Postgresql – How to change the config_file location of a postgresql database for “service postgresql start”

I had a PostgreSQL 9.1 db that I just upgraded to 9.3 using

/usr/lib/postgresql/9.3/bin/pg_upgrade -b /usr/lib/postgresql/9.1/bin -B /usr/lib/postgresql/9.3/bin -d /var/lib/postgresql/9.1/main/ -D /var/lib/postgresql/9.3/main/ -O "-c config_file=/etc/postgresql/9.3/main/postgresql.conf" -o "-c config_file=/etc/postgresql/9.1/main/postgresql.conf"

following the instructions here, unfortunately realizing after that I hadn't looked to closely at the last bit.

After the upgrade (which was successful), I found that instead of the default location of the data directory (in this case /var/lib/postgresql/9.3/main), the option in the upgrade had now configured all of my PostgreSQL config files to be located at /etc/postgresql/9.1/main/.

I've spent a while looking for a way to change this and so far I've found that while hba_file and ident_file can be easily changed in postgresql.conf itself, the config_file cannot be set except through the postgres command line interface.

I tried using postgres with the -o "-c config_file=/var/lib/postgresql/9.3/main" option but it seems that this just tries to start another instance of the service, separate from what a service postgresql start does.

Running pg_ctl status -D ~/9.3/main/ I get

`/usr/lib/postgresql/9.3/bin/postgres "-D" "/var/lib/postgresql/9.3/main" "-c" "config_file=/etc/postgresql/9.3/main/postgresql.conf"`

which I take to mean that -c... /etc... is being passed to whatever starts the service. Based on my limited knowledge, I believe this to be /etc/init.d/postgresql with the start parameter. Looking into that, it seems to reference /usr/share/postgresql-common/init.d-functions which in turn contains the following towards the top

do_ctl_all() {
[ "$1" ] || { echo "Error: invalid command '$1'" >&2; exit 1; }
[ "$2" ] || { echo "Error: invalid version '$2'" >&2; exit 1; }
[ -d "/etc/postgresql/$2" ] || return 0
[ "$(ls /etc/postgresql/$2)" ] || return 0
[ -x "/usr/lib/postgresql/$2/bin/postmaster" ] || return 0
...

though I'm not sure if these have any relevance.

What I guess I'm asking is if there is any way to configure the config_file variable or customize how the service starts.

Thanks for any help! Sorry for my lack of understanding, I'm trying to learn more!