caret

^old^new[^]

^ in shell has multiple meanings:History substitution: ^old^new is a shortcut for !!:s/old/new/, replacing text in the previous command. Quick fix for typos without retyping.Regular expression anchor: ^ matches the start of a line. ^hello matches lines starting with "hello".Character class negation: [^abc] matches any character except a, b, or c.Exponentiation: In $((...)) and some languages, ^ may be XOR or exponent (use ******** in bash for exponent).

^old^new

Replace first occurrence of old with new in the previous command and execute it.

Same substitution; the trailing ^ is optional unless appending additional text.

Equivalent long-form history substitution syntax.

Replace all occurrences of old with new in the previous command.

^old^new only replaces the first occurrence. For global replacement, use !!:gs/old/new/.In some shells/contexts, ^ may need escaping or behave differently.The caret substitution must be at the start of the command line.

bash(1), history(1), grep(1), sed(1)