Fix corrupted RPM database on CentOS 5 / Redhat enterprise Linux 5 / Fedora 7

If rpm / yum command hangs during operations or you see error messages - it means your rpm database corrupted. /var/lib/rpm/ stores rpm database just delete the same and rebuild rpm database:
Command to rebuild rpm database
rm -f /var/lib/rpm/__db*
rpm --rebuilddb
Rebuilding corrupted RPM database
One of our client reported that he is getting an error and RPM database is corrupted. He is using Red Hat Linux
Sometime it is possible to fix RPM database errors. I am surprised that many admins do not make back up of RPM DB (/var/lib/rpm).
Anyways if you ever messed up with RPM database, here is a quick guide to fix it (you must have rpmdb tools installed):
Take system to single user mode to avoid further damage and to make backup/restore process easy:
# init 1
Method # 1
Remove /var/lib/rpm/__db* files to avoid stale locks:
# cd /var/lib
# rm __db*
Rebuild RPM database:
# rpm --rebuilddb
# rpmdb_verify Packages
Method # 2
If you are still getting errors, then try your luck with following commands:
# mv Packages Packages-BAKUP
# db_dump Packages-BAKUP | db_load Packages
# rpm -qa
# rpm --rebuilddb
Segmentation Fault Occur on Linux

Usually signal #11 (SIGSEGV) set, which is defined in the header file signal.h file. The default action for a program upon receiving SIGSEGV is abnormal termination. This action will end the process, but may generate a core file (also known as core dump) to aid debugging, or perform some other platform-dependent action. A core dump is the recorded state of the working memory of a computer program at a specific time, generally when the program has terminated abnormally.
Segmentation fault can also occur under following circumstances:
a) A buggy program / command, which can be only fixed by applying patch.
b) It can also appear when you try to access an array beyond the end of an array under C programming.
c) Inside a chrooted jail this can occur when critical shared libs, config file or /dev/ entry missing.
d) Sometime hardware or faulty memory or driver can also create problem.
e) Maintain suggested environment for all computer equipment (overheating can also generate this problem).