13.4 Interactive File Control: int, pause, cont

If input is coming from an external file, the system treats it as a batch processed calculation. If you desire interactive response in this case, you can include the command on int; in the file. Likewise, you can issue the command off int; in the main program if you do not desire continual questioning from the system. Regardless of the setting of the switch int, input commands from a file are not kept in the system, and so cannot be referenced using input or ws, or edited using ed. However, an implementation of REDUCE may provide a link to an external system editor that can be used for such editing. The specific instructions for the particular implementation should be consulted for information on this.

Two commands are available in REDUCE for interactive use of files. pause; may be inserted at any point in an input file. When this command is encountered on input, the system prints the message Cont? (Y or N) on your terminal and halts. If you respond y (for yes), the calculation continues from that point in the file. If you respond n (for no), control is returned to the terminal, and you can input further statements and commands. Later on you can use the command cont; to transfer control back to the point in the file following the last pause; encountered. A top-level pause; from the terminal has no effect.

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