1. How many software packages have been installed?
[root@localhost ~]# rpm -qa | wc -l217
2. How do I know which software packages are installed?
[root@localhost ~]# rpm -qa | sortacl-2.2.49-6.el6.x86_64aic94xx-firmware-30-2.el6.noarchatmel-firmware-1.3-7.el6.noarchattr-2.4.44-7.el6.x86_64audit-2.2-2.el6.x86_64audit-libs-2.2-2.el6.x86_64authconfig-6.1.12-13.el6.x86_64b43-openfwwf-5.2-4.el6.noarchbasesystem-10.0-4.el6.noarchbash-4.1.2-15.el6_4.x86_64bfa-firmware-3.2.21.1-2.el6.noarchbinutils-2.20.51.0.2-5.36.el6.x86_64bzip2-1.0.5-7.el6_0.x86_64bzip2-libs-1.0.5-7.el6_0.x86_64ca-certificates-2013.1.94-65.0.el6.noarchcentos-release-6-5.el6.centos.11.1.x86_64checkpolicy-2.0.22-1.el6.x86_64chkconfig-1.3.49.3-2.el6_4.1.x86_64coreutils-8.4-31.el6.x86_64coreutils-libs-8.4-31.el6.x86_64cpio-2.10-11.el6_3.x86_64cracklib-2.8.16-4.el6.x86_64cracklib-dicts-2.8.16-4.el6.x86_64cronie-1.4.4-12.el6.x86_64cronie-anacron-1.4.4-12.el6.x86_64crontabs-1.10-33.el6.noarchcurl-7.19.7-37.el6_4.x86_64cyrus-sasl-2.1.23-13.el6_3.1.x86_64cyrus-sasl-lib-2.1.23-13.el6_3.1.x86_64dash-0.5.5.1-4.el6.x86_64db4-4.7.25-18.el6_4.x86_64db4-utils-4.7.25-18.el6_4.x86_64dbus-glib-0.86-6.el6.x86_64dbus-libs-1.2.24-7.el6_3.x86_64device-mapper-1.02.79-8.el6.x86_64device-mapper-event-1.02.79-8.el6.x86_64device-mapper-event-libs-1.02.79-8.el6.x86_64device-mapper-libs-1.02.79-8.el6.x86_64device-mapper-persistent-data-0.2.8-2.el6.x86_64dhclient-4.1.1-38.P1.el6.centos.x86_64dhcp-common-4.1.1-38.P1.el6.centos.x86_64diffutils-2.8.1-28.el6.x86_64dracut-004-335.el6.noarchdracut-kernel-004-335.el6.noarche2fsprogs-1.41.12-18.el6.x86_64e2fsprogs-libs-1.41.12-18.el6.x86_64efibootmgr-0.5.4-11.el6.x86_64elfutils-libelf-0.152-1.el6.x86_64ethtool-3.5-1.el6.x86_64expat-2.0.1-11.el6_2.x86_64file-5.04-15.el6.x86_64file-libs-5.04-15.el6.x86_64filesystem-2.4.30-3.el6.x86_64findutils-4.4.2-6.el6.x86_64fipscheck-1.2.0-7.el6.x86_64fipscheck-lib-1.2.0-7.el6.x86_64gamin-0.1.10-9.el6.x86_64gawk-3.1.7-10.el6.x86_64gdbm-1.8.0-36.el6.x86_64glib2-2.26.1-3.el6.x86_64glibc-2.12-1.132.el6.x86_64glibc-common-2.12-1.132.el6.x86_64gmp-4.3.1-7.el6_2.2.x86_64gnupg2-2.0.14-6.el6_4.x86_64gpgme-1.1.8-3.el6.x86_64grep-2.6.3-4.el6.x86_64groff-1.18.1.4-21.el6.x86_64grub-0.97-83.el6.x86_64grubby-7.0.15-5.el6.x86_64gzip-1.3.12-19.el6_4.x86_64hwdata-0.233-9.1.el6.noarchinfo-4.13a-8.el6.x86_64initscripts-9.03.40-2.el6.centos.x86_64iproute-2.6.32-31.el6.x86_64iptables-1.4.7-11.el6.x86_64iptables-ipv6-1.4.7-11.el6.x86_64iputils-20071127-17.el6_4.2.x86_64ipw2100-firmware-1.3-11.el6.noarchipw2200-firmware-3.1-4.el6.noarchivtv-firmware-20080701-20.2.noarchiwl1000-firmware-39.31.5.1-1.el6.noarchiwl100-firmware-39.31.5.1-1.el6.noarchiwl3945-firmware-15.32.2.9-4.el6.noarchiwl4965-firmware-228.61.2.24-2.1.el6.noarchiwl5000-firmware-8.83.5.1_1-1.el6_1.1.noarchiwl5150-firmware-8.24.2.2-1.el6.noarchiwl6000-firmware-9.221.4.1-1.el6.noarchiwl6000g2a-firmware-17.168.5.3-1.el6.noarchiwl6050-firmware-41.28.5.1-2.el6.noarchkbd-1.15-11.el6.x86_64kbd-misc-1.15-11.el6.noarchkernel-2.6.32-431.el6.x86_64kernel-firmware-2.6.32-431.el6.noarchkeyutils-libs-1.4-4.el6.x86_64krb5-libs-1.10.3-10.el6_4.6.x86_64less-436-10.el6.x86_64libacl-2.2.49-6.el6.x86_64libattr-2.4.44-7.el6.x86_64libblkid-2.17.2-12.14.el6.x86_64libcap-2.16-5.5.el6.x86_64libcap-ng-0.6.4-3.el6_0.1.x86_64libcom_err-1.41.12-18.el6.x86_64libcurl-7.19.7-37.el6_4.x86_64libdrm-2.4.45-2.el6.x86_64libertas-usb8388-firmware-5.110.22.p23-3.1.el6.noarchlibffi-3.0.5-3.2.el6.x86_64libgcc-4.4.7-4.el6.x86_64libgcrypt-1.4.5-11.el6_4.x86_64libgpg-error-1.7-4.el6.x86_64libidn-1.18-2.el6.x86_64libnih-1.0.1-7.el6.x86_64libpciaccess-0.13.1-2.el6.x86_64libselinux-2.0.94-5.3.el6_4.1.x86_64libselinux-utils-2.0.94-5.3.el6_4.1.x86_64libsemanage-2.0.43-4.2.el6.x86_64libsepol-2.0.41-4.el6.x86_64libss-1.41.12-18.el6.x86_64libssh2-1.4.2-1.el6.x86_64libstdc++-4.4.7-4.el6.x86_64libtasn1-2.3-3.el6_2.1.x86_64libudev-147-2.51.el6.x86_64libusb-0.1.12-23.el6.x86_64libuser-0.56.13-5.el6.x86_64libutempter-1.1.5-4.1.el6.x86_64libuuid-2.17.2-12.14.el6.x86_64libxml2-2.7.6-14.el6.x86_64logrotate-3.7.8-17.el6.x86_64lua-5.1.4-4.1.el6.x86_64lvm2-2.02.100-8.el6.x86_64lvm2-libs-2.02.100-8.el6.x86_64m4-1.4.13-5.el6.x86_64make-3.81-20.el6.x86_64MAKEDEV-3.24-6.el6.x86_64mingetty-1.08-5.el6.x86_64module-init-tools-3.9-21.el6_4.x86_64mysql-libs-5.1.71-1.el6.x86_64ncurses-5.7-3.20090208.el6.x86_64ncurses-base-5.7-3.20090208.el6.x86_64ncurses-libs-5.7-3.20090208.el6.x86_64net-tools-1.60-110.el6_2.x86_64newt-0.52.11-3.el6.x86_64newt-python-0.52.11-3.el6.x86_64nspr-4.10.0-1.el6.x86_64nss-3.15.1-15.el6.x86_64nss-softokn-3.14.3-9.el6.x86_64nss-softokn-freebl-3.14.3-9.el6.x86_64nss-sysinit-3.15.1-15.el6.x86_64nss-tools-3.15.1-15.el6.x86_64nss-util-3.15.1-3.el6.x86_64openldap-2.4.23-32.el6_4.1.x86_64openssh-5.3p1-94.el6.x86_64openssh-server-5.3p1-94.el6.x86_64openssl-1.0.1e-15.el6.x86_64p11-kit-0.18.5-2.el6.x86_64p11-kit-trust-0.18.5-2.el6.x86_64pam-1.1.1-17.el6.x86_64passwd-0.77-4.el6_2.2.x86_64pciutils-libs-3.1.10-2.el6.x86_64pcre-7.8-6.el6.x86_64pinentry-0.7.6-6.el6.x86_64pkgconfig-0.23-9.1.el6.x86_64plymouth-0.8.3-27.el6.centos.x86_64plymouth-core-libs-0.8.3-27.el6.centos.x86_64plymouth-scripts-0.8.3-27.el6.centos.x86_64policycoreutils-2.0.83-19.39.el6.x86_64popt-1.13-7.el6.x86_64postfix-2.6.6-2.2.el6_1.x86_64procps-3.2.8-25.el6.x86_64psmisc-22.6-15.el6_0.1.x86_64pth-2.0.7-9.3.el6.x86_64pygpgme-0.1-18.20090824bzr68.el6.x86_64python-2.6.6-51.el6.x86_64python-iniparse-0.3.1-2.1.el6.noarchpython-libs-2.6.6-51.el6.x86_64python-pycurl-7.19.0-8.el6.x86_64python-urlgrabber-3.9.1-9.el6.noarchql2100-firmware-1.19.38-3.1.el6.noarchql2200-firmware-2.02.08-3.1.el6.noarchql23xx-firmware-3.03.27-3.1.el6.noarchql2400-firmware-7.00.01-1.el6.noarchql2500-firmware-7.00.01-1.el6.noarchreadline-6.0-4.el6.x86_64redhat-logos-60.0.14-12.el6.centos.noarchrootfiles-8.1-6.1.el6.noarchrpm-4.8.0-37.el6.x86_64rpm-libs-4.8.0-37.el6.x86_64rpm-python-4.8.0-37.el6.x86_64rsyslog-5.8.10-8.el6.x86_64rt61pci-firmware-1.2-7.el6.noarchrt73usb-firmware-1.8-7.el6.noarchsed-4.2.1-10.el6.x86_64selinux-policy-3.7.19-231.el6.noarchselinux-policy-targeted-3.7.19-231.el6.noarchsetup-2.8.14-20.el6_4.1.noarchshadow-utils-4.1.4.2-13.el6.x86_64shared-mime-info-0.70-4.el6.x86_64slang-2.2.1-1.el6.x86_64sqlite-3.6.20-1.el6.x86_64sudo-1.8.6p3-12.el6.x86_64system-config-firewall-base-1.2.27-5.el6.noarchsysvinit-tools-2.87-5.dsf.el6.x86_64tar-1.23-11.el6.x86_64tcp_wrappers-libs-7.6-57.el6.x86_64tzdata-2013g-1.el6.noarchudev-147-2.51.el6.x86_64upstart-0.6.5-12.el6_4.1.x86_64ustr-1.0.4-9.1.el6.x86_64util-linux-ng-2.17.2-12.14.el6.x86_64vim-minimal-7.2.411-1.8.el6.x86_64which-2.19-6.el6.x86_64xorg-x11-drv-ati-firmware-7.1.0-3.el6.noarchxz-libs-4.999.9-0.3.beta.20091007git.el6.x86_64yum-3.2.29-40.el6.centos.noarchyum-metadata-parser-1.1.2-16.el6.x86_64yum-plugin-fastestmirror-1.1.30-14.el6.noarchzd1211-firmware-1.4-4.el6.noarchzlib-1.2.3-29.el6.x86_64