ "$score" -ge 50 ]; then
  echo "D"
else
  echo "F"
fi

temp="Algorithms"
case "$temp" in
  "Databases")  echo "Databases are simply magical!";;
  "Operating Systems") echo "Operating Systems are awesome :)";;
  "Algorithms") echo "I love Algorithms <3";;
esac

How to do the decision-making in Unix/Linux shell

Comparison operators

1. Binary operators

2. Logical operators

Code

1. The if-else statement

2. The case-sac statement

Comparison	Interpretation
$x -eq $y	$x is equal to $y
$x -ne $y	$x is not equal to $y
$x -lt $y	$x < $y
$x -gt $y	$x > $y
$x -le $y	$x <= $y
$x -ge $y	$x >= $y