I came across this cool tip whilst browsing the blog of a fellow storage geek’s who’d posted on the Linux RAID list.
Basically you can insert a variety of characters inside braces to expand them. I guess like a smart shell expansion using the tab. The most obvious usage is a major timesaver for creating a backup of a file (which of course we all should do everytime we edit a config file!).
cp foobar.conf{,.bak}
will work as:
cp foobar.conf foobar.conf.bak
Many more examples are given here.