原来是系统中设置了DISPLAY环境变量,执行：

[oracle@qa26 database]$ ./runInstaller -silent -responseFile /usr/local/oracle/response/db_install.rsp -ignorePrereq
正在启动 Oracle Universal Installer...


检查临时空间: 必须大于 120 MB。 实际为 34078 MB 通过
检查交换空间: 必须大于 150 MB。 实际为 3951 MB 通过
准备从以下地址启动 Oracle Universal Installer /tmp/OraInstall2017-04-20_03-14-19PM. 请稍候...[oracle@qa26 database]$ Exception in thread "main" java.lang.NoClassDefFoundError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at java.awt.Toolkit$2.run(Toolkit.java:821)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Toolkit.getDefaultToolkit(Toolkit.java:804)
at javax.swing.UIManager.initialize(UIManager.java:1262)
at javax.swing.UIManager.maybeInitialize(UIManager.java:1245)
at javax.swing.UIManager.getUI(UIManager.java:851)
at javax.swing.JPanel.updateUI(JPanel.java:104)
at javax.swing.JPanel.<init>(JPanel.java:64)
at javax.swing.JPanel.<init>(JPanel.java:87)
at javax.swing.JPanel.<init>(JPanel.java:95)
at oracle.sysman.oii.oiif.oiifo.OiifoOCMUI.<init>(OiifoOCMUI.java:125)
at oracle.sysman.oii.oiif.oiifo.OiifoOCMInterfaceManager.<init>(OiifoOCMInterfaceManager.java:79)
at oracle.sysman.oii.oiif.oiifo.OiifoOCMInterfaceManager.getInstance(OiifoOCMInterfaceManager.java:124)
at oracle.install.ivw.db.driver.DBInstaller.run(DBInstaller.java:123)
at oracle.install.commons.util.Application.startup(Application.java:869)
at oracle.install.commons.flow.FlowApplication.startup(FlowApplication.java:164)
at oracle.install.commons.flow.FlowApplication.startup(FlowApplication.java:181)
at oracle.install.commons.base.driver.common.Installer.startup(Installer.java:265)
at oracle.install.ivw.db.driver.DBInstaller.startup(DBInstaller.java:114)
at oracle.install.ivw.db.driver.DBInstaller.main(DBInstaller.java:132)

原来是系统中设置了DISPLAY环境变量

执行：

unset DISPLAY

然后再执行runInstaller.sh，执行成功