Sending Nulls
In Chapter 6 (p. 153), I described how to detect a null character. A null can be sent by calling send with the -null flag. By default, one null is sent to the currently spawned process.
send -null
An optional integer may be used to send several nulls. For example, the following command sends three nulls.
send -null 3
send uses the pattern "-null" while expect uses "null“. The absence of a hyphen is historical—all of the special patterns lack a hyphen.
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