CentOS7最小化安裝後預設yum會自動下載更新，這對許多生產系統是不需要的，可以手動關閉它

[[email protected] cron.weekly]# cd /etc/yum
[[email protected] yum]# ls
fssnap.d  pluginconf.d  protected.d  vars  version-groups.conf  yum-cron.conf  yum-cron-hourly.conf

編輯yum-cron.conf，將download_updates = yes改為no即可

[[email protected] yum]# cat yum-cron.conf 
[commands]
#  What kind of update to use:
# default                            = yum upgrade
# security                           = yum --security upgrade
# security-severity:Critical         = yum --sec-severity=Critical upgrade
# minimal                            = yum --bugfix upgrade-minimal
# minimal-security                   = yum --security upgrade-minimal
# minimal-security-severity:Critical =  --sec-severity=Critical upgrade-minimal
update_cmd = default


# Whether a message should be emitted when updates are available,
# were downloaded, or applied.
update_messages = yes


# Whether updates should be downloaded when they are available.
download_updates = yes


# Whether updates should be applied when they are available.  Note
# that download_updates must also be yes for the update to be applied.
apply_updates = no


# Maximum amout of time to randomly sleep, in minutes.  The program
# will sleep for a random amount of time between 0 and random_sleep
# minutes before running.  This is useful for e.g. staggering the
# times that multiple systems will access update servers.  If
# random_sleep is 0 or negative, the program will run immediately.
# 6*60 = 360
random_sleep = 360




[emitters]
# Name to use for this system in messages that are emitted.  If
# system_name is None, the hostname will be used.
system_name = None


# How to send messages.  Valid options are stdio and email.  If
# emit_via includes stdio, messages will be sent to stdout; this is useful
# to have cron send the messages.  If emit_via includes email, this
# program will send email itself according to the configured options.
# If emit_via is None or left blank, no messages will be sent.
emit_via = stdio


# The width, in characters, that messages that are emitted should be
# formatted to.
ouput_width = 80




[email]
# The address to send email messages from.
email_from =

[email protected]


# List of addresses to send messages to.
email_to = root


# Name of the host to connect to to send email messages.
email_host = localhost




[groups]
# NOTE: This only works when group_command != objects, which is now the default
# List of groups to update
group_list = None


# The types of group packages to install
group_package_types = mandatory, default


[base]
# This section overrides yum.conf


# Use this to filter Yum core messages
# -4: critical
# -3: critical+errors
# -2: critical+errors+warnings (default)
debuglevel = -2


# skip_broken = True
mdpolicy = group:main


# Uncomment to auto-import new gpg keys (dangerous)
# assumeyes = True