Many times, scripters will use external commands like basename, dirname and
tr  because they don't realize they can instead use ksh builtins.

An added bonus is the builtins are faster and require less system resources
because no sub-process is spawned.

basename replacement:
---------------------

$ fullfile="/some/dir/file.txt"
# replaced: file=$(basename $fullfile)
$ file=${fullfile##*/}
$ echo $file
file.txt

dirname replacement:
--------------------

$ fullfile="/some/dir/file.txt"
# replaced: dir=$(dirname $fullfile)
$ dir=${fullfile%/*}
$ echo $dir
/some/dir

tr replacements:
----------------

$ word="MiXeD"
# replaced: word=$(echo $word | tr [A-Z] [a-z])
$ typeset -l word
$ echo $word
mixed

# replaced: word=$(echo $word | tr [a-z] [A-Z])
$ typeset -u word
$ echo $word
MIXED
