Até mesmo a página do manual do Bash 2.0 contém uma seção sobre Expansão do Brace . A partir dos arquivos do FreeBSD, o manpage de bash (1)
para o CentOS 3.9 :
Brace Expansion
Brace expansion is a mechanism by which arbitrary strings may be gener-
ated. This mechanism is similar to pathname expansion, but the file-
names generated need not exist. Patterns to be brace expanded take the
form of an optional preamble, followed by a series of comma-separated
strings between a pair of braces, followed by an optional postscript.
The preamble is prefixed to each string contained within the braces,
and the postscript is then appended to each resulting string, expanding
left to right.
...
GNU Bash-2.05b 2002 July 15 BASH(1)
Suponho que você só precisa pesquisar mais.