To download a file using the curl command on the Linux or Unix command line, you can use the following syntax:
curl [options] [URL] -o [filename]
For example, to download the file at https://www.example.com/file.txt and save it as file.txt on your local system, you would run:
curl https://www.example.com/file.txt -o file.txt
In this example, https://www.example.com/file.txt is the URL of the file to be downloaded, and -o file.txt specifies the output filename.
Here are some additional options that you may find useful when downloading a file using curl:
-L: Follow redirects.-O: Save the file with the same name as on the remote server.-C -: Resume a partially-downloaded file.-#: Display a progress meter while downloading the file.-k: Allow insecure SSL connections.
For more information on using curl, you can consult the curl manual page by running man curl in a terminal window.