So I was thinking about this some more while waiting for my wife to pick me up. I'm not crazy about making system calls, but it's not a critical feature and I could error-check for the existence of the system commands and if it's not present, I can just make an arbitrary decision. But here was my idea: 
sleep 10 | perl -e '$ppid=getppid();$sibs=`pgrep -P $ppid`;print("MY P
+ID: $$\nPARENT: $ppid\nSIBLINGS: $sibs\n")'
MY PID: 79496
PARENT: 563
SIBLINGS: 79495

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It doesn't work all the time. If I run a short command, like echo, I don't get that PID: 
echo test | perl -e '$ppid=getppid();$kids=`pgrep -P $ppid`;print("MY 
+PID: $$\nPARENT: $ppid\nSIBLINGS: $kids\n")'
MY PID: 79493
PARENT: 563
SIBLINGS:

[download]
Plus, this doesn't tell me about whether or not I'm running inside a shell script. I couldn't find a perl module that does what pgrep does.

In reply to Re: Can a script tell if it is being run from inside a script versus in an interactive terminal session? by hepcat72
in thread Can a script tell if it is being run from inside a script versus in an interactive terminal session? by hepcat72

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