| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/golang/glog | Package glog implements logging analogous to the Google-internal C++ INFO/ERROR/V setup. |
| io | Package io provides basic interfaces to I/O primitives. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| os/exec | Package exec runs external commands. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| time | Package time provides functionality for measuring and displaying time. |