read

The read builtin utility is used to parse input into a variable.

One of its most common uses is to get input from a user via stdin, but it can be used in other ways as well.

Using read

Getting User Input

Typically when prompting for user input, you'd use read.

#!/bin/bash

declare MY_VAR

read -r -p "Enter input: " MY_VAR

printf "You entered: %s\n" "$MY_VAR"

• read -r -p "Enter input: " MY_VAR:
  • -r: Do not expand escape sequences (e.g., \n)
  • -p "Enter input: ": Show this prompt to the user (Enter input:).
  • MY_VAR: The variable name to save the input into.

This is a very simple way to interactively get input from a user and save it into a variable.

Reading Programmatically with read

The read builtin can also be used to parse lines into an array.

To do so, you direct an input stream to read via stdin, either via pipe (|) or input redirection (<).

#!/bin/bash

declare MY_FILE='./file.txt'
declare -a LINES
IFS=$'\n' read -r -d '' -a LINES < "$MY_FILE"

printf "File: %s\n" "${LINES[@]}"

• IFS=$'\n': Set the internal field separator to a newline so elements are read into the array line-by-line.
• -d '': This tells read to read until end of file (EOF), rather than end of line (EOL).
• -a LINES: Specify the array to read into.