While working on a file in a gui application, how to quickly open the parent directory of a file in the file browser?

Create the following script (give it proper permissions) and bind it to a keyboard shortcut (I have bound it to Super key + O). Now when you use the keyboard shortcut on focused gui applications that has some file open, the file will most probably open in Nemo.

#!/usr/bin/env bash

FOCUSED_WINDOW=$(xdotool getactivewindow)

PID_OF_FOCUSED_WINDOW=$(xdotool getwindowpid $Focused_Window)

# Function to return the first regular, readable, non-empty file
first_regular_file() {
    while IFS= read -r f; do
        # -f: is regular file
        # -r: readable
        # -s: non-empty
        # ! -L: not a symbolic link
        # Path does not include a hidden folder (no /.something/)
        if [ -f "$f" ] && [ -r "$f" ] && [ -s "$f" ] && [ ! -L "$f" ] && { [[ "$f" == /home/* ]] || [[ "$f" == /media/* ]]; } && [[ "$f" != *"/."* ]]; then
            echo "$f"
            return 0
        fi
    done
}

# Try finding a file from /proc/<pid>/fd
file=$(find "/proc/$PID_OF_FOCUSED_WINDOW/fd" -type l 2>/dev/null | first_regular_file)

# Fallback: try /proc/<pid>/cmdline
if [ -z "$file" ]; then
    file=$(tr '\0' '\n' < "/proc/$PID_OF_FOCUSED_WINDOW/cmdline" | first_regular_file)
fi

# Fallback: use lsof to find open files
if [ -z "$file" ]; then
    file=$(lsof -p "$PID_OF_FOCUSED_WINDOW" -Fn 2>/dev/null | cut -c2- | first_regular_file)
fi

# Open file in Nemo or show notification
if [ -n "$file" ]; then
    nemo "$file"
else
    notify-send "Could not detect a regular file for the focused window."
fi

NOTE: Install the dependencies of the scripts if they are not there. Specially you might have to install xdotool.

NOTE: I use nemo to open files but if you use other file explorer then you might have to change the script accordingly. Just replacing nemo with nautilus or something like that will most probably work.

NOTE: I have rewritten the answer. To check the original version please check edit history.

Tested Software:

• LibreOffice
• mpv
• Eye of GNOME
• Evince
• Foliate

NOTE: Please check your software and update this list (so that we know which apps are supported at this point).

Area of Improvement:

This solution does not work on some apps like vscode. However, they have their Right Click > Open Containing Folder options.

This also does not work on files which where opened using File > Open...

This would be functionality of the application, possibly provided via the GUI toolkit that the application uses, and not functionality of the operating system or the desktop environment. Since you're using Mint with Cinnamon, you're probably mostly using Gnome applications.

In most Gnome applications, with Gnome ≤3.36 (tested on Ubuntu 20.04), the following key sequence will work: Ctrl+O Alt+Up Shift+F10 Return

1. Ctrl+O is the usual Gnome keyboard shortcut for the “open” command. It opens to the Gtk file open dialog. Everything that follows works in any application that uses this file open dialog. The dialog opens on the directory containing the current file.
2. Alt+Up goes up to the current directory's parent directory. The previous directory, which is the directory you're interested in, is selected.
3. Shift+F10 brings up the context menu.
4. Return selects the first entry on the context menu, which is “Open With File Manager”.

With the mouse, that would be:

1. Select the “open file” command. (“Save as” would also work.)
2. The path to the current directory is displayed at the top, with each directory in a separate box. Click on the second box from the right, i.e. the parent of the current directory.
3. Right-click on the selected entry (which is the directory you're interested in) to bring up the context menu.
4. Choose “Open With File Manager” in the context menu.

I'm not a Gnome expert. Maybe there's a more convenient way.

With Gnome ≥3.38, this has unfortunately become a lot more cumbersome, because the file open dialog shows the “Recent” list by default. To see the directory containing the current file, you need to navigate to it in the left tab (with the keyboard: F6 Down Down…). Then you can use Alt+Up or the top bar to navigate to the parent directory.

With Kate (tested with 19.12.3), right-click on the file name in the tab header and choose “Open Containing Folder”.