# Common Command Line Options

The Perseid utilities support the following command line options:

`-h`, `--help`
:   Show help about the program's command line arguments, and exit.

`-H <host>`, `--host <host>`
:   Specifies the **host name** of the machine on which the PostgreSQL
    server is running.  The default host name is determined by
    PostgreSQL (normally, a Unix-domain socket or `localhost`).

`-p <port>`, `--port <port>`
:   Specifies the **port** on which the PostgreSQL server is listening
    for connections.  The default port number is determined by
    PostgreSQL (normally, 5432).

`-U <username>`, `--username <username>`
:   PostgreSQL **user name** to connect as.  The default user name is
    determined by PostgreSQL (normally, the name of the operating
    system user running the program).

`-W`, `--password`
:   Force the program to prompt for a password before connecting to a
    database.  If this option is not specified and password
    authentication is required, the program will resort to `libpq`
    defaults, i.e., the [password
    file](https://www.postgresql.org/docs/current/libpq-pgpass.html)
    or the [PGPASSWORD environment
    variable](https://www.postgresql.org/docs/current/libpq-envars.html).

`--version`
:   Show the program's version number and exit.

Short options (those only one character long) can be concatenated with
their value arguments, e.g.,

```
dbtoyaml -p5433 dbname
```

Several short options can be joined together, using only a single `-`
prefix, as long as only the last option (or none of them) requires a
value:

```
yamltodb -Bu dbname spec
```

Long options can be separated from their arguments by a `=` or passed
as two separate arguments, e.g.:

```
dbtoyaml --port=5433 dbname
```

or:

```
dbtoyaml --port 5433 dbname
```