csplit regex multiple digits between "[" and "]"

Question

I want to split txt file on string "Template[0]", "Template[1]" etc.

The command below works until "Template[10]"

csplit -k cert_templates.txt '/Template\[[0-9]\]:/' {*}

I tried those but they did'nt work

csplit -k cert_templates.txt '/Template\[([0-9]+)\]:/' {*}

csplit -k cert_templates.txt '/Template\[[0-9]+\]:/' {*}

This works for "Template[10]" + until "Template[100]"

csplit -k cert_templates.txt '/Template\[[0-9][0-9]\]:/' {*}

What regex should i use to work with undefined number of digits?

Any help would be much appreciated.

Answer 1

The regex flavor used by this csplit requires that '+', if it is to match a sequence of 1 or more, is preceded by a backslash, i. e. Template\[[0-9]\+\].

Answer 2

This regex will suffice: ^\d+$

To break this down, the \d means any digit and the + means one or more.