Bash if-else statements

1. How do you write an IF ELSE statement in bash?
2. How do you write multiple if else statements in shell script?
3. What is else if in bash?
4. Can you put IF statement in if statement?
5. What is $? In Bash?
6. How do I get input in bash?
7. How do you set a variable in bash?
8. How do I see condition in bash?
9. How do I run a bash script?
10. How do you increment in bash?
11. What is Fi in if statement?
12. What is exit in bash?

How do you write an IF ELSE statement 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;

How do you write multiple if else statements in shell script?

To use multiple conditions in one if-else block, then elif keyword is used in shell. If expression1 is true then it executes statement 1 and 2, and this process continues. If none of the condition is true then it processes else part.

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.

Can you put IF statement in if statement?

You can put an if statement inside another if statement.

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.

How do I get input in bash?

Example 1:

1. #!/bin/bash.
2. # Read the user input.
3. echo "Enter the user name: "
4. read first_name.
5. echo "The Current User Name is $first_name"
6. echo.
7. echo "Enter other users'names: "
8. read name1 name2 name3.

How do you set a variable in bash?

To create a variable, you just provide a name and value for it. Your variable names should be descriptive and remind you of the value they hold. A variable name cannot start with a number, nor can it contain spaces. It can, however, start with an underscore.

How do I see condition in bash?

1. Single-bracket syntax

1. File-based conditions. Allows different kinds of checks on a file. Example: if [ -L symboliclink ]; then. ...
2. String-based conditions. Allows checks on a string and comparing of strings. Example one: if [ -z "$emptystring" ]; then. ...
3. Arithmetic (number-based) conditions. Allows comparing integer numbers.

How do I run a bash script?

Make a Bash Script Executable

1. 1) Create a new text file with a . sh extension. ...
2. 2) Add #!/bin/bash to the top of it. This is necessary for the “make it executable” part.
3. 3) Add lines that you'd normally type at the command line. ...
4. 4) At the command line, run chmod u+x YourScriptFileName.sh. ...
5. 5) Run it whenever you need!

How do you increment in bash?

Using + and - Operators

The most simple way to increment/decrement a variable is by using the + and - operators. This method allows you increment/decrement the variable by any value you want.

What is Fi in if statement?

Advertisements. The if... fi statement is the fundamental control statement that allows Shell to make decisions and execute statements conditionally.

What is exit in bash?

Bash provides a command to exit a script if errors occur, the exit command. The argument N (exit status) can be passed to the exit command to indicate if a script is executed successfully (N = 0) or unsuccessfully (N != 0). If N is omitted the exit command takes the exit status of the last command executed.