curl https://login.salesforce.com/services/oauth2/token -d "grant_type=password" -d
"client_id=myclientid" -d "client_secret=myclientsecret" -d "mylogin@salesforce.com" -d
"password=mypassword123456"

{"error":"invalid_grant","error_description":"authentication failure"}

curl https://login.salesforce.com/services/oauth2/token -d "grant_type=password" -d
"client_id=XXXXXX.YYYYY_ZZZZZ" -d "client_secret=000099990000" -d "name@domain.com" -d
"password=yourpasswordyoursecuritytoken"

curl https://login.salesforce.com/services/oauth2/token -d "grant_type=password" -d
"client_id=XXXXXX.YYYYY_ZZZZZ" -d "client_secret=000099990000" -d "username=name@domain.com" -d
"password=yourpasswordyoursecuritytoken"

{
  "error" : "invalid_grant",
  "error_description" : "authentication failure"
}