how simple it is

echo `< /dev/urandom tr -dc A-Za-z0-9 | head -c 10`

Read further for complicated edition.

Usage : apg.sh 10 (generate 10 character password)

| apg.sh

#!/bin/bash
if [ $# -lt 1 ]; then
echo "Usage : apg <lenght of password>"
else
for ((n=0;n<10;n++)); do dd if=/dev/urandom count=1 2> /dev/null | /usr/bin/gmime-uuencode -m -| sed -ne 2p | cut -c-$1; done
fi

| apg

#!/bin/bash
if [ $# -gt 2 ]; then
echo "Usage : $0 [<Number Of Password>] [<Lenght Of Password>]"
else
if [ $1 ]; then
        itr=$1
else
	itr='10'
fi
if [ $2 ]; then
	len=$2
else
        len='15'
fi
for ((n=0;n<$itr;n++)); do dd if=/dev/urandom count=1 2> /dev/null | /usr/bin/gmimeuuencode -m -| sed -ne 2p | cut -c-$len; done
fi