Translate, squeeze, or delete characters in text streams.
low risk
tr translates or transforms characters — replacing, deleting, or squeezing repeated characters. Only works on stdin/stdout, not files directly. Frequently used for case conversion, removing unwanted characters, and cleaning data.
| Flag | Meaning |
|---|---|
-d --delete | Delete specified characters |
-s --squeeze-repeats | Squeeze repeated characters to one |
-c --complement | Use complement of the character set |
echo 'Hello World' | tr '[:upper:]' '[:lower:]'Convert to lowercase · explain & risk-check →echo 'hello' | tr 'a-z' 'A-Z'Convert to uppercase · explain & risk-check →cat file.txt | tr -d '\r'Remove Windows carriage returns · explain & risk-check →echo 'a b c' | tr -s ' 'Squeeze multiple spaces to one · explain & risk-check →Use `tr -d '\r'` to fix Windows line endings in scripts cloned on Linux — a common cause of 'bad interpreter' errors.
Reference text is hand-written and may be incomplete — check man tr for your version. Test destructive commands on a non-production system first.