How do I input from statement in bash script?

Question

I have the following bash script, saved as script.sh:

echo "Do that? [Y,n]"
read input
if [[ $input == "Y" || $input == "y" ]]; then
        echo "do that"
else
        echo "don't do that"
fi

On the terminal, I would like to run the script together with input in a single line. I attempted

./trial.sh < y

However, I receive the following output

bash: y: No such file or directory

How can I resolve this?

If you write <foo, you are redirecting from a file named foo. In your case, a file named y would be needed. The file does not exist, and hence the error message. — user1934428
– user1934428, Commented Oct 29, 2019 at 6:54

Benjamin W. · Accepted Answer · 2019-10-29 02:14:03Z

2

Redirection with < expects a filename to read standard input from. You could

use a here-doc:
```
./trial.sh <<'EOF'
y
EOF
```
use a here-string:
```
./trial.sh <<< y
```
print a y and send it to standard input with a pipe:
```
printf 'y' | ./trial.sh
```
or use the yes tool, which does exactly that:
```
yes | ./trial.sh
```
yes can also send other strings: yes n prints n instead of y.

Side note: your script can be shortened to

read -rp "Do that? [Y,n] " input
if [[ $input == [Yy] ]]; then
    echo "do that"
else
    echo "don't do that"
fi

answered Oct 29, 2019 at 2:14

Benjamin W.

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Comments

John Kugelman · Accepted Answer · 2019-10-29 02:01:22Z

1

When you redirect stdin using the < the next token on the command line is expected to be a filename -- thus the error message...

Instead, try "piping" the Input string "y" into your command, like so:

echo "y" | ./script.sh

John Kugelman

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answered Oct 29, 2019 at 1:50

SteveR

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