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- single quoting (e.g. 'some text') – this serves two purposes
- it groups together all text inside the quotes into a single token
- it tells the shell not to "look inside" the quotes to perform any evaluation
- all metacharacters inside the single quotes are ignored
- in particular, any environment variables in single-quoted text are not evaluated
- double quoting (e.g. "some text") – also serves two purposes
- it groups together all text inside the quotes into a single token
- it allows environment variable evaluation, but inhibits some metacharcters
- e.g. asterisk ( * ) pathname globbing (more on globbing later...)
- and some other metacharacters
- double quoting also preserves any special characters in the text
- e.g. newlines (\n) or Tabs (\t)
- backtick quoting (e.g. `date`)
- evaluates the expression inside the backtick marks ( ` )
- the standard output of the expression replaces the text inside the backtick marks ( ` )
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