Para listar todos os pacotes instalados, você pode usar:
# yum list installed
Para um pacote específico, tente isto:
# yum info httpd
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.vietoss.com
* epel: ftp.cuhk.edu.hk
* extras: mirror.vietoss.com
* rpmforge: ftp-stud.fht-esslingen.de
* updates: mirror.vietoss.com
Installed Packages
Name : httpd
Arch : x86_64
Version : 2.2.3
Release : 43.el5.centos
Size : 3.3 M
Repo : installed
Summary : Apache HTTP Server
URL : http://httpd.apache.org/
License : Apache Software License
Description: The Apache HTTP Server is a powerful, efficient, and extensible
: web server.
Available Packages
Name : httpd
Arch : x86_64
Version : 2.2.3
Release : 53.el5.centos.3
Size : 1.2 M
Repo : updates
Summary : Apache HTTP Server
URL : http://httpd.apache.org/
License : Apache Software License
Description: The Apache HTTP Server is a powerful, efficient, and extensible
: web server.
# yum list httpd
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.vietoss.com
* epel: ftp.cuhk.edu.hk
* extras: mirror.vietoss.com
* rpmforge: ftp-stud.fht-esslingen.de
* updates: mirror.vietoss.com
Installed Packages
httpd.x86_64 2.2.3-43.el5.centos installed
Available Packages
httpd.x86_64 2.2.3-53.el5.centos.3 updates