8 Essential RHEL7 Changes Every Sysadmin Should Master

Part.1 System Service Management Changes

RHEL6 used service and chkconfig to manage SysVinit services. In RHEL7 these commands manage only a few legacy services; most services are managed by systemd using systemctl. For example, the Apache service commands differ as follows:

Purpose

RHEL6

RHEL7

Start service

service httpd start

systemctl start httpd

(or httpd.service)

Stop service

service httpd stop

systemctl stop httpd

Check status

service httpd status

systemctl status httpd

Restart service

service httpd restart

systemctl restart httpd

Check enable status

chkconfig --list httpd

systemctl is-enabled httpd

Enable at boot

chkconfig httpd on

systemctl enable httpd

Disable at boot

chkconfig httpd off

systemctl disable httpd

Part.2 Custom Scripts in /etc/rc.local

In RHEL6 custom scripts placed in /etc/rc.local ran automatically at boot. RHEL7 keeps /etc/rc.local only for compatibility and disables it by default. To enable, run chmod +x /etc/rc.d/rc.local. Note that /etc/rc.local is a symlink to /etc/rc.d/rc.local, which has different permissions.

Part.3 Automatic File Cleanup Changes

RHEL6 used tmpwatch (configured in /etc/cron.daily/tmpwatch) to clean /tmp and /var/tmp. RHEL7 relies on systemd-tmpfiles-clean.service, with its timer at /usr/lib/systemd/system/systemd-tmpfiles-clean.timer and cleanup rules in /usr/lib/tmpfiles.d/tmp.conf. Important files should be stored outside the automatically cleaned directories.

Part.4 Time Synchronization Changes (timedatectl)

RHEL6 used NTP with /etc/ntp.conf and the ntpd service. RHEL7 switches to chrony (config file /etc/chrony.conf) while still supporting ntpdate. The new timedatectl command provides powerful time management, e.g.: timedatectl (or timedatectl status)

Show date, time and sync status timedatectl set-time "2019-07-01 12:00:00" Set system clock timedatectl list-timezones List available time zones timedatectl set-timezone Asia/Shanghai Configure time zone timedatectl set-ntp true Enable time synchronization service timedatectl set-local-rtc 0 Set hardware clock to UTC

Part.5 Hostname Modification Changes

RHEL6 required editing /etc/sysconfig/network after using hostname. RHEL7 introduces hostnamectl, which changes the hostname instantly and persists across reboots. It also supports graphical tools nmtui and nmtui-hostname. Hostnames can be static, pretty, or transient.

Part.6 MySQL Deployment on RHEL7

RHEL6 provided mysql-server via yum. RHEL7 defaults to MariaDB; install with yum install mariadb-server. MariaDB is a drop‑in replacement for MySQL, fully compatible.

Part.7 Network Interface Configuration Changes

RHEL6 used system-config-network or setup for GUI editing. RHEL7 replaces these with nmcli (CLI) and nmtui (TUI). The traditional ifconfig and route commands are deprecated in favor of ip addr and ip route.

Part.8 Log System Upgrade

RHEL6 used rsyslog. RHEL7 adds systemd-journald alongside rsyslog. The journalctl command provides powerful log queries, e.g.:

Show last 20 lines journalctl -n 20 Show logs of PID 1 journalctl _PID=1 Show ssh service logs journalctl _COMM=sshd Show logs from previous boot journalctl -b -1 Show error level logs journalctl -p err Show yesterday's logs journalctl --since yesterday Show logs in a time range

journalctl --since 9:00 --until 18:00

Summary

Beyond the eight topics covered, RHEL7 also introduces other features such as firewalld replacing iptables. The core upgrade is the adoption of systemd for service management, along with new utilities like loginctl and coredumpctl for user sessions and crash analysis.