How to set read command to execute without having

Question

I use the below code to assign a given by the user character to variable G:

read G

However in order to move forward with executing of my script I need to press enter button. Is it possible to set the read command somehow that it show process forward to the next line immediately after it receive the one letter from stdin?

Answer 1

I thought dd might be able to do this, so I tried it out and didn't get anywhere. However, Google found this for me and I adapted it here:

readOne () {
    local oldstty
    oldstty=$(stty -g)
    stty -icanon -echo min 1 time 0
    dd bs=1 count=1 2>/dev/null
    stty "$oldstty"
}

Define this function once at the beginning of your script, then you can use it like this:

char=$(readOne)    # get the character
echo $char         # print the character (or you can do something else with it)

Answer 2

If you're using Bash:

read -n1 G

Your system is configured to use dash by default and dash doesn't support this feature, so you also need to change the first line of your script to specify that you wish you use bash:

#!/bin/bash