The best way to explain this is with an example:
You may want to write a simple script that launches an xterm window with different color
options. Pseudo hash tables in bourne shell.
$ xwindow MidnightBlue
An easy way to this is by first listing the supported colors in the script (pseudo hash table):
Next, simply grab the hex color code by using the following command:
BGColor=`eval echo $"$(echo $1)"`
"$(echo $1)" evaluates to "MidnightBlue" and
`eval echo $MidnightBlue evaluates to "#191970".
Simply launch the xterm window using $BGColor as the background color:
xterm -bg="$BGColor" &
This method for extracting pseudo hash values may be used for NIS map files, file date stamps, GUI colors, etc.