mysqldump --user=$dbuser --password=$dbpswd
   --host=$host $mysqldb | gzip > $filename

VAR=$((your-command-including-redirect) 2>&1)

#!/bin/bash
BLAH=$((
(
echo out >&1
echo err >&2
) 1>log
) 2>&1)

echo "BLAH=$BLAH"

{ error=$(command 2>&1 1>&$out); } {out}>&1

{ error=$(ls /etc/passwd /etc/bad 2>&1 1>&$out); } {out}>&1 >output

result=$(mysqldump --user=$dbuser --password=$dbpswd
   --host=$host $mysqldb 3>&1 2>&3 | gzip > $filename)

$ dd if=/dev/zero count=50 > /dev/null
50+0 records in
50+0 records out

$ dd if=/dev/zero count=50 2> countfile | wc -c
25600
$ cat countfile
50+0 records in
50+0 records out
$ mail -s "countfile for you" thornate < countfile

$ variable=`cat countfile`