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register s ^aS^i^ac
bindkey ^a,, process s
Nas profundezas do manual da tela:
register [-e encoding] key string
Save the specified string to the register key. The encoding of the string can be specified via the -e option. See also the "paste" command.
e:
process [key]
Stuff the contents of the specified register into screen's input queue. If no argument is given you are prompted for a register name. The text is parsed as if it had been typed in from the user's keyboard. This command can be used to bind multiple actions to a single key.