Comment 1 for bug 1725927

Verified on 5.6.37-rel82.2.el7. 5.7 is not affected.

mysqladmin is trying to read file ~/my.cnf:
    stat("~/.my.cnf", 0x7ffe1f11bcd0) = -1 ENOENT (No such file or directory)

however, SystemD sets $HOME environment variable only if User directive is set in systemd service.

It can be fixed with adding User=root directive to /etc/systemd/system/mysql.service file.

#
# Systemd service file for Percona Server
#
# # This service file is to start PS just with mysqld_safe
#

[Unit]
User=root
Description=MySQL Percona Server
After=network.target
After=syslog.target

[Install]
WantedBy=multi-user.target
Alias=mysql.service

[Service]
# Needed to create system tables etc.
ExecStartPre=/usr/bin/mysql-systemd pre

# Start main service
ExecStart=/usr/bin/mysqld_safe

# Don't signal startup success before a ping works
ExecStartPost=/usr/bin/mysql-systemd post

# Give up if ping don't get an answer
TimeoutSec=600

Restart=always
PrivateTmp=false