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About bash : Passing-arguments-to-an-interactive-program-non-interactively

Question Detail

I have a bash script that employs the read command to read arguments to commands interactively, for example yes/no options. Is there a way to call this script in a non-interactive script passing default option values as arguments?

It’s not just one option that I have to pass to the interactive script.

Question Answer

Many ways

pipe your input

echo "yes
no
maybe" | your_program

redirect from a file

your_program < answers.txt

use a here document (this can be very readable)

your_program << ANSWERS
yes
no
maybe
ANSWERS

use a here string

your_program <<< $'yes\nno\nmaybe\n'

For more complex tasks there is expect ( http://en.wikipedia.org/wiki/Expect ).
It basically simulates a user, you can code a script how to react to specific program outputs and related stuff.

This also works in cases like ssh that prohibits piping passwords to it.

You can put the data in a file and re-direct it like this:

$ cat file.sh
#!/bin/bash

read x
read y
echo $x
echo $y

Data for the script:

$ cat data.txt
2
3

Executing the script:

$ file.sh < data.txt
2
3

Just want to add one more way. Found it elsewhere, and is quite simple.
Say I want to pass yes for all the prompts at command line for a command “execute_command”, Then I would simply pipe yes to it.

yes | execute_command

This will use yes as the answer to all yes/no prompts.

You can also use printf to pipe the input to your script.

var=val
printf "yes\nno\nmaybe\n$var\n" | ./your_script.sh

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