Question

Following the shell script that I am executing

#!/bin/sh

echo "Enter [y/n] : "
read opt

Its output is

Enter [y/n] : 
Y

I want that the variable should be read on the same line like below

Enter [y/n] : Y

Should be simple I guess, but I am new to bash scripting.

Answer 1

The shebang #!/bin/sh means you’re writing code for either the historical Bourne shell (still found on some systems like Solaris I think), or more likely, the standard shell language as defined by POSIX. This means that read -p and echo -n are both unreliable.

The standard/portable solution is:

printf 'Enter [y/n] : '
read -r opt

(The -r prevents the special treatment of \, since read normally accepts that as a line-continuation when it’s at the end of a line.)

If you know that your script will be run on systems that have Bash, you can change the shebang to #!/bin/bash (or #!/usr/bin/env bash) and use all the fancy Bash features. (Many systems have /bin/sh symlinked to bash so it works either way, but relying on that is bad practice, and bash actually disables some of its own features when executed under the name sh.)