Hiding Docker Exec output of a Postgres query - postgresql

Question

I'm using a Powershell script to start a Docker container with Postgres:
docker run -p ${host_port}:${remote_port} --name $container_name -d $database_name
# 0b. Wait for the container and the postgres database to be ready
Do
{
echo "Waiting for database system to start up..."
$timeout++
sleep 1
} until ((docker exec $container_name psql --username=$database_user_name --dbname=$database_name --command="SELECT 1;") -Or ($timeout -eq $timeout_limit))
if ($timeout -eq $timeout_limit)
{
Throw "Database system failed to start up."
exit
}
else {
# Do stuff
}
An issue I ran into was that the database was not always ready by the time I imported my schema. I added the Do-Until loop to continue "pinging" the database until it gets a response, or until 10 seconds have passed.
This works okay. And this is the console output:
Waiting for database system to start up...
psql: FATAL: the database system is starting up
Waiting for database system to start up...
Is there any way to prevent that second line from appearing?
psql: FATAL: the database system is starting up
I've tried to redirect the "pinging" to /dev/null but this fails when executing it like so,
docker exec $container_name psql --username=$database_user_name --dbname=$database_name --command="SELECT 1;" > /dev/null

Answer 1

I guess you have to redirect Stderr too. How does 2>&1 instead of just > work?