Here strings (<<<) in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this Bash script using here string?

Consider the following Bash script snippet. What will it print when executed?

Bash Scripting

read line <<< "Hello World"
echo "$line"

A read: command not found

B line

C Hello World

D Hello

💡 Hint

The here string sends the string as input to the read command.

The read command reads the string "Hello World" from the here string and stores it in the variable 'line'. Then echo prints the full string.

💻 Command Output

intermediate

What does this script output when using here string with a loop?

What will be printed by this Bash script?

Bash Scripting

while read word; do
  echo "$word"
done <<< "one two three"

A one two three

B one

C

one two
three

D

one
two
three

💡 Hint

The here string sends the entire string as a single line to the loop.

The here string sends the whole string as one line, so the loop reads it once and prints it once.

📝 Syntax

advanced

Which option correctly uses a here string to count words?

Which of the following Bash commands correctly counts the number of words in the string "apple banana cherry" using a here string?

A wc -w < "apple banana cherry"

B wc -w <<< "apple banana cherry"

C wc -w << "apple banana cherry"

D wc -w <<< apple banana cherry

💡 Hint

Here strings use <<< followed by a quoted string.

Option B correctly uses <<< with a quoted string to send input to wc. Option B uses incorrect syntax for here document. Option B tries to redirect a file named "apple banana cherry". Option B misses quotes causing syntax error.

🔧 Debug

advanced

Why does this script fail to assign the variable correctly?

What is the error in this Bash script and why does it not assign the variable 'var' as expected? var=$(read line <<< "test") echo "$var"

A The read command does not output anything, so var is empty

B Syntax error: missing quotes around read

C read command cannot be used with here strings

D The variable 'line' is not declared

💡 Hint

The read command reads input but does not print it.

The read command reads input into 'line' but does not output it. Using command substitution captures output, so var is empty.

🚀 Application

expert

How to use here string to pass multiple lines to a command?

You want to pass multiple lines of text to a command using a here string. Which option correctly does this in Bash?

A

grep 'pattern' <<< line1
line2
line3

B

grep 'pattern' <<< "line1
line2
line3"

C

grep 'pattern' <<< 'line1
line2
line3'

D grep 'pattern' <<< $'line1\nline2\nline3'

💡 Hint

Use $'...' to interpret escape sequences inside a here string.

Option D uses $'...' syntax to interpret \n as newlines, passing multiple lines correctly. Option D passes literal \n characters, not newlines. Option D passes literal backslash and n characters. Option D is invalid syntax.