Why is it necessary to close standard input/output/error when writing a (unix) daemon?
Why is it necessary to close standard input/output/error when writing a (unix) daemon?
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Why is it necessary to close standard input/output/error when writing a (unix) daemon?
You don’t have to definitely close standard output/error, but you have to be sure where your daemon (and child) are going to writing to. Redirecting the output to a log file is a common practice.
Closing standard input is required so that the daemon (and/or child) doesn’t get stuck trying to read some input from the user.
But if you’re going to detach you daemon from a controlling TTY using
setsid(), the standard input/output/error are going to be invalid.