Unix: How to use Bash backticks recursively

Question

Either I missed some backlash or backlashing does not seem to work with too much programmer-quote-looping.

$ echo "hello1-`echo hello2-\`echo hello3-\`echo hello4\`\``"

hello1-hello2-hello3-echo hello4

Wanted

hello1-hello2-hello3-hello4-hello5-hello6-...

Answer 1

It's a lot easier if you use bash's $(cmd) command substitution syntax, which is much more friendly to being nested:

$ echo "hello1-$(echo hello2-$(echo hello3-$(echo hello4)))"
hello1-hello2-hello3-hello4

Answer 2

Use $(commands) instead:

$ echo "hello1-$(echo hello2-$(echo hello3-$(echo hello4)))"
hello1-hello2-hello3-hello4

$(commands) does the same thing as backticks, but you can nest them.

You may also be interested in Bash range expansions:

echo hello{1..10}
hello1 hello2 hello3 hello4 hello5 hello6 hello7 hello8 hello9 hello10

Answer 3

if you insist to use backticks, following could be done

$ echo "hello1-`echo hello2-\`echo hello3-\\\`echo hello4\\\`\``"

you have to put backslashes, \\ \\\\ \\\\\\\\ by 2x and so on, its just very ugly, use $(commands) as other suggested.