I am unable to find a suitable utility to just indicate the file system usage (% space free for partitions) on the panel.

And I am not looking forward to install any bad kinds of desktop management tool, but a simple indicator.

I appreciate all your suggestions.


EDIT:

1. NEW ANSWER

While the answer at the bottom of this one can be used (see [2.]), it lead to a ppa -version with additional options, to be set in a preferences window.

enter image description here

enter image description here

Options include:

  • Setting all aliases in one window
  • Setting theme colors for the panel icon:

    enter image description hereenter image description hereenter image description hereenter image description here

  • Setting threshold for warnings
  • Show info on newly mounted / connected volumes in a notification:

    enter image description here

  • Run on Startup

Furthermore, the indicator now includes a smaller (width) icon set for other distro's (like xfce), which will be automatically applied, depending on the window manager.

enter image description here

To install:

sudo add-apt-repository ppa:vlijm/spaceview
sudo apt-get update
sudo apt-get install spaceview



2. OLD ANSWER

The script below is an indicator that lists your devices and shows their usage. The information is updated (if necessary) once per ten seconds.

enter image description here

Furthermore

  • While the indicator is running, you can choose a device to be represented in the icon. The device will be remembered on the next time you run the indicator:

    enter image description here

    ![enter image description here

    enter image description here

  • For one or more (or all) devices, you can set an alternative name ("custom name"), to be set in the head of the script

    As an example, this:

    alias = [
        ["sdc1", "stick"],
        ["sdb1", "External"],
        ["sda2", "root"],
        ["sda4", "ntfs1"],
        ["sda5", "ntfs2"],
        ["//192.168.0.104/media", "netwerk media"],
        ["//192.168.0.104/werkmap_documenten", "netwerk docs"],
        ]
    

    Will show:

    enter image description here

  • You can set a threshhold; if the free space of either one of your devices is below that, you'll get a warning:

    enter image description here

  • Plugged/unplugged devices will be added/removed from the menulist within 10 seconds.

The script

#!/usr/bin/env python3
import subprocess
import os
import time
import signal
import gi
gi.require_version('Gtk', '3.0')
gi.require_version('AppIndicator3', '0.1')
from gi.repository import Gtk, AppIndicator3, GObject
from threading import Thread

#--- set alias names below in the format [[device1, alias1], [device2, alias2]]
#--- just set alias = [] to have no custom naming
alias = []
#--- set the threshold to show a warning below 
#--- set to 0 to have no warning
threshold = 17
#---
currpath = os.path.dirname(os.path.realpath(__file__))
prefsfile = os.path.join(currpath, "showpreferred")

class ShowDevs():
    def __init__(self):
        self.default_dev = self.get_showfromfile()
        self.app = 'show_dev'
        iconpath = currpath+"/0.png"
        self.indicator = AppIndicator3.Indicator.new(
            self.app, iconpath,
            AppIndicator3.IndicatorCategory.OTHER)
        self.indicator.set_status(AppIndicator3.IndicatorStatus.ACTIVE)       
        self.indicator.set_menu(self.create_menu())
        self.indicator.set_label("Starting up...", self.app)
        self.update = Thread(target=self.check_changes)
        self.update.setDaemon(True)
        self.update.start()

    def check_changes(self):
        state1 = None
        while True:
            self.state2 = self.read_devices()
            if self.state2 != state1:
                self.update_interface(self.state2)
            state1 = self.state2
            time.sleep(10)

    def update_interface(self, state):
        warning = False; self.newmenu = []
        for dev in state:
            mention = self.create_mention(dev)
            name = mention[0]; deci = mention[2]; n = mention[1]
            if n <= threshold:
                warning = True
            try:
                if self.default_dev in name:
                    newlabel = mention[3]
                    newicon = currpath+"/"+str(10-deci)+".png"
            except TypeError:
                pass
            self.newmenu.append(name+" "+str(n)+"% free")
        if warning:
            newlabel = "Check your disks!"
            newicon = currpath+"/10.png"
        try:
            self.update_indicator(newlabel, newicon)
        except UnboundLocalError:
            labeldata = self.create_mention(state[0])
            newlabel = labeldata[3]
            newicon = currpath+"/"+str(10-labeldata[2])+".png"
            self.update_indicator(newlabel, newicon)
        GObject.idle_add(self.set_new, 
            priority=GObject.PRIORITY_DEFAULT)  

    def update_indicator(self, newlabel, newicon):
        GObject.idle_add(self.indicator.set_label,
            newlabel, self.app,
            priority=GObject.PRIORITY_DEFAULT)   
        GObject.idle_add(self.indicator.set_icon,
            newicon,
            priority=GObject.PRIORITY_DEFAULT)

    def set_new(self):
        for i in self.initmenu.get_children():
            self.initmenu.remove(i)
        for item in self.newmenu:
            add = Gtk.MenuItem(item)
            add.connect('activate', self.change_show)
            self.initmenu.append(add) 
        menu_sep = Gtk.SeparatorMenuItem()
        self.initmenu.append(menu_sep)
        self.item_quit = Gtk.MenuItem('Quit')
        self.item_quit.connect('activate', self.stop)
        self.initmenu.append(self.item_quit)
        self.initmenu.show_all()

    def change_show(self, *args):
        index = self.initmenu.get_children().index(self.initmenu.get_active())
        self.default_dev = self.newmenu[index].split()[0]
        open(prefsfile, "wt").write(self.default_dev)
        self.update_interface(self.read_devices())

    def create_mention(self, dev):
        name = dev[1] if dev[1] else dev[0]
        n = dev[2]; deci = round(dev[2]/10)
        newlabel = name+" "+str(n)+"% free"
        return (name, n, deci, newlabel)        

    def create_menu(self):
        # create initial basic menu
        self.initmenu = Gtk.Menu()
        self.item_quit = Gtk.MenuItem('Quit')
        self.item_quit.connect('activate', self.stop)
        self.initmenu.append(self.item_quit)
        self.initmenu.show_all()
        return self.initmenu

    def read_devices(self):
        # read the devices, look up their alias and the free sapace
        devdata = []
        data = subprocess.check_output(["df", "-h"]).decode("utf-8").splitlines()
        relevant = [l for l in data if all([
                    any([l.startswith("/dev/"), l.startswith("//")]),
                    not "/loop" in l])
                    ]
        for dev in relevant:
            data = dev.split(); name = data[0]; pseudo = None       
            free = 100-int([s.strip("%") for s in data if "%" in s][0])
            for al in alias:
                if al[0] in name:
                    pseudo = al[1]
                    break
            devdata.append((name, pseudo, free)) 
        return devdata

    def get_showfromfile(self):
        # read the preferred default device from file
        try:
            defdev = open(prefsfile).read().strip()
        except FileNotFoundError:
            defdev = None
        return defdev

    def stop(self, source):
        Gtk.main_quit()

ShowDevs()
GObject.threads_init()
signal.signal(signal.SIGINT, signal.SIG_DFL)
Gtk.main()

The icons

enter image description here 0.png

enter image description here 1.png

enter image description here 2.png

enter image description here 3.png

enter image description here 4.png

enter image description here 5.png

enter image description here 6.png

enter image description here 7.png

enter image description here 8.png

enter image description here 9.png

enter image description here 10.png

Setting up

Setting up is simple:

  • Copy the script into an empty file, save it as showusage.py
  • Save the icons above, exactly named as in their label, into one and the very same directory as the script (right- click > Save as)
  • In the headsection of the script, set (possible) alternative names (aliasses). Below an example:

    alias = [
        ["sda2", "root"],
        ["sdb1", "External"]
        ]
    

    If you want to display the devices unchanged, use:

    alias = []
    

    ...and if you want, change the threshold to show a warning:

    #--- set the threshold to show a warning below (% free, in steps of 10%)
    #--- set to 0 to have no warning
    threshold = 10
    

    That's it

Running it

To use the indicator, run the command:

python3 /path/to/showusage.py

To add it to Startup Applications, use the command:

/bin/bash -c "sleep 10 && python3 /path/to/showusage.py"

Choose Applications: Dash > Startup Applications > Add, add the command above.


disclaimer: I am author of this indicator and it is written for this specific question

Update Oct 23,2018

The indicator now supports listing network shares. Thanks to mihaigalos

Update Oct 29, 2016

The indicator now has unmount functionality and aliases have been made unique by referring to UUID of each partition instead of block device name such as sda1. See the related bug report

Update , Oct 8,2016

The indicator is now in version 2.0, has added a few features and has its own PPA.

To install from PPA, use the following steps in terminal:

  1. sudo apt-add-repository ppa:udisks-indicator-team/ppa
  2. sudo bash -c 'apt-get update && apt-get install udisks-indicator'

As mentioned in the release notes the features include:

  • Icons for menu entries: each partition/device has appropriate icon attached to it. If the device is usb disk , removable media icon is used, if it's iso image - the optical disk icon is used, and obviously hard drive/SSD partitions have drive icons.
  • Usage is now shown in percentage and human-readable values ( powers of 1024 ).
  • Graphical representation of usage via usage bar ( big thanks to Mateo Salta for the idea )
  • Preferences dialog : users can turn off certain fields that they do not want to see per each menu entry. This allows keeping indicator menu clean if there is a large amount of partitions attached. ( Thanks to Zacharee's request)
  • Text spacing: with default Ubuntu font and Monospace fonts, the text entries are nicely spaced to have cleaner look and enhance readability of the information.
  • Notification bubbles in case partition cannot be mounted

Below is the screenshot with default Ubuntu icon theme: enter image description here

Ubuntu Kylin icon theme

enter image description here

With all optional fields off

enter image description here

Design choices and additional thoughts:

In the making of this indicator , I hoped to achieve a utility that would be suitable for advanced and casual users alike. I tried to address some of the issues that I've noticed the new users may have with handling command line tools. In addition, the utility strives to be multipurpose.

The Preferences dialog allows making the indicator as complex and/or as simple as the user desires. It was also a specific design decision to avoid having label in the top panel so that it doesn't take up too much of user's top panel space. In addition, this indicator strives to be multipurpose utility that allows mounting partitions as well as opening their respective directories. This can be used not just as disk usage utility , but also as navigation utility for quick opening of the directories.

It is also convenient for users to know which partition inhabits which disk, thus avoiding frequent confusion with mounting via command line utilities such as mount. Instead it employs udisksctl for that purpose ( as well as obtaining the information from UDisks2 daemon, hence the naming ). The only task that it does not perform is unmounting , and or this reason the Open Disks Utility menu entry is included.

While originally I strived to make it similar to iStat menulet , the project diverged from this goal - the indicator is unique in it's design and purpose. I hope it will be found useful for many users and make their Ubuntu experience much more pleasant.


udisks-indicator (original answer)

Indicator for Ubuntu with Unity desktop to show disk usage Sample Screenshot

Overview

This indicator for Ubuntu with Unity allows easily view information about your mounted partitions. It strives to be visually similar to iStat Menu 3 menulet from OS X.

Entries are organized in order:

  • Partition
  • Alias ( if set by user )
  • Disk Drive to which partition belongs
  • Mountpoint of the partition ( directory )
  • % Usage

Clicking on each partition entry will open the partition's mountpoint in the default file manager

The "Unmounted Partitions" menu lists all the partitions not currently mounted by the system. Clicking on any entry in that submenu will mount that partition automatically, typically to /media/username/drive-id folder

The indicator uses default icons provided with the system, so the icon should be changing as you change the icon theme using Unity Tweak Tool or other methods

NOTE: if you want to add multiple aliases at the same time, instead of one by one via "Make Alias" option, you can do so via editing the ~/.partition_aliases.json configuration file. The format is as follows:

{
    "sda1": "Alias 1",
    "sda2": "Alias 2",
    "sdb1": "Alias 3"
}

Installation

PPA for easy installation is coming soon . . .

In the mean time, here are alternative steps:

  1. cd /tmp
  2. wget https://github.com/SergKolo/udisks-indicator/archive/master.zip
  3. unzip master.zip
  4. sudo install udisks-indicator-master/udisks-indicator /usr/bin/udisks-indicator
  5. sudo install udisks-indicator-master/udisks-indicator.desktop /usr/share/applications/udisks-indicator.desktop

All these steps can be put into a nice little installation script:

#!/bin/bash

cd /tmp
rm master.zip*
wget https://github.com/SergKolo/udisks-indicator/archive/master.zip
unzip master.zip
install udisks-indicator-master/udisks-indicator /usr/bin/udisks-indicator
install udisks-indicator-master/udisks-indicator.desktop /usr/share/applications/udisks-indicator.desktop

Source code

Original source code (Version v1.0) with basic functionality of this indicator can be found below. For newest features , check GitHub repository for this project. Please report any feature requests as well as errors on GitHub.

The /usr/bin/udisks-indicator:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

#
# Author: Serg Kolo , contact: [email protected]
# Date: September 27 , 2016
# Purpose: appindicator for displaying mounted filesystem usage
# Tested on: Ubuntu 16.04 LTS
#
#
# Licensed under The MIT License (MIT).
# See included LICENSE file or the notice below.
#
# Copyright © 2016 Sergiy Kolodyazhnyy
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
import gi
gi.require_version('AppIndicator3', '0.1')
from gi.repository import GLib as glib
from gi.repository import AppIndicator3 as appindicator
from gi.repository import Gtk as gtk
from os import statvfs
#from collections import OrderedDict
import subprocess
import shutil
import dbus
import json
import os

class UdisksIndicator(object):

    def __init__(self):
        self.app = appindicator.Indicator.new(
            'udisks-indicator', "drive-harddisk-symbolic.svg",
            appindicator.IndicatorCategory.HARDWARE
            )

        if not self.app.get_icon():
           self.app.set_icon("drive-harddisk-symbolic")

        self.app.set_status(appindicator.IndicatorStatus.ACTIVE)

        filename = '.partition_aliases.json'
        user_home = os.path.expanduser('~')
        self.config_file = os.path.join(user_home,filename)
        self.cache = self.get_partitions()
        self.make_menu()
        self.update()


    def update(self):
        timeout = 5
        glib.timeout_add_seconds(timeout,self.callback)

    def callback(self):
        if self.cache != self.get_partitions():
            self.make_menu()
        self.update()        

    def make_menu(self,*args):
        """ generates entries in the indicator"""
        if hasattr(self, 'app_menu'):
            for item in self.app_menu.get_children():
                self.app_menu.remove(item)

        self.app_menu = gtk.Menu()

        partitions = self.get_partitions()
        for i in partitions:

            part = "Partition: " + i[0]
            alias = self.find_alias(i[0])
            drive = "\nDrive: " + i[1]
            mount = "\nMountPoint: " + i[2]
            usage = "\n%Usage: " + i[3]

            item = part + drive + mount + usage
            if alias:
                alias = "\nAlias: " + alias
                item = part + alias + drive + mount + usage

            self.menu_item = gtk.MenuItem(item)
            self.menu_item.connect('activate',self.open_mountpoint,i[2])
            self.app_menu.append(self.menu_item)
            self.menu_item.show()

            self.separator = gtk.SeparatorMenuItem()
            self.app_menu.append(self.separator)
            self.separator.show()

        self.unmounted = gtk.MenuItem('Unmounted Partitions')
        self.unmounted_submenu = gtk.Menu()
        self.unmounted.set_submenu(self.unmounted_submenu)

        for i in self.get_unmounted_partitions():

            # TODO: add type checking, prevent swap

            part = "Partition: " + i[0]
            alias = self.find_alias(i[0])
            drive = "\nDrive: " + i[1]
            label = part + drive
            if alias: 
               alias = "\nAlias: " + alias
               label = part + alias + drive

            self.menu_item = gtk.MenuItem(label)
            self.menu_item.connect('activate',self.mount_partition,i[0])
            self.unmounted_submenu.append(self.menu_item)
            self.menu_item.show()

            self.separator = gtk.SeparatorMenuItem()
            self.unmounted_submenu.append(self.separator)
            self.separator.show()

        self.app_menu.append(self.unmounted)
        self.unmounted.show()


        self.separator = gtk.SeparatorMenuItem()
        self.app_menu.append(self.separator)
        self.separator.show()

        self.make_part_alias = gtk.MenuItem('Make Alias')
        self.make_part_alias.connect('activate',self.make_alias)
        self.app_menu.append(self.make_part_alias)
        self.make_part_alias.show()

        user_home = os.path.expanduser('~')
        desktop_file = '.config/autostart/udisks-indicator.desktop'
        full_path = os.path.join(user_home,desktop_file)

        label = 'Start Automatically' 
        if os.path.exists(full_path):
           label = label + ' \u2714'
        self.autostart = gtk.MenuItem(label)
        self.autostart.connect('activate',self.toggle_auto_startup)
        self.app_menu.append(self.autostart)
        self.autostart.show()

        self.open_gnome_disks = gtk.MenuItem('Open Disks Utility')
        self.open_gnome_disks.connect('activate',self.open_disks_utility)
        self.app_menu.append(self.open_gnome_disks)
        self.open_gnome_disks.show()

        self.quit_app = gtk.MenuItem('Quit')
        self.quit_app.connect('activate', self.quit)
        self.app_menu.append(self.quit_app)
        self.quit_app.show()

        self.app.set_menu(self.app_menu)

    def mount_partition(self,*args):
        # TODO: implement error checking for mounting
        return self.run_cmd(['udisksctl','mount','-b','/dev/' + args[-1]])

    def get_mountpoint_usage(self,mountpoint):
        fs = statvfs(mountpoint)
        usage = 100*(float(fs.f_blocks)-float(fs.f_bfree))/float(fs.f_blocks)
        return str("{0:.2f}".format(usage))

    def get_partitions(self):
        objects = self.get_dbus('system', 
                           'org.freedesktop.UDisks2', 
                           '/org/freedesktop/UDisks2', 
                           'org.freedesktop.DBus.ObjectManager',
                           'GetManagedObjects',
                           None)


        partitions = []
        for item in objects:
            try:
                if 'block_devices'  in str(item):


                       drive = self.get_dbus_property('system',
                                        'org.freedesktop.UDisks2',
                                        item,
                                        'org.freedesktop.UDisks2.Block',
                                        'Drive')
                       if drive == '/': continue

                       mountpoint = self.get_mountpoint(item)
                       if not mountpoint: continue
                       mountpoint = mountpoint.replace('\x00','')

                       drive = str(drive).split('/')[-1]
                       usage = self.get_mountpoint_usage(mountpoint)

                       part = str(item.split('/')[-1])
                       partitions.append((part,drive,mountpoint,usage))                       

            except Exception as e:
                #print(e)
                pass

        # returning list of tuples
        partitions.sort()
        return partitions

    def get_mountpoint(self,dev_path):
        try:
            data = self.get_dbus_property(
                             'system',
                             'org.freedesktop.UDisks2',
                             dev_path,
                             'org.freedesktop.UDisks2.Filesystem',
                             'MountPoints')[0]

        except Exception as e:
            #print(e)
            return None
        else:
            if len(data) > 0:
                return ''.join([ chr(byte) for byte in data])


    def get_unmounted_partitions(self):
        objects = self.get_dbus('system', 
                           'org.freedesktop.UDisks2', 
                           '/org/freedesktop/UDisks2', 
                           'org.freedesktop.DBus.ObjectManager',
                           'GetManagedObjects',
                           None)


        partitions = []
        for item in objects:
            try:
                if 'block_devices'  in str(item):
                       drive = self.get_dbus_property('system',
                                        'org.freedesktop.UDisks2',
                                        item,
                                        'org.freedesktop.UDisks2.Block',
                                        'Drive')
                       if drive == '/': continue

                       mountpoint = self.get_mountpoint(item)
                       if  mountpoint: continue

                       drive = str(drive).split('/')[-1]
                       part = str(item.split('/')[-1])
                       if not part[-1].isdigit(): continue
                       partitions.append((part,drive))                       
                       #print(partitions)

            except Exception as e:
                #print(e)
                pass

        partitions.sort()
        return partitions

    def get_dbus(self,bus_type,obj,path,interface,method,arg):
        if bus_type == "session":
            bus = dbus.SessionBus() 
        if bus_type == "system":
            bus = dbus.SystemBus()
        proxy = bus.get_object(obj,path)
        method = proxy.get_dbus_method(method,interface)
        if arg:
            return method(arg)
        else:
            return method()

    def get_dbus_property(self,bus_type,obj,path,iface,prop):

        if bus_type == "session":
           bus = dbus.SessionBus()
        if bus_type == "system":
           bus = dbus.SystemBus()
        proxy = bus.get_object(obj,path)
        aux = 'org.freedesktop.DBus.Properties'
        props_iface = dbus.Interface(proxy,aux)
        props = props_iface.Get(iface,prop)
        return props

    def make_alias(self,*args):
        partitions = [ i[0] for i in self.get_partitions() ]

        combo_values = '|'.join(partitions)
        #print(combo_values)
        command=[ 'zenity','--forms','--title','Make Alias',
                  '--add-combo','Partition','--combo-values',
                  combo_values,'--add-entry','Alias'    ]        
        user_input = self.run_cmd(command)
        if not user_input: return

        alias = user_input.decode().strip().split('|')

        existing_values = None

        if os.path.isfile(self.config_file):
            with open(self.config_file) as conf_file:
                try:
                    existing_values = json.load(conf_file)
                except ValueError:
                    pass


        with open(self.config_file,'w') as conf_file:
             if existing_values:
                 existing_values[alias[0]] = alias[1]
             else:
                 existing_values = {alias[0]:alias[1]}

             #print(existing_values)
             json.dump(existing_values,conf_file,indent=4,sort_keys=True)


    def find_alias(self,part):
        if os.path.isfile(self.config_file):
            with open(self.config_file) as conf_file:
                try:
                    aliases = json.load(conf_file)
                except ValueError:
                    pass
                else:
                    if part in aliases:
                       return aliases[part]
                    else:
                       return None

    def toggle_auto_startup(self,*args):
        user_home = os.path.expanduser('~')
        desktop_file = '.config/autostart/udisks-indicator.desktop'
        full_path = os.path.join(user_home,desktop_file)

        if os.path.exists(full_path):
           os.unlink(full_path)
        else:
           original = '/usr/share/applications/udisks-indicator.desktop'
           if os.path.exists(original):
               shutil.copyfile(original,full_path)

        self.make_menu()


    def open_mountpoint(self,*args):
        pid = subprocess.Popen(['xdg-open',args[-1]]).pid

    def open_disks_utility(self,*args):
        pid = subprocess.Popen(['gnome-disks']).pid

    def run_cmd(self, cmdlist):
        """ Reusable function for running external commands """
        new_env = dict(os.environ)
        new_env['LC_ALL'] = 'C'
        try:
            stdout = subprocess.check_output(cmdlist, env=new_env)
        except subprocess.CalledProcessError:
            pass
        else:
            if stdout:
                return stdout

    def run(self):
        """ Launches the indicator """
        try:
            gtk.main()
        except KeyboardInterrupt:
            pass

    def quit(self, data=None):
        """ closes indicator """
        gtk.main_quit()

def main():
    """ defines program entry point """
    indicator = UdisksIndicator()
    indicator.run()

if __name__ == '__main__':
    main()

The /usr/share/applications/udisks-indicator.desktop

[Desktop Entry]
Version=1.0
Name=Udisks Indicator
Comment=Indicator for reporting partition information
Exec=udisks-indicator
Type=Application
Icon=drive-harddisk-symbolic.svg
Terminal=false

Additional Info:

Ubuntu Mate 16.04 test:

enter image description here

Gnome users need an extension (KStatusNotifierItem/AppIndicator Support) to make the indicator behave properly:

enter image description here


Install Sysmonitor Indicator:

sudo add-apt-repository ppa:fossfreedom/indicator-sysmonitor
sudo apt-get update
sudo apt-get install indicator-sysmonitor

and it has "Available Space in File System" option.


There is another answer using basic Sysmonitor Indicator but you can create your own custom panel with as much information as you like.

Google (well search at least) is your friend

First step is to figure out how to calculate partition use percentage:

$ percentage=($(df -k --output=pcent /dev/sda1))
$ echo "${percentage[1]}"
13%

Create bash script to echo to panel

Here is a bash script to use as "custom" option in Sysmonitor Indicator. It will show the percentage used on the first three partitions on /dev/sda:

#!/bin/bash
echo "sda1: "
percentage=($(df -k --output=pcent /dev/sda1))
echo "${percentage[1]}"
echo " | sda2: "
percentage=($(df -k --output=pcent /dev/sda2))
echo "${percentage[1]}"
echo " | sda3: "
percentage=($(df -k --output=pcent /dev/sda3))
echo "${percentage[1]}"

Sample output

When running it will look like this:

indicator systmonitor example.png

Install and configure custom scripts in Sysmonitor Indicator

For detailed instructions on installing Sysmonitor Indicator and assigning a custom script see this answer: Can BASH display in systray as application indicator?