Re: make pg_controldata accept "-D dirname"

Abhijit Menon-Sen wrote:

> P.S. Trivia: I can't find any other options in Postgres where the
> argument is mandatory but the option is optional.

psql behaves similarly with its -d and -U switches also; note --help:

Usage:
psql [OPTION]... [DBNAME [USERNAME]]
...
-d, --dbname=DBNAME database name to connect to (default: "alvherre")
...
-U, --username=USERNAME database user name (default: "alvherre")

Both are optional and have defaults. Datadir for pg_controldata is also
optional and --help contains this blurb:

If no data directory (DATADIR) is specified, the environment variable PGDATA
is used.

I think you could replace those lines with
-D data directory blah (default: "value of $PGDATA")

But psql --help doesn't use $PGUSER to expand the default value for -U;
I'm not clear if this means we shouldn't expand PGDATA in the help line
for pg_controldata, or need to fix psql to expand PGUSER in -U.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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