to quote the documentation:
> If an unquoted colon (:) followed by a psql variable name appears within
an argument, it is replaced by the variable's value, as described in SQL
Interpolation below.
> The forms :'variable_name' and :"variable_name" described there work as
well. The :{?variable_name}
Hi!
I want to check if I pass the parameter "param1" to a sql script
"delme.sql" like
```
\if ':param1'
\echo :param1;
\else
\prompt 'Param1? ' :param1
\endif
select :'param1';
```
if parameter `param1` is not passed, the .sql should ask for it.
If I run something like
`psql -f delme.sql -v pa
