Differences between Centos 6.X and Centos 7.x

Man:

Centos 6.x

[Root @ Lnmp ~] # Whatis man
Man: nothing appropriate
[Root @ Lnmp ~] # Makewhatis
[Root @ Lnmp ~] # Man-f man
Man (1)-format and display the on-line manual pages
Man. config [man] (5)-configuration data for man
Man [manpath] (1)-format and display the on-line manual pages
Centos 7.x

[Root @ localhost ~] # Man-f man
Man: nothing appropriate.
[Root @ localhost ~] # Makewhatis
-Bash: makewhatis: command not found
[Root @ localhost ~] # Mandb
[Root @ localhost ~] # Man-f man
Man (1)-an interface to the on-line reference manuals

Service Startup:

Centos6.x:

[Root @ Shell byrd] #/etc/init. d/sshd status # query the sshd service status
Openssh-daemon (pid 1183) is running...
[Root @ Shell byrd] #/etc/init. d/sshd restart # restart the sshd service
Stopping sshd: [OK]
Starting sshd: [OK]
[Root @ Shell byrd] # service sshd restart # restart the sshd service
[Root @ Shell byrd] # chkconfig -- list | grep 3: on # start the service

Centos7.x:

[Root @ hz ~] # Systemctl status sshd. service # query the sshd service status
Sshd. service-OpenSSH server daemon
Loaded: loaded (/usr/lib/systemd/system/sshd. service; enabled)
Active: active (running) since Tue 2016-01-12 16:04:22 CST; 5 min ago
Process: 2018 ExecStartPre =/usr/sbin/sshd-keygen (code = exited, status = 0/SUCCESS)
Main PID: 2019 (sshd)
CGroup:/system. slice/sshd. service
2017-20/2019/usr/sbin/sshd-D
[Root @ hz ~] # Systemctl restart sshd. service # restart the sshd service
[Root @ hz ~] # Systemctl list-unit-files | grep enabled # Query all startup services

Firewall

Centos6.x (iptables by default ):

[Root @ Shell byrd] # iptables-t filter-a input-p tcp -- dport 22-j ACCEPT # port 22 is allowed. The default sshd service

Centos7.x (firewalld by default ):

[Root @ hz ~] # Firewall-cmd -- permanent -- zone = public -- add-port = 22/tcp # port 22 is allowed. The sshd service is used by default.
Not finished yet !!!