Elastic Search not update config (elasticsearch.yml)

Elastic Stack Elasticsearch
10

$ES_PATH_CONF is empty.

icluster@icluster-node-d000:~$ echo $ES_PATH_CONF

icluster@icluster-node-d000:~$ ls -l /etc/sysconfig/elasticsearch
ls: cannot access '/etc/sysconfig/elasticsearch': No such file or directory
icluster@icluster-node-d000:~$ cat /etc/sysconfig/elasticsearch
cat: /etc/sysconfig/elasticsearch: No such file or directory
icluster@icluster-node-d000:~$ ls -l /etc/default/elasticsearch
-rw-rw---- 1 root elasticsearch 1613 Aug 29 19:15 /etc/default/elasticsearch
icluster@icluster-node-d000:~$ cat /etc/default/elasticsearch
cat: /etc/default/elasticsearch: Permission denied
icluster@icluster-node-d000:~$ sudo cat /etc/default/elasticsearch
################################
# Elasticsearch
################################

# Elasticsearch home directory
#ES_HOME=/usr/share/elasticsearch

# Elasticsearch Java path
#JAVA_HOME=

# Elasticsearch configuration directory
ES_PATH_CONF=/etc/elasticsearch

# Elasticsearch PID directory
#PID_DIR=/var/run/elasticsearch

# Additional Java OPTS
#ES_JAVA_OPTS=

# Configure restart on package upgrade (true, every other setting will lead to not restarting)
#RESTART_ON_UPGRADE=true

################################
# Elasticsearch service
################################

# SysV init.d
#
# The number of seconds to wait before checking if Elasticsearch started successfully as a daemon process
ES_STARTUP_SLEEP_TIME=5

################################
# System properties
################################

# Specifies the maximum file descriptor number that can be opened by this process
# When using Systemd, this setting is ignored and the LimitNOFILE defined in
# /usr/lib/systemd/system/elasticsearch.service takes precedence
#MAX_OPEN_FILES=65535

# The maximum number of bytes of memory that may be locked into RAM
# Set to "unlimited" if you use the 'bootstrap.memory_lock: true' option
# in elasticsearch.yml.
# When using systemd, LimitMEMLOCK must be set in a unit file such as
# /etc/systemd/system/elasticsearch.service.d/override.conf.
#MAX_LOCKED_MEMORY=unlimited

# Maximum number of VMA (Virtual Memory Areas) a process can own
# When using Systemd, this setting is ignored and the 'vm.max_map_count'
# property is set at boot time in /usr/lib/sysctl.d/elasticsearch.conf
#MAX_MAP_COUNT=262144