Can't unlock bootloader....what am I missing

I'm going nuts here. I use a mac, have had the 6p since preorder (well...since they shipped it) and I haven't had a need for unlocking or rooting (first phone ever to leave it stock) but I've got a few glitches and what not and wanted to flash the newest update released today rather than wait for OTA. Figured a complete wipe can't hurt. unfortunately the fastboot flashing unlock command isn't working. Developer options enabled, OEM unlock tab enabled...usb debugging enabled.....but when I enter ./fastboot flashing unlock this is what I get in terminal (yes mac requires the ./ before any command)
usage: fastboot [ <option> ] <command>

commands:
update <filename> reflash device from update.zip
flashall flash boot + recovery + system
flash <partition> [ <filename> ] write a file to a flash partition
erase <partition> erase a flash partition
format <partition> format a flash partition
getvar <variable> display a bootloader variable
boot <kernel> [ <ramdisk> ] download and boot kernel
flash:raw boot <kernel> [ <ramdisk> ] create bootimage and flash it
devices list all connected devices
continue continue with autoboot
reboot reboot device normally
reboot-bootloader reboot device into bootloader
help show this help message

options:
-w erase userdata and cache
-s <serial number> specify device serial number
-p <product> specify product name
-c <cmdline> override kernel commandline
-i <vendor id> specify a custom USB vendor id
-b <base_addr> specify a custom kernel base address
-n <page size> specify the nand page size. default: 2048

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