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Upcasing with `tr`

💡 tr translates characters from one set to another.

Basic Usage

echo "hello world" | tr '[:lower:]' '[:upper:]'
# HELLO WORLD

Character Classes

# Using POSIX character classes
echo "MiXeD CaSe" | tr '[:lower:]' '[:upper:]'
# MIXED CASE

# Using character ranges
echo "hello123" | tr 'a-z' 'A-Z'
# HELLO123

Real World Example

Convert filenames to uppercase:

for file in *.txt; do
  mv "$file" "$(echo "$file" | tr '[:lower:]' '[:upper:]')"
done

💡 Unlike awk or sed, tr is specifically designed for character-by-character transformations, making it faster for simple case conversions.

Useful Aliases

Add these to your .bashrc or .zshrc for quick case conversion:

alias upcase="tr '[:lower:]' '[:upper:]'"
alias downcase="tr '[:upper:]' '[:lower:]'"

Now you can use them like:

echo "make me loud" | upcase
# MAKE ME LOUD

echo "MAKE ME QUIET" | downcase
# make me quiet

# Chain them together
echo "MiXeD" | downcase | upcase
# MIXED

# Or with files
cat README.md | upcase

Resources

man tr

🎉 Happy coding!

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