Timer in a loop - Bash - bash

Question

I have a token whos expire in 30 minutes, i want do renew this token until the 30 minutes time expire, i have the following script calling an api:
function token {
gen_bearer_token=$(curl -X POST "https://api.foo.bar/oauth2/token" -H "accept: application/json" -H "Content-Type: application/x-www-form-urlencoded" -d "client_id=foo&client_secret=bar" | cut -d '{' -f2 | cut -d '}' -f1)
bearer_token=$(echo $gen_bearer_token | awk '{print $2}' | cut -d '"' -f2 | cut -d '"' -f1)
token_type=$(echo $gen_bearer_token | awk '{print $6}' | cut -d '"' -f2 | cut -d '"' -f1)
}
echo -e "HOSTNAME;LAST_SEEN" > ${file}
ids=$(curl -s -X GET 'https://api.foo.bar/devices/queries/devices-scroll/v1?limit=5000' -H 'accept: application/json' -H 'authorization: '${token_type}' '${bearer_token}'' | jq .resources[])
for id in ${ids}
do
result=$(curl -s -X GET 'https://api.foo.bar/devices/entities/devices/v1?ids='${id}'' -H 'accept: application/json' -H 'authorization: '${token_type}' '${bearer_token}'' | jq '.resources[] | "\(.hostname) \(.last_seen)"')
if [[ ! -z ${result} ]]
then
hostname=$(echo ${result} | awk '{print $1}' | cut -d '"' -f2)
last_seen=$(echo ${result} | awk '{print $2}' | cut -d '"' -f1)
echo -e "${hostname};${last_seen}" >> ${file}
fi
done
in this looping, time duration is more than 2 hours (variable duration) + i want to create a timer to renew token if the times pass through 30 minutes, if passed 30 minutes the request in api will fail.
for id in ${ids}
do
result=$(curl -s -X GET 'https://api.foo.bar/devices/entities/devices/v1?ids='${id}'' -H 'accept: application/json' -H 'authorization: '${token_type}' '${bearer_token}'' | jq '.resources[] | "\(.hostname) \(.last_seen)"')
if [[ ! -z ${result} ]]
then
hostname=$(echo ${result} | awk '{print $1}' | cut -d '"' -f2)
last_seen=$(echo ${result} | awk '{print $2}' | cut -d '"' -f1)
echo -e "${hostname};${last_seen}" >> ${file}
fi
done

Answer 1

bash as a suitable timer built-in: the SECONDS variable.
Its value is its initial value plus the number of seconds since the most recent assignment. At shell start-up, it is initialized to 0.
All you need to do is check the value of $SECONDS before using the token, and if its value is greater than 1800 (the number of seconds in 30 minutes), get a new one.
SECONDS=1801 # Make sure a token will be generated before the first call
for id in $ids; do
if [ "$SECONDS" -gt 1800 ]; then
token
SECONDS=0
fi
...
done

Answer 2

I Solved this problem creating a check response with status code.
response=$(curl -H 'authorization: '${token_type}' '${bearer_token}'' --write-out '%{http_code}' --silent --output /dev/null https://api.foo.bar/devices/entities/devices/v1?ids='0000000000000')
if [ ${response} -eq 200 ]; then
do something
else
token
fi