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Command documentation sourced from the linux-command project This comprehensive command reference is part of the linux-command documentation project.

echo - Display a Line of Text

The echo command displays lines of text or string variables to the standard output. It's one of the most frequently used commands in shell scripting for displaying messages, debugging, and generating output.

Basic Syntax​

echo [SHORT-OPTION]... [STRING]...
echo LONG-OPTION

Common Options​

  • -n - Do not output the trailing newline
  • -e - Enable interpretation of backslash escapes
  • -E - Disable interpretation of backslash escapes (default)
  • --help - Display help information and exit
  • --version - Output version information and exit

Escape Sequences (with -e option)​

  • \a - Alert (bell)
  • \b - Backspace
  • \c - Produce no further output
  • \e - Escape character
  • \f - Form feed
  • \n - Newline
  • \r - Carriage return
  • \t - Horizontal tab
  • \v - Vertical tab
  • \\ - Backslash
  • \nnn - Character with octal value nnn
  • \xHH - Character with hexadecimal value HH

Usage Examples​

Basic Output​

# Simple text output
echo "Hello, World!"

# Multiple arguments
echo Hello World Linux

# Output without newline
echo -n "This continues on the same line"
echo " and this continues"

# Empty line
echo

Variable Expansion​

# Display environment variables
echo $HOME
echo $PATH
echo $USER

# Combine variables with text
echo "Welcome, $USER! Your home directory is $HOME"

# Command substitution
echo "Current directory: $(pwd)"
echo "Date and time: $(date)"

# Arithmetic expansion
echo "2 + 2 = $((2 + 2))"
echo "File count: $(ls | wc -l)"

Special Characters and Escaping​

# Using escape sequences
echo -e "Line 1\nLine 2\nLine 3"
echo -e "Column 1\tColumn 2\tColumn 3"
echo -e "Alert sound\a"

# Backspace and overwriting
echo -e "Loading...\b\b\bDone!"

# No further output after \c
echo -e "Progress: 50%\c"
echo "This won't be printed"

# Raw escape character
echo -e "Escape sequence: \e[31mRed text\e[0m"

Practical Examples​

Colored Output​

# Basic colors
echo -e "\e[31mRed text\e[0m"
echo -e "\e[32mGreen text\e[0m"
echo -e "\e[33mYellow text\e[0m"
echo -e "\e[34mBlue text\e[0m"
echo -e "\e[35mMagenta text\e[0m"
echo -e "\e[36mCyan text\e[0m"

# Background colors
echo -e "\e[41mRed background\e[0m"
echo -e "\e[42mGreen background\e[0m"
echo -e "\e[44mBlue background\e[0m"

# Text formatting
echo -e "\e[1mBold text\e[0m"
echo -e "\e[4mUnderlined text\e[0m"
echo -e "\e[5mBlinking text\e[0m"
echo -e "\e[7mReversed text\e[0m"

# Combined formatting
echo -e "\e[1;31;44mBold red text on blue background\e[0m"

Scripting and Automation​

# Progress indicators
echo -n "Installing package: "
for i in {1..5}; do
    echo -n "."
    sleep 1
done
echo " Done!"

# Status messages
echo "[INFO] Starting application..."
echo "[WARNING] Low disk space"
echo "[ERROR] Connection failed"

# File generation
echo "#!/bin/bash" > script.sh
echo "echo 'Hello from script'" >> script.sh
chmod +x script.sh

# Configuration files
echo "server_name = example.com" > config.conf
echo "port = 8080" >> config.conf
echo "debug_mode = true" >> config.conf

Data Processing​

# Create CSV data
echo "Name,Age,City" > data.csv
echo "John,25,New York" >> data.csv
echo "Jane,30,Los Angeles" >> data.csv

# Generate numbered list
for i in {1..10}; do
    echo "Item $i"
done

# File header creation
echo "Report generated on: $(date)" > report.txt
echo "================================" >> report.txt

# Log file creation
timestamp=$(date '+%Y-%m-%d %H:%M:%S')
echo "[$timestamp] Application started" >> app.log

System Administration​

# System status
echo "System information:"
echo "Hostname: $(hostname)"
echo "Kernel: $(uname -r)"
echo "Uptime: $(uptime)"
echo "Memory usage: $(free -h | grep Mem)"

# Service status
echo "Checking services..."
systemctl is-active nginx && echo "Nginx: Running" || echo "Nginx: Stopped"
systemctl is-active mysql && echo "MySQL: Running" || echo "MySQL: Stopped"

# User information
echo "Current user: $(whoami)"
echo "Groups: $(groups)"
echo "Shell: $SHELL"

Advanced Usage​

Complex Formatting​

# Table format
printf "%-15s %8s %10s\n" "Name" "Age" "City"
echo "-------------------------------"
printf "%-15s %8d %10s\n" "John" 25 "New York"
printf "%-15s %8d %10s\n" "Jane" 30 "Los Angeles"

# Progress bar
bar_length=50
progress=30
filled=$((progress * bar_length / 100))
empty=$((bar_length - filled))
echo -n "["
printf "%*s" $filled | tr ' ' '='
printf "%*s" $empty | tr ' ' '-'
echo "] $progress%"

Special Applications​

# ASCII art
echo "   __   _"
echo "  / _| | |"
echo " | |_  | | __ _  ___"
echo " |  _| | |/ _\` |/ __|"
echo " | |___| | (_| | (__"
echo " |______|_|\__,_|\___|"

# Box drawing
echo "+--------+--------+"
echo "|  Name  |  Age   |"
echo "+--------+--------+"
echo "|  John  |   25   |"
echo "+--------+--------+"

# Mathematical patterns
for i in {1..5}; do
    echo -n "$(printf "%*s" $i | tr ' ' '*') "
    echo
done

Debugging and Development​

# Debug output
debug() {
    [ "$DEBUG" = "true" ] && echo "[DEBUG] $1"
}

debug "Variable value: $variable"
debug "Function called with parameters: $@"

# Variable inspection
echo "Variable types:"
echo "STRING_VAR='$STRING_VAR'"
echo "NUMBER_VAR=$NUMBER_VAR"
echo "ARRAY_VAR=(${ARRAY_VAR[@]})"

# Function tracing
trace_execution() {
    echo "TRACE: Entering function $1"
    "$@"
    echo "TRACE: Exiting function $1"
}

File Operations​

File Creation and Writing​

# Create multiple files
for file in file1.txt file2.txt file3.txt; do
    echo "Content of $file" > "$file"
done

# Create structured data
cat << 'EOF' > structured_data.json
{
    "name": "example",
    "version": "1.0",
    "created": "$(date -Iseconds)"
}
EOF

# Multi-line content
echo "Line 1" > multiline.txt
echo "Line 2" >> multiline.txt
echo "Line 3" >> multiline.txt

Redirection and Pipes​

# Redirect to files
echo "Error message" >&2
echo "Log entry" >> application.log

# Pipe to other commands
echo "hello world" | tr '[:lower:]' '[:upper:]'
echo "file1 file2 file3" | xargs touch

# Here document alternative
echo "This is a long line
that spans multiple
lines" > multiline.txt

Performance Considerations​

Efficient Output​

# Multiple echoes vs single echo
# Less efficient:
echo "Line 1"
echo "Line 2"
echo "Line 3"

# More efficient:
echo -e "Line 1\nLine 2\nLine 3"

# For large amounts of data:
printf "%s\n" "Line 1" "Line 2" "Line 3"

# Using echo in loops efficiently
for i in {1..1000}; do
    echo "Line $i"
done > large_file.txt

Best Practices​

  1. Quote variables to prevent word splitting and glob expansion
  2. Use printf for complex formatting instead of echo
  3. Prefer echo -e over external echo for consistency
  4. Use appropriate quoting for special characters
  5. Consider printf for portability in scripts

Common Issues and Solutions​

Variable Expansion Problems​

# Problem: Unquoted variables
echo $path_with_spaces  # May split into multiple arguments

# Solution: Quote variables
echo "$path_with_spaces"  # Preserves spacing

Special Character Handling​

# Problem: Interpreted escape sequences
echo "C:\Users\Documents"  # \U might be interpreted

# Solution: Use -E or single quotes
echo -E "C:\Users\Documents"
echo 'C:\Users\Documents'

Portability Considerations​

# For maximum portability, use printf
printf "%s\n" "Hello, World!"
printf "Line 1\nLine 2\nLine 3\n"
  • printf - Format and print data
  • cat - Concatenate and display files
  • tee - Read from standard input and write to standard output and files
  • print - Shell builtin for printing
  • tput - Initialize a terminal or query terminfo database

The echo command is fundamental to shell scripting and command-line operations, providing a simple yet powerful way to generate output and display information.

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