How can I tell if STDIN is connected to a terminal in Perl?
if (-t STDIN) {
# stdin is connected
} else {
# stdin is not connected
}
I usually use this in conjunction with -t STDOUT, to find out if I'm running from an interactive shell, or from cron, to enable more output.
You might also be interested in IO::Interactive to figure out if Perl thinks it is interacting with a user. Simply being connected to a tty doesn't mean the user is going to see what you do.
One solution would be to use tty:
[root@server] ~> tty
/dev/pts/0
[root@server] ~> echo y | tty
not a tty
But not very pretty...
来源：https://stackoverflow.com/questions/528781/how-can-i-tell-if-stdin-is-connected-to-a-terminal-in-perl