echo / printf

echo [options] [string...]
printf format [arguments...]

Command / Format	Description
echo string	Prints the string followed by a newline.
echo -n string	Prints the string without a trailing newline.
echo -e string	Interprets backslash escape sequences (e.g., \n, \t, \033[).
echo $variable	Expands and prints the value of a variable.
printf "%s\n" string	Outputs a string using a format specifier.
printf "%d\n" number	Outputs a value as an integer.
printf "%05d\n" number	Outputs a value zero-padded to 5 digits.
printf "%.2f\n" number	Outputs a value with 2 decimal places.
printf "%10s\n" string	Outputs a string right-aligned in a 10-character field.
printf "%-10s\n" string	Outputs a string left-aligned in a 10-character field.

Print a string using echo.

echo "Hello, World!"
Hello, World!

Expand and print the value of a variable.

greeting.sh

NAME="Alice"
echo "Hello, $NAME!"

bash greeting.sh
Hello, Alice!

Use the -n option to suppress the trailing newline. This is useful for inline prompts.

echo_n.sh

echo -n "Processing..."
echo " done!"

bash echo_n.sh
Processing... done!

Use the -e option to interpret escape sequences. This allows colored output.

color.sh

echo -e "\033[32mSuccess!\033[0m"
echo -e "\033[31mError!\033[0m"

bash color.sh
Success!
Error!

Use printf for formatted output, including integers and zero-padding.

printf "%d\n" 42
42

Output a zero-padded sequence. Useful for generating filenames.

numbering.sh

for i in 1 2 3; do
    printf "file_%03d.txt\n" $i
done

bash numbering.sh
file_001.txt
file_002.txt
file_003.txt

You can also enter a for loop directly in the terminal. After pressing Enter following do, a > prompt appears — this means input is still expected. Enter done to execute.

for i in 1 2 3; do
    printf "file_%03d.txt\n" $i
done
file_001.txt
file_002.txt
file_003.txt

Use printf to format tabular output. %-10s is left-aligned in a 10-character field, and %5d is right-aligned in a 5-character field.

table.sh

printf "%-10s %5s\n" "Name" "Score"
printf "%-10s %5d\n" "Alice" 95
printf "%-10s %5d\n" "Bob" 87

bash table.sh
Name       Score
Alice         95
Bob           87

For portable scripts, '$ printf' is preferred over '$ echo -e'. The behavior of '$ echo -e' varies between shells and implementations, whereas '$ printf' is defined by the POSIX standard and behaves consistently.

To read a line from standard input, use read. To write output to a file, see redirection (>).