Bash Read User Input

Bash Read User Input

To read user input from bash terminal, use read command followed by the variable names.

In this tutorial, we shall learn to read input provided by user through bash shell (Terminal), using example bash scripts.

Syntax of Read Command

read is a bash builtin command to read input from user. read command reads only a single line from bash shell. Following is the syntax of read command

read <variable_name>

Example – Read Input from User via Terminal

Following is an example Bash Script to read user input using read command.

Bash Script

#!/bin/bash

echo "Enter your name.."
read name
echo "Hello $name ! Learn to Read input from user in Bash Shell"

In this example, third line, echo command is used to prompt user for an input.

Fourth line, read command reads user input via keyboard, to a variable named name.

Fifth line, echo command uses name variable to display to the terminal.

Output

$ ./bash-readinput-example 
Enter your name..
Arjun
Hello Arjun ! Learn to Read input from user in Bash Shell

Read input to multiple variables in a single read command

You may also read input to multiple variables in a single read command.

In the following example, we shall read firstname followed by lastname in a single read command.

Bash Script

#!/bin/bash

echo "Enter your FirstName LastName.."
read firstname lastname
echo "Hello $firstname ! Heard that your last name is $lastname."

The user input is broken to parts at white-space characters and the chunks are assigned to respective variables. Following are the possible scenarios with the number of words and number of variables.

Scenario	Result
Number of Words = Number of Variables	Variables are assigned with words respectively
Number of Words < Number of Variables	Respective Words are assigned to Variables. Remaining variables remain empty.
Number of Words > Number of Variables	Respective Words are assigned to Variables. Except for the last variable is assigned the rest of input.

Based on this, the first example where we read a line to variable could be considered as a third scenario in the table above with number of variables = 1.

Output

$ ./bash-readinput-example-2 
Enter your firstname lastname..
Tutorial Kart
Hello Tutorial ! Heard that your last name is Kart.

$ ./bash-readinput-example-2 
Enter your firstname lastname..
X Y
Hello X ! Heard that your last name is Y.

arjun@arjun-VPCEH26EN:~/workspace/bash/readinput$ ./bash-readinput-example-2 
Enter your firstname lastname..
Monica  
Hello Monica ! Heard that your last name is .

Conclusion

In this Bash Tutorial, we learned how to read user input, entered via standard input, to a variable and use the value in the script.