A Clear Comparison Between `echo` and `printf` in Shell Scripting

Comparison of echo and printf

In shell scripting, the echo and printf commands are commonly used for output, but they differ significantly in functionality and behavior.

1. Basic Functionality

• echo is used for simple output of strings or variable values. It's useful for quickly displaying results without formatting.
• printf provides precise control over the output format and works similarly to the printf function in C.

Example

echo "Hello, world!"         # Outputs: Hello, world!
printf "Hello, world!\n"     # Outputs: Hello, world!

2. Escape Sequence Handling

• echo can interpret escape sequences like \n or \t when used with the -e option in some shells like Bash. However, behavior varies between shells, and in some environments, the -e may be ignored or printed as plain text.
• printf always interprets escape sequences by default and behaves consistently across different environments.

Example

echo -e "Line1\nLine2"       # Line1 (newline) Line2
printf "Line1\nLine2\n"      # Line1 (newline) Line2

3. Line Break Handling

• echo automatically includes a newline (\n) at the end of the output. To suppress it, use the -n option.
• printf does not include a newline by default. You must explicitly add \n if needed.

Example

echo -n "No newline"         # Outputs: No newline (no line break)
printf "No newline"          # Outputs: No newline (no line break)

4. Complex Formatting

• echo can only output plain text and doesn’t support formatting like decimal places or alignment.
• printf lets you control the output format, such as showing numbers with a fixed number of decimal places.

Example

echo "Price: 3.14159"                      # Outputs: Price: 3.14159
printf "Price: %.2f\n" 3.14159             # Outputs: Price: 3.14

In the printf example, %.2f means “print the number with 2 digits after the decimal point.” This is helpful when you need cleaner, consistent output.

5. Portability

• echo behaves differently depending on the shell. Options like -e and -n are not standardized by POSIX, which can lead to inconsistent results across systems.
• printf is a POSIX-standard command and behaves consistently on nearly all Unix-like systems, making it more reliable for portable scripts.

Example

echo -e "Tab\tSpace"         # May interpret tab in Bash, may show -e literally in Dash
printf "Tab\tSpace\n"        # Always outputs: Tab    Space