<P> expr is a command line Unix utility which evaluates an expression and outputs the corresponding value . It first appeared in Unix v7 . </P> <P> Syntax: expr expression </P> <P> expr evaluates integer or string expressions, including pattern matching regular expressions . Each symbol (operator, value, etc .) in the expression must be given as a separate parameter . Most of the challenge posed in writing expressions is preventing the invoking command line shell from acting on characters intended for expr to process . </P> <P> The operators available </P>

What is the purpose of expr in shell script
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