This is the best way. It's also the way the Shellcheck wants sometimes recommends.

This is the way

I also do this so the variables are more easily spotted.

This is the right way

This has never stuck with me, and I hadn't thought about why until now. I have two reasons why I will always write ${x}_$y.z instead of ${x}_${y}.z:

• Syntax highlighting and shellcheck have always caught the cases I need to add braces to prevent $x_ being expanded as ${x_}.
• I write a lot of Zsh. In Zsh, braces are optional in way more cases. "$#array[3]" actually prints the length of the third item in array, rather than (Bash:) the number of positional parameters, then the string 'array[3]'.

when you're paid by character written

no eval ?

This really enterprises my bash.

@ilega_dh You don't need cat in cases when grep "d" alphabet.txt can read from file too. Edit: But obviously your comment was more of a joke to over complicate it. So never mind then.

What should I search to better understand what is written here? Don't mind learning myself, just looking for the correct keywords. Thanks!