Some examples are GNU-specific

[rjc]

Case in point - #quick-tips:

$ !!
$ sudo !!
$ !<word>
$ !<word>:p

are all specific to GNU Bash and won't work on, let's say OpenBSD's ksh(1), etc. so please mark them as such.

While we're at it, if we're at "You don't need GUI", probably best to get rid of that image and replace it with plain text, eh? ;^)

Also, these examples are GNU Coreutils-specific:

$ date -d "+7 days
$ date -j -v+7d

How about sticking to POSIX-only?

[rjc]

Ping.