Pondus: A personal weight management software

A week after my return from a New England & Canada cruise, I found myself busy searching for a personal weight management software.

Why weight management? See the chocolate dessert buffet pictures taken on board the Holland America Maasdam cruise ship.

I came across pondus, a python program that is free and open-sourced.

Pondus has a rather modest feature set: the ability to enter one's weight over time, and have it plotted in a chart. It does not have too many bells and whistles, but it is very simple to use.

Pondus is packaged with certain Debian releases (namely, Lenny and Sid). So a simple apt-get install pondus will put it on your system. Because I run Debian Etch, I need to install it from source files.

I downloaded the source tar ball as well as the install instructions from here. The instructions are straight-forward, and I installed pondus without a glitch.

To run pondus, just type pondus in the command line. When you run pondus for the first time, it is not too terribly exciting .... because you have not entered any weight data.

Before you enter your weight, you should customize the unit of measure that pondus will use(lbs versus kgs). Click on the Tool icon (the one with the screwdriver and wrench) to bring up Preferences. For me, I prefer pounds (that is the unit my scale uses).

Now, let's enter some weight data, and draw a pretty chart.

To enter a weight, click on the Plus icon.

To plot the data, click on the Chart icon.

Pondus has some additional useful features such as data import and export in CSV format, as well as the ability to save the chart in png or svg (2-dimensional vector graphics) format.

An interesting feature is that you can set time-sensitive goals (aka, Weight Planner). For example, you can set a goal such as "weigh 180 lbs on August 15". This feature is disabled by default. To enable it, bring up Preferences as above, and click Use Weight Planner checkbox to select it, and choose whether to include the weight plan in your plots. Note that this feature is not for everyone (do I really need yet another remainder of my shortcomings?)

Pondus is adequate for tracking my body weight. I'm still searching for software that can also track my blood pressure. Won't it be perfect if a single software can manage both weight and blood pressure?

How to do reverse DNS lookup

Most people can better remember domain names, e.g., www.gnu.org, than their corresponding IP addresses, 199.232.41.10. (In this example, www.gnu.org is the home of the Free Software Foundation.) We delegate the responsibility to machines, aka, the DNS servers, to resolve the domain names for us.

Sometimes, we do need to manually lookup the IP address of a domain name. You may already be familiar with the nslookup command which is now deprecated. We use the dig command to make DNS queries.

 $ dig +noall +answer www.gnu.org
www.gnu.org.            67      IN      CNAME   gnu.org.
gnu.org.                67      IN      A       199.232.41.10

The IP address is displayed in the A record, and is 199.232.41.10.

The +noall, +answer combination basically tells dig to only report the answer of the DNS query and skip the rest of the output.

You can also use the dig command with the -x option to do a reverse DNS lookup. A reverse DNS lookup means you want to look up the domain and host name of an IP address.

 $ dig +noall +answer -x 199.232.41.10
10.41.232.199.in-addr.arpa. 36000 IN    CNAME   rev-c41-10.gnu.org.
rev-c41-10.gnu.org.       300     IN      PTR     www.gnu.org.

The PTR record is the one that contains the domain host name. The domain name is, as you expect, www.gnu.org.

Note that PTR records are not required for IP addresses. If a PTR record is not defined for an IP address, you cannot do a remote DNS lookup.

How to count number of files in a directory

Now that I am back from vacation, I had to take care of some chores, like uploading the pictures taken with my digital camera.

I stepped out during the long upload process (400+ pictures). When I returned, it was already done. To just make sure all pictures are now on the server, I wanted to count the number of files in the targetdir directory.

$ ls -1 targetdir | wc -l
454

The above command reads ls dash one piped to wc dash letter l.

Note that if you had used ls dash letter l instead, the count is one greater than the actual number of files. This is because ls dash letter l outputs an extra total line:

$ ls -1 targetdir 
total 529436
-rw-r--r-- 1 peter peter  1510976 Jul 13  2008 DSCN1001.jpg
....

The above method will count symbolic links as well as subdirectories in targetdir (but not recursively into subdirectories).

If you want to exclude subdirectories, you need a heavier duty tool than ls.

$ find targetdir -maxdepth 1 -type f | wc -l

-type f ensures that the find command only returns regular files for counting (no subdirectories).

By default, the find command traverses into subdirectories for searching. -maxdepth 1 prevents find from traversing into subdirectories. If you do want to count files in the subdirectories, just remove -maxdepth 1 from the command line.

Note that the find command does NOT classify a symbolic link as a regular file. Therefore, the above find -type f command does not return symbolic links. As a result, the final count excludes all symbolic links.

To include symbolic links, add the -follow option to find.

$ find targetdir -follow  -maxdepth 1 -type f | wc -l 

Dual pane Linux file managers: mc and emelfm

I have been computing all my life without using a dual pane file manager until one day I decided that having one will greatly enhance my qualify of life. What I had in mind was something that will make my life easier in the copying or moving of files from 1 directory to another.

By dual pane (or twin-pane) file manager, I mean a file manager that displays two directories side by side (one active, one passive). The term is confusing because often a dual pane file manager has a third pane that lets you enter commands to execute on the active directory.

Staying true to my preference for Command Line Interface (CLI), I first tried Midnight Commander (mc). As advertised, mc is a file manager that is loaded with features. What I am looking for though is modest: a file manager with 2 directory panes that will satisfy my very basic day-to-day file management needs.


I found myself customizing the look and feel of mc in the early adoption stage. The nostalgic white text on blue background had to go.

You can run mc with the -b option to force black and white.
$ mc -b

If you don't want to go that far, you can customize the color used by editing the init file (~/.mc/ini).

I inserted the following lines into the ~/.mc/ini file.

[Colors]
base_color=lightgray,green:normal=green,default:selected=white,gray:marked=yellow,default:markselect=yellow,gray:directory=blue,default:executable=brightgreen,default:link=cyan,default:device=brightmagenta,default:special=lightgray,default:errors=red,default:reverse=green,default:gauge=green,default:input=white,gray:dnormal=green,gray:dfocus=brightgreen,gray:dhotnormal=cyan,gray:dhotfocus=brightcyan,gray:menu=green,default:menuhot=cyan,default:menusel=green,gray:menuhotsel=cyan,default:helpnormal=cyan,default:editnormal=green,default:editbold=blue,default:editmarked=gray,blue:stalelink=red,default

I also rearranged the panes so that they are placed horizontally (instead of vertically). You can interactively customize the placement using the mc Options menu (when you are already in mc). Alternatively, you can edit the ~/.mc/ini file, and make sure that the following horizontal_split line appears in the [Midnight-Commander] section:
[Midnight-Commander]
....
horizontal_split=1

My mc window looked like this after the above customization.


Another major annoyance is that if you run mc in a Gnome window, you cannot use the F10 key to quit mc. It turns out that F10 is normally the key to access the menu-bar in Gnome. To quit mc, you use your mouse to click the Quit soft-key.

If it bothers you as much as it bothered me, you might want to disable the standard F10 menu-bar shortcut key for Gnome. To do that:
$ gconftool-2 --set /apps/gnome-terminal/global/use_menu_accelerators --type bool false

After giving it a good run for about 3 weeks, I gave up on mc. The determining factor was how mc handles the Tab key.

Like other dual pane file managers, mc has a third pane that acts as the command line input window. However, the type of commands that will run in that window seems very limited. I tried commands such as date, pwd, ls, but they all showed no output. The most annoying feature to me is the Tab key. I am used to tapping the Tab key in a bash window for command completion. If you hit Tab while you are typing away in the mc's command line window, the effect is that mc switches the active focus to the other pane.

I won't be surprised if someone tells me there is a way to customize the handling of the Tab key. But, at that point in time, I concluded that I will look for some other file manager that requires less adjustment and customization.

I first became aware of emelfm because it is packaged with the Damn Small Linux (DSL) distribution. I decided to take a look at it because if it is included in DSL, it should be simple enough to satisfy my modest needs.

emelfm is a GUI-based double pane file manager. It has a clean, simple, and intuitive UI. It does the basic file copying and moving. It also has some nice additional features such as the ability to set bookmarks and apply filters to filenames.

One minor annoyance I find is when I try to copy a file in the active window to the same location. Essentially, what I want to do is copy and paste a file (to a new name) in the same directory in the active pane. I cannot use the Copy button to do it because it will only copy the file to the other pane. Instead, I need to enter the cp command explicitly in emelfm's command line window to do the copy.

[P. Evans pointed out that emelfm has a Clone plugin that copies a file to the same directory. Click Configure and then Buttons. Add a button and select the Clone plugin.]

Using the command line window in emelfm turns out to be a pleasant experience (as compared to mc). Hitting the Tab key will only switch the active pane if your mouse cursor is not in the command line window. If the cursor is in the command line window, hitting the Tab key does what I expect: command and filename completion. The commands that did not work in mc all worked well in emelfm (date, pwd, ls).

I have been happily using emelfm since then. There are other GUI-based dual pane file managers out there: e.g., Krusader, Double Commander. I have not tried them. However, I do most file management on the CLI, and only occasionally use a GUI-based file manager to do file copying. As such, emelfm satisfies my requirement for a GUI-based file manager.

Run emacs in batch mode to byte-compile elisp files

emacs is my favorite text editor. (No flame please.)

Little known and used perhaps is the fact that emacs does run in batch mode. By batch, I mean emacs accepts and executes commands in the command line, without any user interaction.

You can emulate a typical emacs text editing session as follow:
$ emacs -batch afile.txt -l runme.el -f save-buffer -kill

This command opens the afile.txt in batch emacs mode.

The -l parameter specifies an elisp file to load and execute. In this example, it loads the elisp file named runme.el which modifies the file buffer.

Next, it saves the buffer. Note that the -f parameter tells emacs to run a command, save-buffer in this case.

Finally, the -kill tells emacs to exit.

Below, I run emacs in batch to byte-compile a list of source elisp files. This comes in handy if you have a lot of source elisp files to compile.

$ emacs -batch -l runme.el -kill

Note that I do not need to save the buffer. Hence, no save-buffer.

The output byte-code files (.elc) will be put in the same directory as the source elisp files.

The runme.el file contains the commands to byte-compile the source elisp files.
$ cat runme.el
(byte-compile-file "/home/peter/emacs/mods/log4j-mode.el")
(byte-compile-file "/home/peter/emacs/mods/vm-w3m.el")