Request a dummy image from http://dummyimage.com from within your shell session. MIT license.

dummyimg.sh

#!/bin/bash
# (C) 2012 Manuel Strehl
#
# Published under the MIT license <http://opensource.org/licenses/mit-license>.

if [ "$1" = "-h" -o "$1" = "--help" ]; then
  cat <<USAGE
usage: $(basename $0) WIDTH [HEIGHT]

Request a dummy image from <http://dummyimage.com>. If HEIGHT is omitted, it
is set to WIDTH. You can specify a custom text by piping it to $(basename $0):

    $ echo 'Hello World!' | $(basename $0) 500

The image is stored as {WIDTH}x{HEIGHT}.png. You can alter the location by
redirecting the output:

    $ $(basename $0) 500 > myname.png
USAGE
  exit
fi

w=$1
h=${2-$1}
target="$(pwd)/${w}x${h}.png"
text=

if [ ! -t 0 ]; then
  read text
  text="$(perl -MURI::Escape -e 'print uri_escape($ARGV[0]);' "$text")"
fi

if [ ! -t 1 ]; then
  target=-
fi

wget -O "$target" http://dummyimage.com/${w}x${h}/146991/c2dfed.png?text="$text"