set statement_timeout does not work

Hi,

I try to set the statement_timeout so that "select pg_stop_backup();"
will not hang if archive command failed. Below are the command and
errors.

psql.exe" -d mydb -h myhost -p 5432 -U postgres -w -c "set
statement_timeout = 1000; select pg_stop_backup();"
WARNING: pg_stop_backup still waiting for archive to complete (60
seconds elapsed)
WARNING: pg_stop_backup still waiting for archive to complete (120
seconds elapsed)
WARNING: pg_stop_backup still waiting for archive to complete (240
seconds elapsed)
WARNING: pg_stop_backup still waiting for archive to complete (480
seconds elapsed)

I also tried to run the two commands seperately as below. It also does not work.

psql.exe" -d mydb -h myhost -p 5432 -U postgres -w -c "set
statement_timeout = 1000;"
psql.exe" -d mydb -h myhost -p 5432 -U postgres -w -c "select pg_stop_backup();"

If I change the "statement_timeout" setting of postgresql.conf, it
works. But it will afftect all the queries.

How to use psql to do it?

Thanks.

Jack