Making the Backspace key go to the previous folder in Finder

Solution 1:

While the solution offered by barbaz is a decent one, there actually is a perfect one :), which removes the limitation that doesn't allow you to use Backspace in text fields in Finder (e.g. when renaming files, or typing in the search field).

1. Install an awesome Karabiner app that allows you to remap almost anything you don't like to anything you like
2. Find and edit private.xml file per instructions in the link (and read how to update Karabiner to include private.xml in the main list when you get to step 4)

3. Insert the following code and save private.xml file:

   <item> <name>Backspace in Finder moves Up</name>⌥ <appendix> (except when editing text fields)</appendix> <identifier>private.Backspace_MoveUp</identifier> <only>FINDER</only> <uielementrole_not>AXTextArea, AXTextField</uielementrole_not> <autogen>__KeyToKey__ KeyCode::DELETE, ModifierFlag::NONE, KeyCode::CURSOR_UP, VK_COMMAND</autogen> </item>

   This does the following:

   • Assigns ⌥ Opt + ↑ to Backspace key.
     • Note: in my OS X Yosemite it is the shortcut for 'Go Up' command in Finder (e.g. it always goes to the folder one level above the one you're in). If you don't like the 'Go Up' command and would like to go to the previous folder - define your own shortcut as per babraz' answer, then paste the respective key combination instead of CURSOR_UP, VK_COMMAND code above
   • Limits this command to Finder only
   • Limits this command to non-text fields only
4. Open Karabiner and click on "ReloadXML" button (see link in 2. for details on how to add custom private.xml)
5. Select "Backspace in Finder moves up" command
6. Enjoy :)

Solution 2:

You can press CMD-[ (as shown in the "Go" menu). Using the regular way from there (Keyboard Preferences -> Keyboard Shortcuts and assign a new shortcut for the "Back" entry) doesn't work since the "Keyboard Shortcut" field does not accept the backspace character. But you can:

• Go to System Preferences, Keyboard, Keyboard shortcuts
• Create a new keyboard shortcut for Finder with the Menu Title "Back"
• Use any arbitrary keyboard shortcut

Then edit the file $HOME/Library/Preferences/com.apple.finder.plist and change the keyboard shortcut to "⌫" for example using XCode:

Now, if you restart Finder (using killall Finder or the Force Quit Applications dialog) you will be able to use the shortcut:

However, as pointed out in the comments, the backspace key is probably not usable in the keyboard dialog for a reason, since using it as a shortcut will trigger the action when you have the cursor in an edit box, where you'd want backspace to remove characters.

Solution 3:

Althouhg the most voted answer, with the "uielementrole_not", was perfect back in the day, it doesn't work in the lastest versions of Karabiner, as uielementrole_not is not an option available.

Being unable to add that specific condition had very bad side effects like the one the original poster says and others.

Well, I have found a way to avoid that in newer versions, using Karabiner variables. The idea is detecting when you are in edit mode. It's far from being perfect (see notes at the bottom) but it's far better than nothing.

This is the list of keystrokes and how they should work:

• F2 ----> Rename file
• Enter -> Open file
• Backspace --> Upper folder

This is what I do:

• When someone presses F2 on Finder I replace with enter (default key for "rename") and set "onedit" variable to 1
• When someone presses Enter or Esc on Finder, if onedit=1 then I keep same key code and set onedit to 0.
• When someone presses enter and onedit=0, then I send the keystrokes for "open"
• When someone presses backspace and onedit=0, then I send the keystrokes for "folder up"
• When someone presses backspace and onedit=1, then I keep the backspace key

These are all the rules to perform that:

{
    "description": "Use F2 as Rename and enter edit mode",
    "manipulators": [
        {
            "conditions": [
                {
                    "bundle_identifiers": [
                        "^com.apple.finder"
                    ],
                    "type": "frontmost_application_if"
                }
            ],
            "from": {
                "key_code": "f2"
            },
            "to": [
                    {"key_code": "return_or_enter"},
                    {"set_variable": 
                        {
                        "name": "onedit",
                        "value": 1
                        }
                    }
            ],
            "type": "basic"
        }
    ]
}
,
{
    "description": "Use Backspace as Go to Previous Folder in Finder if not editing",
    "manipulators": [
        {
            "conditions": [
                {
                    "bundle_identifiers": [
                        "^com.apple.finder"
                    ],
                    "type": "frontmost_application_if"
                }
                ,
                {
                    "type": "variable_unless",
                    "name": "onedit",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "delete_or_backspace"
            },
            "to": [
                {
                    "key_code": "open_bracket",
                    "modifiers": [
                        "left_command",
                        "left_option"
                    ]
                }
            ],
            "type": "basic"
        }
    ]
},
{
    "description": "Use Return as Open if not renaming file",
    "manipulators": [
        {
            "conditions": [
                {
                    "bundle_identifiers": [
                        "^com.apple.finder"
                    ],
                    "type": "frontmost_application_if"
                }
                ,
                {
                    "type": "variable_unless",
                    "name": "onedit",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "return_or_enter",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "o",
                    "modifiers": [
                        "right_command"
                    ]
                }
            ],
            "type": "basic"
        }
    ]
},
{
    "description": "Use Return to finish renaming when onedit=1",
    "manipulators": [
        {
            "conditions": [
                {
                    "bundle_identifiers": [
                        "^com.apple.finder"
                    ],
                    "type": "frontmost_application_if"
                },
                {
                    "name": "onedit",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "return_or_enter",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {"key_code": "return_or_enter"},
                {"set_variable": 
                    {
                    "name": "onedit",
                    "value": 0
                    }
                }
            ],
            "type": "basic"
        }
    ]
},
{
    "description": "Use Esc to finish renaming when onedit=1",
    "manipulators": [
        {
            "conditions": [
                {
                    "bundle_identifiers": [
                        "^com.apple.finder"
                    ],
                    "type": "frontmost_application_if"
                },
                {
                    "name": "onedit",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "escape",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {"key_code": "escape"},
                {"set_variable": 
                    {
                    "name": "onedit",
                    "value": 0
                    }
                }
            ],
            "type": "basic"
        }
    ]
}

Notes:

• Any press of F2 on Finder will make Karabiner enter in rename mode, so if you press F2 on anything that is not a file, backspace and other Windows-like shortcuts will stop working until you press Esc or Enter.
• Make sure you don't have any other rules for F2, Enter, Backspace, as they may trigger before this rules and mess it all up.