Shell

Working with IF, ELSE and ELSE IF in Bash Shell Scripting

Working with IF, ELSE and ELSE IF in Bash Shell Scripting
  1. How do you write an if else condition in shell script?
  2. Can we use else if in shell script?
  3. Can you have multiple Elif in bash?
  4. How do you write multiple If statements in bash?
  5. What is $? In Bash?
  6. What is another name for a bash shell script?
  7. What is if Z in shell script?
  8. How do you terminate a shell script if statement?
  9. How do I debug a shell script?
  10. What is else if in bash?
  11. Is there else if in bash?
  12. How do you do if in bash?

How do you write an if else condition in shell script?

Their description with syntax is as follows:

  1. if statement. This block will process if specified condition is true. ...
  2. if-else statement. ...
  3. if..elif..else..fi statement (Else If ladder) ...
  4. if..then..else..if..then..fi..fi..(Nested if) ...
  5. Syntax: case in Pattern 1) Statement 1;; Pattern n) Statement n;; esac. ...
  6. Example 2:

Can we use else if in shell script?

Conditions in Shell Scripts

An if-else statement allows you to execute iterative conditional statements in your code. We use if-else in shell scripts when we wish to evaluate a condition, then decide to execute one set between two or more sets of statements using the result.

Can you have multiple Elif in bash?

If the TEST-COMMAND2 evaluates to True , the STATEMENTS2 will be executed. If none of the test commands evaluate to True , the STATEMENTS2 is executed. You can have one or more elif clauses in the statement. The else clause is optional.

How do you write multiple If statements in bash?

In order to execute a Bash “if else” statement, you have to use four different keywords : if, then, else and fi :

  1. if : represents the condition that you want to check;
  2. then : if the previous condition is true, then execute a specific command;
  3. else : if the previous condition is false, then execute another command;

What is $? In Bash?

$? is a special variable in bash that always holds the return/exit code of the last executed command. You can view it in a terminal by running echo $? . Return codes are in the range [0; 255]. A return code of 0 usually means everything is ok.

What is another name for a bash shell script?

Bash (AKA Bourne Again Shell) is a type of interpreter that processes shell commands. A shell interpreter takes commands in plain text format and calls Operating System services to do something.

What is if Z in shell script?

The -z flag causes test to check whether a string is empty. Returns true if the string is empty, false if it contains something. NOTE: The -z flag doesn't directly have anything to do with the "if" statement. The if statement is used to check the value returned by test.

How do you terminate a shell script if statement?

The value of N can be used by other commands or shell scripts to take their own action. If N is omitted, the exit status is that of the last command executed. Use the exit statement to terminate shell script upon an error. If N is set to 0 means normal shell exit.

How do I debug a shell script?

Bash shell offers debugging options which can be turn on or off using the set command:

  1. set -x : Display commands and their arguments as they are executed.
  2. set -v : Display shell input lines as they are read.

What is else if in bash?

The elif (else if) is used for multiple if conditions. In case if the first condition goes false then check another “if” conditions. In the following example, we are taking input from the user and display corresponding statements. Use “if” condition to check if the marks are greater or equal to 80.

Is there else if in bash?

Bash – If-elif-else Statement Example

The elif (else if) is used for multiple if conditions. In case one if the condition goes false then check another if conditions. For example, input the marks of a student and check if marks are greater or equal to 80 then print “Very Good”.

How do you do if in bash?

A Shell script usually needs to test if a command succeeds or a condition is met. In Bash, this test can be done with a Bash if statement.
...
What are the Bash Conditional Expressions?

Conditional ExpressionMeaning
-a fileTrue if file exists.
-b fileTrue if file exists and is a block special file.

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