Re: Useless Use Of Regexes

On 3/24/25 20:34, Lawrence D'Oliveiro wrote:

Besides the traditional “Useless Use Of Cat” (UUOC) newbie faux pas,
we can add “Useless Use Of Regexes”.
 These can often be quite subtle. I spotted one obvious instance here
<https://www.zdnet.com/article/5-ways-i-use-regex-in-linux-and-why-theyre-so-essential/>,
namely this one:
      ip addr | grep -Eo '192\.168\.1\.[0-9]{1,3}'
 

Tut Tut!
$ip addr | grep -E '192\.168\.0\.([0-1]?[0-9]?[0-9]?|2[0-4][0-9]|25[0-5])'
Solve a problem with a RegEx, now you have two problems :-)

which can be more easily written using features built into iproute2 itself:
      ip addr show to 192.168.1.0/24

Seriously, though, it is often easier to filter output from a standard command with grep, than it is to learn all the command flags.