In Bash, you can convert lines containing spaces into a string array where each line is an element of the array. Here's how you can do it:

Method 1: Using readarray (or mapfile)

If you have a multi-line string or a file with lines containing spaces, you can use readarray (or its synonym mapfile) to read the lines into an array.

Example:

# Example multi-line string with spaces
input="line one
line two with spaces
line three"

# Use readarray to split into an array
readarray -t array <<< "$input"

# Print each element of the array
for element in "${array[@]}"; do
    echo "$element"
done

Explanation:

• readarray -t array <<< "$input" reads the lines of $input into the array array.
• The -t option removes the trailing newline from each line.
• "${array[@]}" expands to all elements of the array, each as a separate word.

Method 2: Using IFS and read

If you want to read from a file or a command output, you can use IFS (Internal Field Separator) and read:

Example:

# Example file with lines containing spaces
file="example.txt"

# Read file into an array
IFS=$'\n' read -d '' -ra array < "$file"

# Print each element of the array
for element in "${array[@]}"; do
    echo "$element"
done

Explanation:

• IFS=$'\n' sets the Internal Field Separator to a newline, so read splits on newlines.
• read -d '' -ra array < "$file" reads the entire file into the array array.
• "${array[@]}" expands to all elements of the array.

Method 3: Using while loop

If you want to process each line as it is read (e.g., from a file or command output), you can use a while loop:

Example:

# Example file with lines containing spaces
file="example.txt"

# Initialize an empty array
array=()

# Read file line by line
while IFS= read -r line; do
    array+=("$line")
done < "$file"

# Print each element of the array
for element in "${array[@]}"; do
    echo "$element"
done

Explanation:

• while IFS= read -r line reads each line of the file into the variable line.
• array+=("$line") appends each line to the array array.
• "${array[@]}" expands to all elements of the array.

Key Notes:

• Always use "${array[@]}" to expand the array, as this preserves spaces and special characters in each element.
• Avoid using for line in $(cat file) or similar constructs, as they split on spaces and break lines with spaces into multiple elements.