Finding the least binary logs amount multiple slaves connected in master

I have the master server with multiple slaves (for ex: 4). I would like to purge the binary logs after checking the processed binlogs on all slaves. I wrote the below script to find the least binlogs (last second binarylogs) to purge.

#!/bin/bash
set -x
binlogval=""

Find the ip address

for i in $(mysql -u$user -p$pw  -e "show processlist" | egrep -i "Binlog Dump" | awk 'BEGIN{FS="\t"} {print $3}' | cut -d ':' -f1);
     do echo "$i"; 
     #shost=`echo IP$i| tr '.' '_'`;

Find the Relay_Master_Log_File on slave side

binlogv=`/usr/local/mysql/bin/mysql -u$user -p$pw -h $i  -sss -e "show slave status\G" | grep "Relay_Master_Log_File:" | awk -F"." '{print $2}'`;
binlogval="$binlogval:$binlogv";
done;
lowestvalue=`echo $binlogval | tr ':' '\n' | grep ^[0-9] | sort -n | head -1` 

Find the value of the lest binary log

safe_binlog="mysql-bin."$lowestvalue

Find the last second of the least binary logs for purging (safe)

last_binlog=`echo "$safe_binlog" | awk -F"." '{ res=$2 - 1 ; difflen=length($2) - length(res); if(difflen > 0){for(i=1;i<=difflen;i++){str=str 0}}print $1 "." str res}'`

Script to purge the binary logs from master server

echo $last_binlog

Here, if the mysql is placed in different socket, I can't access the mysql.

In simple terms, if the socket files placed it in different location for one instance, and by this script it throws error.

So, I would like to get the below values for the slaves.

1. IP address - that has been taken already
2. Port/hostname of the slave - How to find the slave socket from the master ( In case the report_xxxx is not configured)

3. socket of the running mysql - How to find the slave socket from the master server.

   mysql -u$user -u$port -p -P$port -S$socket - that will work for me.  But I don't think we can find from master server.
   

Is there any approach to find the least binary logs?