globstar

Globstar is a feature of the Bash shell that enables recursive pathname expansion using the double asterisk pattern, **. When the Bash option globstar is enabled (for example, by running shopt -s globstar), patterns containing ** will recursively match files and directories across the entire path, not just the immediate directory.

With globstar enabled, ** matches zero or more directories. A common usage is to list or operate on files at any depth. For example, echo **/*.txt lists all files ending in .txt in the current directory and every subdirectory. Similarly, echo **/lib/*.so can locate shared library files in any subdirectory under the current location. The pattern **/* matches any file or directory at any depth, including the top level of the current directory.

Dotfiles and hidden paths require additional options. By default, Bash globbing does not match filenames that begin with a dot. To include hidden files and directories, enable dotglob (shopt -s dotglob) in combination with globstar, or explicitly pattern for dotfiles.

Compatibility and scope. Globstar is a Bash feature introduced in Bash 4.0. It is not part of the POSIX sh specification, and behavior may differ in other shells. Some shells, such as Zsh, provide recursive globbing with ** but with different rules and options.

Related considerations. Other globbing options that affect behavior include nullglob (allow pattern expansions to yield nothing when there are no matches) and failglob (treat unmatched patterns as errors). Understanding these options helps predict how recursive globs behave in scripts and interactive sessions.