In its simplest form, RPM can be used to install packages:
rpm -i foobar-1.0-1.i386.rpm
rpm -e foobar
One of the more complex but highly useful commands allows you to install packages via FTP. If you are connected to the net and want to install a new package, all you need to do is specify the file with a valid URL, like so:
rpm -i ftp://ftp.pht.com/pub/linux/redhat/rh-2.0-beta/RPMS/foobar-1.0-1.i386.rpm
Please note, that RPM will now query and/or install via FTP.
While these are simple commands, rpm can be used in a multitude
of ways as seen from the Usage message:
RPM version 2.3.9
Copyright (C) 1997 - Red Hat Software
This may be freely redistributed under the terms of the GNU Public License
usage: rpm {--help}
rpm {--version}
rpm {--initdb} [--dbpath <dir>]
rpm {--install -i} [-v] [--hash -h] [--percent] [--force] [--test]
[--replacepkgs] [--replacefiles] [--root <dir>]
[--excludedocs] [--includedocs] [--noscripts]
[--rcfile <file>] [--ignorearch] [--dbpath <dir>]
[--prefix <dir>] [--ignoreos] [--nodeps]
[--ftpproxy <host>] [--ftpport <port>]
file1.rpm ... fileN.rpm
rpm {--upgrade -U} [-v] [--hash -h] [--percent] [--force] [--test]
[--oldpackage] [--root <dir>] [--noscripts]
[--excludedocs] [--includedocs] [--rcfile <file>]
[--ignorearch] [--dbpath <dir>] [--prefix <dir>]
[--ftpproxy <host>] [--ftpport <port>]
[--ignoreos] [--nodeps] file1.rpm ... fileN.rpm
rpm {--query -q} [-afpg] [-i] [-l] [-s] [-d] [-c] [-v] [-R]
[--scripts] [--root <dir>] [--rcfile <file>]
[--whatprovides] [--whatrequires] [--requires]
[--ftpuseport] [--ftpproxy <host>] [--ftpport <port>]
[--provides] [--dump] [--dbpath <dir>] [targets]
rpm {--verify -V -y} [-afpg] [--root <dir>] [--rcfile <file>]
[--dbpath <dir>] [--nodeps] [--nofiles] [--noscripts]
[--nomd5] [targets]
rpm {--setperms} [-afpg] [target]
rpm {--setugids} [-afpg] [target]
rpm {--erase -e} [--root <dir>] [--noscripts] [--rcfile <file>]
[--dbpath <dir>] [--nodeps] [--allmatches]
package1 ... packageN
rpm {-b|t}[plciba] [-v] [--short-circuit] [--clean] [--rcfile <file>]
[--sign] [--test] [--timecheck <s>] specfile
rpm {--rebuild} [--rcfile <file>] [-v] source1.rpm ... sourceN.rpm
rpm {--recompile} [--rcfile <file>] [-v] source1.rpm ... sourceN.rpm
rpm {--resign} [--rcfile <file>] package1 package2 ... packageN
rpm {--addsign} [--rcfile <file>] package1 package2 ... packageN
rpm {--checksig -K} [--nopgp] [--nomd5] [--rcfile <file>]
package1 ... packageN
rpm {--rebuilddb} [--rcfile <file>] [--dbpath <dir>]
rpm {--querytags}
You can find more details on what those options do in the RPM man page.