pgindent will indent .c and .h files according to the coding standards of
the PostgreSQL project. It needs several things to run, and tries to locate
or build them if possible. They can also be specified via command line switches
or the environment.

You can see all the options by running:

	pgindent --help

In its simplest form, if all the required objects are installed, simply run
it at the top of the source tree you want to process like this:

	pgindent .

If your pg_bsd_indent program is not installed in your path, you can specify
it by setting the environment variable INDENT, or PGINDENT, or by giving the
command line option --indent:

	pgindent --indent=/opt/extras/bsdindent

pgindent also needs a file containing a list of typedefs. This can be
specified using the PGTYPEDEFS environment variable, or via the command line
--typedefs option. If neither is used, it will look for it within the
current source tree, or in /usr/local/etc/typedefs.list.

We don't want to indent certain files in the PostgreSQL source. pgindent
will honor a file containing a list of patterns of files to avoid. This
file can be specified using the --excludes command line option. If indenting
a PostgreSQL source tree, this option is usually not necessary, as it will
find the file src/tools/pgindent/exclude_file_patterns. The --excludes option
can be used more than once to specify multiple files containing exclusion
patterns.

There are also two non-destructive modes of pgindent. If given the --show-diff
option pgindent will show the changes it would make, but doesn't actually make
them. If given instead the --silent-diff option, pgindent will exit with a
status of 2 if it finds any indent changes are required, but will not
make the changes or give any other information. This mode is intended for
possible use in a git pre-commit hook. An example of its use in a git hook
can be seen at https://wiki.postgresql.org/wiki/Working_with_Git#Using_git_hooks

Any non-option arguments are taken as the names of files to be indented. In this
case only these files will be changed, and nothing else will be touched.