What do you do when a collegue has deleted the rpm and yum packages from a CentOS system (by mocking around with the sqlite package)? Reinstall them of course. Hmm but how, when rpm is absent?
Setting up a local rpm installation
The solution is to copy rpm from another computer with (approximately) the same operating system. The following files are required (substitute lib64 for lib when you're on a 32-bit system), put them in a temporary directory on the target system:
- /bin/rpm --> bin/
- /usr/lib64/librpm*.so --> lib/
- /usr/lib64/libsqlite*.so --> lib/
- /usr/lib/rpm/macros --> lib/rpm
Some configuration files are expected to be present, though, and rpm needs to be told to look for them in the correct location. This is done with a little wrapper script (named rpm.sh) like this:
#!/bin/sh
export LD_LIBRARY_PATH=`dirname $0`/lib
mv ~/.rpmmacros ~/.rpmmacros.orig
cp `dirname $0`/lib/rpm/macros ~/.rpmmacros
`dirname $0`/bin/rpm --rcfile `dirname $0`/lib/rpmrc --define "_rpmlock_path /var/lock/rpm" "$@"
[ -e ~/.rpmmacros.orig ] && mv ~/.rpmmacros.orig ~/.rpmmacros
You can then use the temporary rpm installation by going to the temporary directory and running ./rpm.sh. It will still work on the system's package database.
Installing rpm's RPMs
This is easy now. First download rpm and required packages from a CentOS mirror. You need the packages for rpm, rpm-libs and sqlite (make sure you choose the right platform, i386 or x86_64). Then do a ./rpm.sh -i *.rpm so all these packages are installed at once. Now you can run the system's rpm again, phew!
Installing Yum
You may still need to get yum back. This is done similarly, by downloading the packages yum, yum-fastestmirror, yum-metadata-parser, rpm-python and python-sqlite. Then do a ./rpm.sh -i *.rpm for these and you've can install packages easily again.
