curl is finally getting support for doing multiple independent requests specified in the same command line, which allows users to make even better use of curl's excellent persistent connection handling and more. I don't know when I first got the question of how to do a GET and a POST in a single command line with curl, but I do know that we've had the TODO item about adding such a feature mentioned since 2004 - and I know it wasn't added there right away...
Starting in curl 7.36.0, we can respond with a better answer: use the --next option!
curl has been able to work with multiple URLs on the command line virtually since day 1, but all the command line options would then mostly apply and be used for all specified URLs.
This new --next option introduces a "boundary", or a wall if you like, between options on the command line. The options set before --next will be handled as one request and the options set on the right side of --next will start adding up to another request. You of course then need to specify at least one URL per individual such section and you can add any number of --next on the command line. If the command line then gets too long, we also support the same logic and sequence in the "config files" which is the way you can specify command line arguments into a text file and have curl read them from there using -K or --config.
Here's a somewhat silly example to illustrate. This fist makes a POST and then a HEAD to two different pages on the same host:
curl -d FOO example.com/input.cgi --next --head example.com/robots.txt
Thanks to Steve Holme for his hard work on implementing this!