[krunaldo]

Wrong!

echo, true, false and [ are builtins in bash and are in the binary. You can even do TCP/UDP through bash by using the pretend redirect files /dev/(tcp|udp)/$host/$port.

curl or wget exists on most systems by default in a minimal installation now days, nc does not, but if you run a normal installation you will get it though.

[JosephRedfern]

   josephredfern@ubuntu:~$ which [
   /usr/bin/[

[Daviey]

Use 'type', not 'which'

[LukeShu]

It exists as both an external program, and as a builtin

    $ type [
    [ is a shell builtin