Bash Redirection not Working in Shell Scripts + Solution

I recently needed to trigger a couple of bash scripts through a web browser.

Unfortunately PHP shell_exec function grinds to a halt when it is used to trigger a long running / memory intensive script when it is used with Apache.

To get round this I instead wrote the command to a file and then wanted to trigger it using cron.

However, the commands that were being issues included a redirect and disown which were not being triggered in the following script

#!/bin/bash
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
COMMAND=`cat ${DIR}/commandFile | tail -n 1`;
#Check the command
echo ${COMMAND};
# Command is /path/to/file.sh arg1 > /path/to/outputFile & disown
#Run the command
${TEST}

After having a play around I found that modifying the file to this will redirect the output and then disown the process

#!/bin/bash
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
COMMAND=`cat ${DIR}/commandFile | tail -n 1`;
#Check the command
echo ${COMMAND};
# Command is /path/to/file.sh arg1 > /path/to/outputFile & disown
#Run the command - This line has been changed
eval ${TEST}