Failsafe home dir obtaining
Failsafe home dir obtaining

+ When estimating $INSTALL_HOME, assure grep can only match user names, to avoid possible wrong multi-line value
+ Remove possible trailing slash from $INSTALL_HOME, to avoid double slash in "$INSTALL_HOME/ovpns"
+ Avoid "cat <file> | grep <pattern>", since grep can process files directly

Signed-off-by: MichaIng <5f726662e7ca541c0aec63efdec81c7c2711727a@dietpi.com>
pivpn/pivpn