To find out if a website is using gzip or deflate compression using the curl command on Linux or Unix, you can use the --write-out option to print information about the response to standard output.
For example, to check if https://www.example.com is using gzip or deflate compression, you can use the following command:
curl --write-out '%{content_encoding}' https://www.example.com
This will print the value of the content_encoding field in the response header to standard output. If the website is using gzip or deflate compression, the content_encoding field will contain the value gzip or deflate. If the website is not using compression, the content_encoding field will be empty.
For example:
$ curl --write-out '%{content_encoding}' https://www.example.com
gzip
In this example, the website is using gzip compression.
You can also use the -I option to print only the response header, and the -H option to include the Accept-Encoding field in the request header.
For example:
curl -I -H 'Accept-Encoding: gzip,deflate' https://www.example.com
This will print the response header, including the Content-Encoding field, which will indicate whether the website is using gzip or deflate compression.
For more information about how to use the curl command to find out if a website is using gzip or deflate compression, you can consult the curl documentation or seek assistance from a qualified Linux or Unix administrator.