^[_a-zA-Z0-9]+$ how to make regex username with underscore. i'm using c# but this regex isn't working.

Get the extension of file

fsdfsd

inverse match letters, numbers, and underscores

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This can be used to find all zone files that contain authoritative nameservers - e.g. perl -ne 'print if /^([\w.]+\.)\s+.+\sNS\s.+\1/' /var/named/*.db | awk '{print $1}' | sort | uniq

Remove repeated elements from a plain JSON array.