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How To Use Case Statements on Bash Script in Oracle Linux 9.4

To Use Case Statements On Bash Script In Oracle Linux 9.4

Introduction:

The fundamental syntax of the case...esac statement involves providing an expression to evaluate and executing various statements based on the value of that expression. The interpreter assesses each case in relation to the expression's value until a match is identified. If no matches are found, a default condition will be applied.

Procedure:

Step 1: Check the OS version

[root@localhost ~]# cat /etc/os-release
NAME="Oracle Linux Server"
VERSION="9.4"
ID="ol"
ID_LIKE="fedora"
VARIANT="Server"
VARIANT_ID="server"
VERSION_ID="9.4"
PLATFORM_ID="platform:el9"
PRETTY_NAME="Oracle Linux Server 9.4"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:9:4:server"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://github.com/oracle/oracle-linux"
ORACLE_BUGZILLA_PRODUCT="Oracle Linux 9"
ORACLE_BUGZILLA_PRODUCT_VERSION=9.4
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=9.4

Step 2: Create the script file

[root@localhost ~]# vi case_script_1
#!/bin/bash
echo "Which color do you like best?"
echo "1 - Blue"
echo "2 - Red"
echo "3 - Yellow"
read color;
case $color in
  1) echo "Blue is a primary color.";;
  2) echo "Red is a primary color.";;
  3) echo "Yellow is a primary color.";;
  *) echo "This color is not available. Please choose a different one.";; 
esac

Step 3: Change the permissions by using following command

[root@localhost ~]# chmod +x case_script_1

Step 4: Run the script by using following command

[root@localhost ~]# ./case_script_1
Which color do you like?
1 - Blue
2 - Red
3 - Yellow
1
Blue is a primary color
[root@localhost ~]# ./case_script_1
Which color do you like?
1 - Blue
2 - Red
3 - Yellow
2
Red is a primary color
[root@localhost ~]# ./case_script_1
Which color do you like?
1 - Blue
2 - Red
3 - Yellow
3
Yellow is a Primary color
[root@localhost ~]# ./case_script_1
Which color do you like?
1 - Blue
2 - Red
3 - Yellow
4
This color is not valid, select another one

Step 5:Create the another script

[root@localhost ~]# vi case_script_2
read fruit
case $fruit in
    "banana" | "papaya" | "mango")
        echo "It's a tropical fruit!"
        ;;
    *)
    echo "It's not a tropical fruit"
    ;;
esac

Step 6: Change the permissions by using following command

[root@localhost ~]# chmod +x case_script_2

Step 7: Run the script file by using following command

[root@localhost ~]# ./case_script_2
Enter any fruit name? 
banana
is's a tropical fruit!
[root@localhost ~]# ./case_script_2
Enter any fruit name? 
Papaya
is's a tropical fruit!
 [root@localhost ~]# ./case_script_2
Enter any fruit name? 
graphes
is's not a tropical fruit

Conclusion:

We have reached the end of this article. In this guide, we have walked you through the steps required to use Case Statements on Bash Script in Oracle Linux 9.4 Your feedback is much welcome.

Tag : Bash-scripting Linux OracleVM
FAQ
Q
What is the main use of a case statement?
A
The CASE statement in SQL returns a value for the condition specified. It tests a list of conditions and returns one of the multiple possible results. We mostly use a case expression in SQL stored procedures or as a formula for a particular column which optimizes the SQL statements.
Q
Why use case esac statement?
A
esac statement is to give an expression to evaluate and execute several different statements based on the value of the expression. The interpreter checks each case against the value of the expression until a match is found. If nothing matches, a default condition will be used.
Q
How to ignore a case in a shell script?
A
Another approach to case-insensitive comparisons is to enable the nocasematch option within the shell. To conduct a case-insensitive string comparison, we follow these steps: enable the nocasematch option. perform the string comparison test using the [[ ]]
Q
What is the difference between case and if in shell script?
A
When to use If-else vs a Case statement. Much like the if-then-else statement, the bash case statement is a conditional statement used to vary the flow of your shell script. While the if-else statement is used to choose between two options, the case statement is helpful when you have multiple different choices.
Q
What is the purpose of the case statement in shell scripting?
A
Case statements test input values until they match a pattern, executing the command linked with that input value. This makes it an excellent choice for menus where users can select an item to perform a matching action.