I have a desire to know what the controlling terminal is for my process. As a test, I wanted to see some differences between jobs I start from a UNIX shell and those I start as UNIX cron jobs. Using Proc::ProcessTable gives me the results I would expect: The shell jobs, no matter how I start or background them, have a ttynum value greater than zero. For cron jobs ttynum is -1. However, using the POSIX ctermid function, I get /dev/tty no matter how the jobs is started.

This is Solaris 2.8, Perl 5.6.1. I'd also use it under Perl 5.8.0 but I haven't tried it there yet.

Update: It looks like ctermid just gives you back a path name you can use to open a controlling terminal. For the cron jobs, attempts to open that device fail. That tells me what I need to know.

In reply to Controlling Terminal Accuracy by steves

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