Parameter for Output Channels

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Parameter for Output Channels

Besides the log-file parameter, Interactive Optimizer and the Callable Library offer you output-channel parameters to give you finer control over when and where messages appear in the Interactive Optimizer. Output-channel parameters indicate whether output should or should not appear on screen. They also allow you to designate log files for message channels. The output-channel parameters do not affect the log-file parameter, so it is customary to use the command set logfile before the command set output channel value1 value2.

In the output-channel command, you can specify a channel to be one of dialog, errors, logonly, results, or warnings. Table 6.2 summarizes the information carried over each channel.

Table 6.2 Options for the Output-Channel Command
Channel	Information
`dialog`	messages related to interactive use; e.g., prompts, help messages, greetings
`errors`	messages to inform user that operation could not be performed and why
`logonly`	message to record only in file (not on screen) e.g., multiline messages
`results`	information explicitly requested by user; state, change, progress information
`warnings`	messages to inform user request was performed but unexpected condition may result

The option value2 lets you specify a file name to redirect output from a channel.

Also in that command, value1 allows you to turn on or off output to the screen. When value1 is y, output is directed to the screen; when its value is n, output is not directed to the screen. Table 6.3 summarizes which channels direct output to the screen by default. If a channel directs output to the screen by default, you can leave value1 blank to get the same effect as set output channel y.

Table 6.3 Channels Directing Output to Screen or to a File
Channel	Default value1	Meaning
`dialog`	`y`	blank directs output to screen but not to a file
`errors`	`y`	blank directs output to screen and to a file
`logonly`	`n`	blank directs output only to a file, not to screen
`results`	`y`	blank directs output to screen and to a file
`warnings`	`y`	blank directs output to screen and to a file

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