Escaping a lengthy Bash command to use with PHP exec() - php

Question

I have a semi-lengthy shell command that I need to execute from within php. I feel like I have everything properly escaped, however it is not working properly when executed from php's exec() function. When I run the command with exec() it exits without error, but does not run properly.
I am comparing a list file that has email addresses with additional pipe delimited information against a text file containing the md5 version of email addresses to suppress from the original list.
Here is the bash command:
while read line ; do email=`echo "$line" | cut -d '|' -f1` ; if [ $(E=`echo -en "$email" | md5sum | awk '{print $1}'`; grep $E /path/to/suppressions | head -1 ;) ] ; then continue ; else echo $line ; fi done < /path/to/emails
/path/to/suppressions is a text file, containing the md5 version of an email address to suppress (it contains the md5 for "emailtosuppress#domain.com":
edb5feb3be7d0a4e1e250ccdf0c04ace
/path/to/emails is a text file containing a list of email addresses with some other delimeted information:
emailtokeep#domain.com|1000|1
emailtosuppress#domain.com|1000|1
When the command is executed in bash, the output is simply the email address that does NOT exist in the suppression list, and it works flawless:
emailtokeep#domain.com|1000|1
The trouble I am having is when I execute this same command with exec() in php, it outputs all the lines from the "emails" file, without suppressing any matches from the suppression file.
$supCommand = 'while read line ; do email=`echo "$line" | cut -d \'|\' -f1` ; if [ $(E=`echo -en "$email" | md5sum | awk \'{print $1}\'`; grep $E /path/to/suppressions | head -1 ;) ] ; then continue ; else echo $line ; fi done < /path/to/emails' ;
exec($supCommand, $supStatus) ;
print_r($supStatus) ;
I enclosed the command in single quotes, and escaped the four instances of single quotes within the command. If anyone has any ideas I would be extremely GRATEFUL.
Thanks in advance :)

Answer 1

This seems to work:
<?php
$bash = '
mapfile -t md5sums < suppressions
function md5 { printf "%s" "$1" | md5sum | cut -f1 -d" "; }
while IFS="|" read -r email b c; do
this_md5=$(md5 "$email")
for suppress in "${md5sums[#]}"; do
[[ $this_md5 == $suppress ]] && continue 2
done
echo "$email|$b|$c"
done < emails
';
$cmd = "bash -c '$bash'";
$keep = passthru($cmd);
print($keep);
?>