what does curl command do code example

Example 1: what is curl

curl is a command line client to send request and
get respond from command line, so it's basically 
it's just way to send a request and response. Where you
send it we call it client. But with postman we can do more
than just sending request end respond.
This tool is preferred for automation, 
since it is designed to work without user interaction.
curl can transfer multiple file at once.

Example 2: curl command

#usage:
curl <url>
#it returns the raw text of the page (or anything else) at <url> in the internet
#to stdout
#examples:
#put the output into <file>
curl <url> > <file>
#to search for <pattern>
curl <url> | grep /<pattern>/
#to uncompress the output
curl <url> | gunzip

#you get the hang of it.

#helpful if you are testing a server :)
#be sure to be on bash or powershell!

Example 3: curl command

curl --header "Authorization: key=AAAAbh_xxx-nI:APBAwd91bGn1OssamQlG4R1v84yXOv-6oynz1i4eNltzQLd5ojIiFSHvnCFHJyA33QcRfeAMa5As2mjfEjkRA_XA-YM8gsqEQssm3Ykrn8FSBEwwwkot5KPWY0zMefYB1RZj1ZlZfsWy" --header "Content-Type: application/json" -d '{"to": "f8UQCp0VHqCrBR0Yeiwx0:APA91bHuqLN7Wp40U2Wt8LS3VcRipttiViYF4TXHKP1Rusdov542XEgUYaVk9GIAEM3Q2kHcME5D85BsyWg7vk3H3oLhKJdNQLSNyoxzfnhGAvuQo4BiTZ43sIdVGQ7t86WQDn6s9HBj", "data": {"status": "New information!!!"}}' https://fcm.googleapis.com/fcm/send