uname —
Print operating system name
The uname utility writes symbols representing one or
  more system characteristics to the standard output.
The following options are available:
  - -a
- Behave as though all of the options -mnrsvwere
      specified.
- -m
- print the machine hardware name.
- -n
- print the nodename (the nodename may be a name that the system is known by
      to a communications network).
- -p
- print the machine processor architecture name.
- -r
- print the operating system release.
- -s
- print the operating system name.
- -v
- print the operating system version.
If no options are specified, uname prints
    the operating system name as if the -s option had
    been specified.
The uname utility conforms to IEEE Std
  1003.2-1992 (“POSIX.2”). The -p
  option is an extension to the standard.