$histchars  –  Control History Expansion, Quick Substitution, and Tokenization

$histchars contains up to three characters:

1. history expansion character: Defines the start of a history expansion. Default value: !.
2. quick substitution character: The character, which starts a substitution, when it’s first on a line. Default value: ^.
3. end-of-line comment character (optional): The character, where an end-of-line comment begins. Default value: #

Links

• Bash manual
• Bash manual on Event Designators

Examples

Quick substitution to print hello world

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echo hello # here comes the quick substitution # to replace "hello" of the previous # command with "hello world" and run it ^hello^hello\ world^

Now use a custom substitution character

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histchars='!@' echo hello @hello@hello\ world@