RPM Installation Errors
Sometimes the installation of RPM software doesn't go according to plan and you need to take corrective actions. This section shows you how to recover from some of the most common errors you'll encounter.
Failed Dependencies
Sometimes RPM installations will fail, giving Failed dependencies errors, which really means that a prerequisite RPM needs to be installed. In the next example we're attempting to install the MySQL database server application, which fails because the mysql MySQL client RPM, on which it depends, needs to be installed beforehand:
[root@bigboy tmp]# rpm -Uvh mysql-server-3.23.58-9.i386.rpm
error: Failed dependencies:
libmysqlclient.so.10 is needed by mysql-server-3.23.58-9
mysql = 3.23.58 is needed by mysql-server-3.23.58-9
[root@bigboy tmp]#
Installing the MySQL client also fails because it requires the perl-DBD-MySQL package:
[root@bigboy tmp]# rpm -Uvh mysql-3.23.58-9.i386.rpm
error: Failed dependencies:
perl-DBD-MySQL is needed by mysql-3.23.58-9
[root@bigboy tmp]# rpm -Uvh perl-DBD-MySQL-2.9003-4.i386.rpm
error: Failed dependencies:
libmysqlclient.so.10 is needed by perl-DBD-MySQL-2.9003-4
[root@bigboy tmp]#
Strangely enough, the installation of the perl-DBD-MySQL package fails because it needs the mysql client package. To get around this problem you can run the rpm command with the --nodeps option to disable dependency checks. In the next example we install the MySQL client ignoring dependencies, followed by successful installation of perl-DBD-MySQL and mysql-server:
[root@bigboy tmp]# rpm -Uvh --nodeps mysql-3.23.58-9.i386.rpm
Preparing... ####################### [100%]
1:mysql ####################### [100%]
[root@bigboy tmp]# rpm -Uvh perl-DBD-MySQL-2.9003-4.i386.rpm
Preparing... ####################### [100%]
1:perl-DBD-MySQL ####################### [100%]
[root@bigboy tmp]# rpm -Uvh mysql-server-3.23.58-9.i386.rpm
Preparing... ####################### [100%]
1:mysql-server ####################### [100%]
[root@bigboy tmp]#
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If all the installation RPMs are located in the same directory, the rpm command can automatically install all the prerequisite RPMs using the --aid option. One of the advantages of using the yum facility is that you don't have to worry about this dependency process as much because the dependency RPMs are always downloaded and installed automatically also.
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Signature Keys
Fedora digitally signs all its RPM files, so it's best to import their public encryption key beforehand so that the RPM installation program will be able to verify the validity of the RPM file. This can be done using the rpm command as seen in the next example. It is a good idea to import both the Red Hat and Fedora keys:
[root@bigboy tmp]# rpm --import /usr/share/rhn/RPM-GPG-KEY
[root@bigboy tmp]# rpm --import /usr/share/rhn/RPM-GPG-KEY-fedora
[root@bigboy tmp]#
If you don't install the keys you get a DSA signature warning that alerts you to the fact that the RPM file might be bogus:
[root@bigboy tmp]# rpm -Uvh dhcp-3.0pl2-6.16.i386.rpm
warning: dhcp-3.0pl2-6.16.i386.rpm: V3 DSA signature: NOKEY, key ID
4f2a6fd2
Preparing... #################################### [100%]
1:dhcp #################################### [100%]
[root@bigboy tmp]#
It is always good to install the key files. If they are not there, the RPMs will install with only a warning message. If the RPM's digital signature doesn't match that in the key file, the rpm installation program also alerts you and fails to install the RPM package at all:
[root@bigboy tmp]# rpm -Uvh dhcp-3.0pl2-6.16.i386.rpm
error: dhcp-3.0pl2-6.16.i386.rpm: V3 DSA signature: BAD, key ID
4f2a6fd2
error: dhcp-3.0pl2-6.16.i386.rpm cannot be installed
[root@bigboy tmp]#
Signatures are therefore useful because they help protect you against tampered and otherwise corrupted RPMs being installed.
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