How to restore accidentally deleted /etc/bash.bashrc, without reinstalling Ubuntu? [duplicate]
Either restore that single file from bash's deb package:
$ apt-get download bash
$ dpkg-deb --fsys-tarfile bash_*.deb > /tmp/bash_pkg.tar
$ tar -Oxf /tmp/bash_pkg.tar ./etc/bash.bashrc | sudo tee /etc/bash.bashrc
Or restore all missing files of bash:
sudo apt-get -o Dpkg::Options::="--force-confmiss" install --reinstall bash
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There is also a file which might be helpful to you:
/usr/share/doc/adduser/examples/adduser.local.conf.examples/bash.bashrc
however I believe that this file is belong to adduser package.