Make text in xterm looks and feels like gnome-terminal

You can use a special wildcard syntax with :set <Key> to let Vim automatically recognize xterm-style modified keys:

if &term =~ '^gnome'
execute "set <xUp>=\e[1;*A"
execute "set <xDown>=\e[1;*B"
execute "set <xRight>=\e[1;*C"
execute "set <xLeft>=\e[1;*D"
execute "set <xHome>=\e[1;*H"
execute "set <xEnd>=\e[1;*F"
execute "set <PageUp>=\e[5;*~"
execute "set <PageDown>=\e[6;*~"
execute "set <F1>=\eOP"
execute "set <F2>=\eOQ"
execute "set <F3>=\eOR"
execute "set <F4>=\eOS"
execute "set <xF1>=\eO1;*P"
execute "set <xF2>=\eO1;*Q"
execute "set <xF3>=\eO1;*R"
execute "set <xF4>=\eO1;*S"
execute "set <F5>=\e[15;*~"
execute "set <F6>=\e[17;*~"
execute "set <F7>=\e[18;*~"
execute "set <F8>=\e[19;*~"
execute "set <F9>=\e[20;*~"
execute "set <F10>=\e[21;*~"
execute "set <F11>=\e[23;*~"
execute "set <F12>=\e[24;*~"
endif

See :help xterm-function-keys and :help xterm-modifier-keys.

As of 2017, the source-code (runner.py) did this:

        term = os.environ.get('TERMCMD', os.environ.get('TERM'))
        if term not in get_executables():
            term = 'x-terminal-emulator'
        if term not in get_executables():
            term = 'xterm'
        if isinstance(action, str):
            action = term + ' -e ' + action
        else:
            action = [term, '-e'] + action

so you should be able to put any xterm-compatible program name in TERMCMD. However, note the use of -e (gnome-terminal doesn't match xterm's behavior). If you are using Debian/Ubuntu/etc, the Debian packagers have attempted to provide a wrapper to hide this difference in the x-terminal-emulator feature. If that applies to you, you could set TERMCMD to x-terminal-emulator.

Followup - while the design of the TERMCMD feature has not changed appreciably since mid-2016, the location within the source has changed:

• Refactor and improve the TERMCMD handling moved it to ranger/ext/get_executables.py

That is implemented in get_term:

def get_term():
    """Get the user terminal executable name.
    Either $TERMCMD, $TERM, "x-terminal-emulator" or "xterm", in this order.
    """
    command = environ.get('TERMCMD', environ.get('TERM'))
    if shlex.split(command)[0] not in get_executables():
        command = 'x-terminal-emulator'
        if command not in get_executables():
            command = 'xterm'
    return command

which uses x-terminal-emulator as before.

There is a related use of TERMCMD in rifle.py, used for executing commands rather than (as asked in the question) for opening a terminal. Either way, the key to using ranger is x-terminal-emulator, since GNOME Terminal's developers do not document their command-line interface, while Debian developers have provided this workaround.

Quoting from Bug 701691 – -e accepts only one term; all other terminal emulators accept more than one term (which the developer refused to fix, marking it "not a bug"):

Christian Persch 2013-06-06 16:02:54 UTC

There are no docs for the gnome-terminal command line options.