lm_sensors stands for “Linux-monitoring sensors” and is an open source tool to display CPU temperature as well as other sensors such as voltage and fan speed.  In most instances, it is used to display CPU temperature as many of the mid to low-end servers do not provide fan or voltage sensors, or they are supported via IPMI (Intelligent Platform Management Interface) . Often the lm_sensors software does not include proper IPMI support.

Installation and configuration of lm_sensors is straight forward using yum:

sudo yum install lm_sensors

Once the software is installed you must configure the sensors.  Run the sensors-detect to configure the sensors:

sudo sensors-detect

Once the detection routine is running respond with yes (Y) the following question:

Some south bridges, CPUs or memory controllers contain embedded sensors.
Do you want to scan for them? This is totally safe. (YES/no):

In the example below after scanning for different sensors,  the Intel® thermal sensor was found as the example server has an Intel® Xeon® CPU.

Some south bridges, CPUs or memory controllers contain embedded sensors.
Do you want to scan for them? This is totally safe. (YES/no): y
Silicon Integrated Systems SIS5595... No
VIA VT82C686 Integrated Sensors... No
VIA VT8231 Integrated Sensors... No
AMD K8 thermal sensors... No
AMD Family 10h thermal sensors... No
AMD Family 11h thermal sensors... No
AMD Family 12h and 14h thermal sensors... No
AMD Family 15h thermal sensors... No
AMD Family 16h thermal sensors... No
AMD Family 17h thermal sensors... No
AMD Family 15h power sensors... No
AMD Family 16h power sensors... No
Intel digital thermal sensor... Success!
(driver `coretemp')
Intel AMB FB-DIMM thermal sensor... No
Intel 5500/5520/X58 thermal sensor... No
VIA C7 thermal sensor... No
VIA Nano thermal sensor... No

Next respond with yes the next several questions.  Finally when everything is complete, you can simply type the sensors command.

[user@testserver ~]$sensors
coretemp-isa-0001
Adapter: ISA adapter
Core 0: +47.0°C (high = +80.0°C, crit = +90.0°C)
Core 1: +47.0°C (high = +80.0°C, crit = +90.0°C)
Core 2: +44.0°C (high = +80.0°C, crit = +90.0°C)
Core 3: +44.0°C (high = +80.0°C, crit = +90.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Core 0: +41.0°C (high = +80.0°C, crit = +90.0°C)
Core 1: +36.0°C (high = +80.0°C, crit = +90.0°C)
Core 2: +39.0°C (high = +80.0°C, crit = +90.0°C)
Core 3: +35.0°C (high = +80.0°C, crit = +90.0°C)

Cheers!