OS X version from command line

xxx-macbookpro:~ name$ system_profiler

Response:-

system_profiler SPSoftwareDataType
Software:

    System Software Overview:

      System Version: macOS 10.14.6 (18G87)
      Kernel Version: Darwin 18.7.0
      Boot Volume: Macintosh HD
      Boot Mode: Normal
      Computer Name: xxx’s MacBook Pro (2)
      User Name: XX XX (XXXX)
      Secure Virtual Memory: Enabled
      System Integrity Protection: Enabled
      Time since boot: X days X:XX

xxx-macbookpro:~ name$ sw_vers
ProductName:    Mac OS X
ProductVersion:    10.14.6
BuildVersion:    18G87

xxx-macbookpro:~ name$ defaults read loginwindow SystemVersionStampAsString
10.14.6

Links

Apple docs