Note: to get best performance it suggested to login before contest.
It is also wise to set contest ID before it started.
Examples (commands):
cf login exampleuser will try log in as exampleuser, asking for password if necessary;
cf login will try log in as previously logged user, asking for password if necessary;
cf submit x.c -prob=555a -lang=10 submits file x.c as solution for problem 555A, using compiler number 10;
cf submit x.c -prob=555a submits file x.c as solution for problem 555A, using default compiler for c;
cf submit a.c -prob=555 submits file a.c as solution for problem 555A, using default compiler for c;
cf con 555 from now all subsequent submit ops will use 555 as default contest;
cf submit x.c -prob=a submits file x.c as solution for problem 555A, using default compiler for c;
cf submit a.c submits file a.c as solution for problem 555A, using default compiler for c;
cf submit a will check if it is obvious which file do you want to submit and submit it using default (or specified) language as solution for problem A in default (or specified) contest.
Configuration will be in $HOME/config/.cf/conf file, cookies will be in separate files in the same directory as conf. Feel free to edit/delete/share this files at own risk.
Limitations:
= character in handle is not supported (probably also by the site).