sudo su

Download NMON archive

cd /tmp

wget http://nmon.sourceforge.net/docs/MPG_nmon_for_Linux_14a_binaries.zip

Install unzip if you don’t have

yum install unzip

Unzip archive

unzip MPG_nmon_for_Linux_14a_binaries.zip

Copy nmon file

cp nmon_x86_64_centos5 /usr/local/bin/

chmod a+x /usr/local/bin/nmon_x86_64_centos5

Create symbolic link

ln -s /usr/local/bin/nmon_x86_64_centos5 /usr/local/bin/nmon