any2any.sh

#! /bin/bash
#
# A generalised converter to convert all files of
# a given extension in a directory to another
# type.
#
# I simply assume that yourConverter can detect
# the input files' type, and figure out the
# destination type from $ext_out

ext_in=doc
ext_out=txt

# Set the input field separator to newline only.
# This is required if you have at least one file
# with a space in its name.
IFS='
'
for i in `ls -1 *.$ext_in`
do
    o="${i%$ext_in}$ext_out"
    yourConverter -i "$i" -o "$o"
done