How Can I Set the Request Header for Curl?

Just use the -H parameter several times:

curl -H "Accept-Charset: utf-8" -H "Content-Type: application/x-www-form-urlencoded" 

To pass multiple headers in a curl request you simply add additional -H or --header to your curl command.

Example

//Simplified
$ curl -v -H 'header1:val' -H 'header2:val' URL

//Explanatory
$ curl -v -H 'Connection: keep-alive' -H 'Content-Type: application/json'  

Going Further

For standard HTTP header fields such as User-Agent, Cookie, Host, there is actually another way to setting them. The curl command offers designated options for setting these header fields:

• -A (or --user-agent): set "User-Agent" field.
• -b (or --cookie): set "Cookie" field.
• -e (or --referer): set "Referer" field.
• -H (or --header): set "Header" field

For example, the following two commands are equivalent. Both of them change "User-Agent" string in the HTTP header.

    $ curl -v -H "Content-Type: application/json" -H "User-Agent: UserAgentString" 
    $ curl -v -H "Content-Type: application/json" -A "UserAgentString" 

Sometimes changing the header is not enough, some sites check the referer as well:

curl -v \
     -H 'Host: restapi.some-site.com' \
     -H 'Connection: keep-alive' \
     -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' \
     -H 'Accept-Language: en-GB,en-US;q=0.8,en;q=0.6' \
     -e localhost \
     -A 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.65 Safari/537.36' \
     '

In this example the referer (-e or --referer in curl) is 'localhost'.