how to pass keyboard input along to linux command?

I run a l开发者_如何学JAVAinux command that sometimes asks for user input (press 1 or 2).

I always want to answer 1, how can I pass this value automatically ?

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Use the pipe | operator to connect the output of one command to the input of another.

echo 1 | command

If you want to repeat some input to a command, you can use yes. By default it sends the string "y" repeatedly but it also repeat a different string of your choice.

yes | cp * /tmp  # Answer "y" to all of cp's "Are you sure?" prompts.
yes 1 | command  # Answer "1" repeatedly until the command exits.

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Just a thought:

echo "1" | linux_command --with-arguments <&0

This works for commands which want input from stdin, because 0 is the descriptor for standard input. This question might better belong on Server Fault however...

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yes 1 | command