Useful commands

adb kill-server
adb start-server
screencap -p file.png

Connect via adb to a device

/etc/udev/rules.d/99-adb.rules:

SUBSYSTEM=="usb", ATTR{idVendor}=="xxx", OWNER="user", GROUP="plugdev", MODE="666"

Don't forget to reload udev rules or restart udev.

Samsung Ace GT-S5839i

Boot modes

Recovery mode: power off the phone (if necessary remove the battery). Then hold power on + home button + volume up. When a boot screen appears, release first the home button then power, and finally volume up.
This mode is used to apply a patch from the SDcard or wipe partitions.
Download mode: power off the phone (if necessary remove the battery). Then hold power on + volume up AND volume down (yes, that's possible). A confirmation screen will appear. Confirm.
If that does not work, remove the battery. Hold power on and volume up and down while. Then put the battery back (still holding the buttons!).
This mode is used to restore a firmware using Odin.

Unbrick Samsung phone

What you need:

You need Odin, a tool that flashes the phone with ROMs. It should be possible to do it with Kies but I haven't managed to. Get Odin3 v1.84 with Pit file.
Get an official Samsung ROM. Beware, ROMs you get from samobile are not in the correct format and need to be repackaged using SplitFUS2, a tool I have been unable to find anylonger. However, this ROM is already re-packaged and can be used on a Samsung Ace GT-S5838i

What to do:

Get the necessary tools, and unpack
Put your phone in download mode.
Launch Odin and specify the PIT file, and from the ROM packaging: bootloader, CSC, phone (that is modem), PDA and CSC.
Plug in the phone. The phone should be seen on a COM port in yellow
Press start, sit back and relax. It takes a few minutes.
When Odin says it succeeded, you can unplug and reboot the phone.

Rooting the phone

You can root the phone using the universal root zip.

Put this zip on the SD card
Reboot in recovery mode
Apply patch from SD card and select the zip
Reboot

Unlock the phone

The phone may be locked to a given network. If that is the case, the simplest way to unlock is to call your operator. Otherwise, you may try to use the Galaxy Toolbox application. This requires the phone to be rooted.

Connecting an Android phone to your PC

$ adb devices

On Linux, if for some reason you get this:

./adb devices
List of devices attached 
????????????    no permissions

then, you may try this fix:

$ lsusb
...
Bus 002 Device 012: ID 04e8:685e Samsung Electronics Co., Ltd GT-I9100 Phone [Galaxy S II] (USB Debugging mode)

Then, in /etc/udev/rules.d, create a file named 99-adb.rules (as root):

SUBSYSTEM=="usb", ATTR{idVendor}=="04e8", OWNER="yourusername", GROUP="plugdev", MODE="666"

Then, reload the new rules:

$ sudo udevadm control --reload-rules
axelle@alligator /etc/udev/rules.d $ sudo service udev restart
udev stop/waiting
udev start/running, process 21321

Unplug and replug the phone, and it should work

$ adb devices
List of devices attached 
0123456789ABCDEF        device