Files have permissions of the from rwx. Normally these for User, Group and Other. In addition, Linux supports ACLs.
SetFacl
setfacl is a tool to set acls; getfacl is its counterpart to get them. To e.g. give yourself (say your username is bob) write access to /usr/local/bin, you use the command
sudo setfacl -m u:bob:rwx /usr/local/binalternatively, you can do this for a group:
sudo setfacl -m g:adm:rwx /usr/local/bin