Re: What is wrong with a regex?

[Peng Yu]

On 2/3/23, Koichi Murase <myoga.murase@gmail.com> wrote:
> 2023年2月4日(土) 12:44 Peng Yu <pengyu.ut@gmail.com>:
>> $ f=row.txt; [[ $f =~ ^row([0-9]*)(\|_x)[.]txt$ ]]; echo $?
>> 1
>
> You need to write (|_x) instead of (\|_x). In the conditional command
> [[ ... ]], the character `|' loses the original meaning of the pipe
> operator, so you can directly specify it without quoting. If you quote
> it as \|, it becomes a regular expression that matches a literal
> single character `|'.

That would be a syntax error as the return status 2 indicates.

$ f=row.txt; [[ $f =~ ^row([0-9]*)(|_x)[.]txt$ ]]; echo $?
2

> $ [[ '|' =~ \| ]]; echo $?
> 0
>


-- 
Regards,
Peng