HPlogo Command Interpreter Access and Variables Programmer's Guide: Series HP 3000 Computer Systems > Chapter 8 Command Input/Output Redirection (CIOR)

Stacked I/O Redirection

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I/O redirection may be done even if I/O has already been redirected.

For example, say you have created a command file named SHOW, which contains the following:

   parm showdest="$STDLIST"

   showme

   showout >!showdest

   showvar

   showjob >>!showdest ;job=!hpuser.!hpaccount

Now let's say you set a file equation for printer LP602 and invoke SHOW as follows:

   show outfile >*lp602

After variable substitution and I/O redirection, this results in the following sequence of commands and output destinations:

showme output to lp602 (spoolfile) showout output to a temporary file named outfile showvar output to lp602 (a new spoolfile) showjob output appended to the temporary file outfile

Output from the showme and showvar commands goes to the device defined by the file equation for lp602.

Output from the showout command is redirected to the file outfile and output from showjob is appended to outfile. This occurs because the entire show command file has its output redirected to LP602. But inside the command file, the showout and showjob commands redirect output (again) to the temporary file name outfile.

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