These are the last two connection attempts of the linux log file:
12:26:31.614 post_compile: Begin
12:26:31.614 post_compile: Connect attempt to port 3149
12:26:31.614 post_compile: Connect attempt to port 3149
12:26:31.715 post_compile: Connect attempt to port 3149
12:26:31.715 post_compile: Connected to port 3149
12:26:31.720 post_compile: Sending command: comment: Teensyduino 1.40 - LINUX64 (teensy_post_compile)
12:26:31.720 post_compile: Sending status request
12:26:31.724 post_compile: Receive status dir = /tmp/arduino_build_626899/
12:26:31.762 post_compile: Receive status file = ACCELGYROMAGSD.ino.hex
12:26:31.762 post_compile: Receive status readable = 1
12:26:31.762 post_compile: Receive status auto = 0
12:26:31.762 post_compile: Receive status online = 0
12:26:31.762 post_compile: Receive status online_count = 0
12:26:31.762 post_compile: Receive status offline_count = 0
12:26:31.762 post_compile: Receive status state = 0
12:26:31.762 post_compile: Receive status EOT
12:26:31.762 post_compile: Sending command: auto
n
12:26:31.762 post_compile: Disconnect
12:26:31.783 post_compile: Begin
12:26:31.783 post_compile: Connect attempt to port 3149
12:26:31.783 post_compile: Connected to port 3149
12:26:31.783 post_compile: Sending command: comment: Teensyduino 1.40 - LINUX64 (teensy_post_compile)
12:26:31.784 post_compile: Sending status request
12:26:31.788 post_compile: Receive status dir = /tmp/arduino_build_626899/
12:26:31.826 post_compile: Receive status file = ACCELGYROMAGSD.ino.hex
12:26:31.826 post_compile: Receive status readable = 1
12:26:31.826 post_compile: Receive status auto = 1
12:26:31.826 post_compile: Receive status online = 0
12:26:31.826 post_compile: Receive status online_count = 0
12:26:31.826 post_compile: Receive status offline_count = 0
12:26:31.826 post_compile: Receive status state = 0
12:26:31.826 post_compile: Receive status EOT
12:26:31.826 post_compile: Disconnect
And this is from verbose when it managed to upload (after not responding, closing, opening again and uploading):
12:31:49.425: Teensy Loader 1.40, begin program
12:31:49.440: File "ACCELGYROMAGSD.ino.hex". 30628 bytes, 3% used
12:31:49.440: Listening for remote control on port 3149
12:31:49.440: initialized, showing main window
12:31:49.484: remote connection opened
12:31:49.486: remote cmd: "comment: Teensyduino 1.40 - LINUX64 (teensy_post_compile)"
12:31:49.487: remote cmd: "status"
12:31:49.496: Device came online, code_size = 1048576
12:31:49.496: Board is: Teensy 3.6 (MK66FX1M0), version 1.03
12:31:49.507: File "ACCELGYROMAGSD.ino.hex". 30628 bytes, 3% used
12:31:49.507: set background IMG_ONLINE
12:31:49.510: status data sent
12:31:49.556: remote connection closed
12:31:49.563: remote connection opened
12:31:49.563: remote cmd: "comment: Teensyduino 1.40 - LINUX64 (teensy_post_compile)"
12:31:49.564: remote cmd: "status"
12:31:49.564: status data sent
12:31:49.612: remote connection closed
12:31:49.615: remote connection opened
12:31:49.616: remote cmd: "show:arduino_attempt_reboot"
12:31:49.616: got request to show arduino rebooting message
12:31:49.618: remote cmd: "comment: Teensyduino 1.40 - LINUX64 (teensy_reboot)"
12:31:49.618: remote cmd: "status"
12:31:49.618: status data sent
12:31:49.658: remote cmd: "auto
n"
12:31:49.664: File "ACCELGYROMAGSD.ino.hex". 30628 bytes, 3% used
12:31:49.665: elf size appears to be 1048576
12:31:49.665: elf binary data matches hex file
12:31:49.665: Code size from .elf file = 1048576
12:31:49.665: begin operation
12:31:49.667: flash, block=0, bs=1024, auto=1
12:31:49.674: remote connection closed
12:31:49.674: flash, block=1, bs=1024, auto=1
12:31:49.678: flash, block=2, bs=1024, auto=1
12:31:49.680: flash, block=3, bs=1024, auto=1
12:31:49.956: flash, block=4, bs=1024, auto=1
12:31:49.958: flash, block=5, bs=1024, auto=1
12:31:49.975: flash, block=6, bs=1024, auto=1
12:31:49.977: flash, block=7, bs=1024, auto=1
12:31:49.994: flash, block=8, bs=1024, auto=1
12:31:49.996: flash, block=9, bs=1024, auto=1
12:31:50.013: flash, block=10, bs=1024, auto=1
12:31:50.015: flash, block=11, bs=1024, auto=1
12:31:50.017: flash, block=12, bs=1024, auto=1
12:31:50.034: flash, block=13, bs=1024, auto=1
12:31:50.036: flash, block=14, bs=1024, auto=1
12:31:50.053: flash, block=15, bs=1024, auto=1
12:31:50.055: flash, block=16, bs=1024, auto=1
12:31:50.072: flash, block=17, bs=1024, auto=1
12:31:50.073: flash, block=18, bs=1024, auto=1
12:31:50.091: flash, block=19, bs=1024, auto=1
12:31:50.093: flash, block=20, bs=1024, auto=1
12:31:50.095: flash, block=21, bs=1024, auto=1
12:31:50.112: flash, block=22, bs=1024, auto=1
12:31:50.113: flash, block=23, bs=1024, auto=1
12:31:50.131: flash, block=24, bs=1024, auto=1
12:31:50.132: flash, block=25, bs=1024, auto=1
12:31:50.149: flash, block=26, bs=1024, auto=1
12:31:50.151: flash, block=27, bs=1024, auto=1
12:31:50.168: flash, block=28, bs=1024, auto=1
12:31:50.170: flash, block=29, bs=1024, auto=1
12:31:50.173: sending reboot
12:31:50.190: begin wait_until_offline
12:31:50.290: HID/linux: something changed, try reading a descriptor
12:31:50.291: HID/linux: Device was just disconnected
12:31:50.291: offline, waited 2
12:31:50.291: end operation, total time = 0.626 seconds
12:31:50.291: set background IMG_REBOOT_OK
12:31:50.294: redraw timer set, image 14 to show for 1200 ms
12:31:51.494: redraw, image 9
12:31:56.942: Verbose Info event