set blabla {http://www.ietf.org/rfc/rfc3986.txt} if {regexp -- {^(https?://[a-z0-9\-+\.a-z0-9\-\.+(?:/|(?:/a-zA-Z0-9!#\$%&'\*\+,\-\.:;=\?@[\_~]+)*)))$} $blabla match url]} {
puts "$url is a valid url."
}
let's test it and post results here...
PS: don't work for ipv6 yet