Text Case Conversion in Bash – Commands & Examples
Published 2026-03-06 · convertcase.in
Bash offers multiple ways to change text case — from the tr command to modern Bash 4+ parameter expansion. Here's a complete guide.
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1Using tr
echo "HELLO" | tr "[:upper:]" "[:lower:]" → "hello" echo "hello" | tr "[:lower:]" "[:upper:]" → "HELLO"
2Bash 4+ Parameter Expansion
str="HELLO WORLD"
echo "${str,,}" → "hello world" (lowercase)
echo "${str^^}" → "HELLO WORLD" (uppercase)3Using awk
echo 'hello' | awk '{print toupper($0)}' → 'HELLO'Frequently Asked Questions
Does Bash have built-in case conversion?
Bash 4+ has ${var,,} for lowercase and ${var^^} for uppercase. Older Bash versions need tr or awk.