The * prototype forces the argument expression to be evaluated in scalar context. Furthermore, if the argument expression is an identifier but not an operator, the identifier will be passed as a string ("auto-quoted"). This allows one one to create subs with the same interface as open and read.

The $ prototype forces the argument expression to be evaluated in scalar context.

The semi-colon separates the required arguments (on the left) from the optional ones (on the right).

sysreadline($foo)          Passes $foo
sysreadline(FOO)           Passes "FOO"
sysreadline($foo, $bar)    Passes $foo and $bar
sysreadline(FOO, $bar)     Passes "FOO" and $bar
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