Check return status of psql command in unix shell scripting

psql return code is documented as:

EXIT STATUS
psql returns 0 to the shell if it finished normally, 1 if a fatal error
of its own occurs (e.g. out of memory, file not found), 2 if the
connection to the server went bad and the session was not interactive,
and 3 if an error occurred in a script and the variable ON_ERROR_STOP
was set.

You probably just want to use ON_ERROR_STOP.

Failure getting tested and reported to the shell:

$ psql -d test -v "ON_ERROR_STOP=1" <<EOF
select error;
select 'OK';
EOF

ERROR:  column "error" does not exist
LINE 1: select error;

$ echo $?
3

Failure getting ignored and not reported to the shell:

$ psql -d test  <<EOF
select error;
select 'OK';
EOF
ERROR:  column "error" does not exist
LINE 1: select error;
               ^
 ?column? 
----------
 OK
(1 row)

$ echo $?
0