Differences

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--- bash:if...then...else [2019/12/12 20:31] – peter
+++ bash:if...then...else [2021/05/28 08:42] (current) – peter
@@ Line 8: / Line 8: @@
 STATEMENTS
 fi
-</code
+</code>
-The statements are only executed given the CONDITION is true.
+<WRAP info>
+**NOTE:**  The statements are only executed if the CONDITION is true.
 The **fi** keyword is used for marking the end of the **if** statement.
+</WRAP>
@@ Line 32: / Line 35: @@
 </code>
-The above program will only show the output if the number provided via input is greater than ten.
+<WRAP info>
+**NOTE:**  The above program will only show the output if the number entered is greater than ten.
-The **-gt** stands for greater than; similarly **-lt** for less than; **-le** for less than equal; and **-ge** for greater than equal. The **<nowiki>[[ ]]</nowiki>** are required.
+The space around the **<nowiki>[[ ]]</nowiki>** are required!
+  * **-gt**:  stands for greater than;
+Similarly:
+  * **-lt**:  for less than.
+  * **-le**:  for less than or equal.
+  * **-ge**:  for greater than or equal.
+</WRAP>
 ----
@@ Line 54: / Line 70: @@
 </code>
-The **else** part needs to be placed after the action part of **if** and before **fi**.
+<WRAP info>
+**NOTE:**  The **else** part needs to be placed after the action part of **if** and before **fi**.
+</WRAP>
+----
+===== Using Elif =====
+The **elif** statement stands for 'else if' and offers a convenient means for implementing chain logic.
+<code bash>
+#!/bin/bash
+echo -n "Enter a number: "
+read num
+if [[ $num -gt 10 ]]
+then
+echo "Number is greater than 10."
+elif [[ $num -eq 10 ]]
+then
+echo "Number is equal to 10."
+else
+echo "Number is less than 10."
+fi
+</code>
+----
+===== AND =====
+Use **&&**.
+<code bash>
+#!/bin/bash
+echo -n "Enter Number:"
+read num
+if [[ ( $num -lt 10 ) && ( $num%2 -eq 0 ) ]]; then
+echo "Even Number"
+else
+echo "Odd Number"
+fi
+</code>
+----
+===== OR =====
+Use **||**.
+<code bash>
+#!/bin/bash
+echo -n "Enter any number:"
+read n
+if [[ ( $n -eq 15 || $n -eq 45 ) ]]
+then
+echo "You won"
+else
+echo "You lost!"
+fi
+</code>
+----
+===== References =====
+See [[BASH:Switch|Switch]]