Tanguy Ortolo: Opportunistic SSH agent
To use an SSH agent, one usually has to:
- launch the agent;
- add his key to it.
To use an SSH agent, one usually has to:
To use an SSH agent, one usually has to:
To use an SSH agent, one usually has to:
Ben mentions he left Google Reader and went back to Liferea, but mentions a series of bugs that keep him from being happy. After pondering it a bit, a couple of months ago I also left Google Reader, but I turned to a free webapp: rssLounge aggregator. Although it does not fully cover Ben's wishlist (I'll get to it now), I am happy using it as it covers my main need: Being able to read my stuff from just about everywhere, without installing even a ssh client (that would make public Windows machines a liability for me, as they could sniff my keystrokes while authenticating to my ssh server). So, for me, a webapp is basically a must.
Well, as for Ben's list:
I switched from Google Reader to Liferea a while back. I was mostly
happy with the functionality of Reader but I don't really want my
reading history to be recorded or my feed list to be vulnerable to
the whim of Google's inscrutable abuse department.
I'm still using Liferea but unfortunately it has a lot of problems.
Yes I do have bug numbers:
During these days, there are various carnivals in Prague. On Saturday I've visited Malostransk masopust, which is probably not the biggest one, but definitely the one in most attractive location, starting at Prague castle and going down to Kampa.
This was actually my first visit of this carnival and I quite enjoyed it. Bellow you can find some photos taken during the event to catch the atmosphere:
Filed under: English Photography 0 comments Flattr this!
disk=/dev/foo
smartctl -a $disk
smartctl -t long $disk
badblocks -swo $vendor_$model_$serial_$timestamp.badblocks.swo $disk
smartctl -a $disk
Copyright maximalists, such as MPAA and RIAA, like to say that copyright
violations are theft. I don't agree, but if they are, then logically,
extending copyright in a way that makes things that were out of
copyright to again be in copyright is also theft. And that's happened
so much it's grand larceny.
thanks to the Paris
BSP & other activities we're seeing a nice decline in RC bugs. here
are my recent contributions:
That s sad. Hardware that was supported sometime ago, it s now unsupported. I've released version 0.25 of Obnam,
my backup application.
nagios-last-backup-age subcommand is useful for setting up Nagios
(or similar systems) to check that backups get run properly. Thanks to
Peter Palfrader for the patch.ssh-known-hosts (for choosing which file to check for
known host keys), strict-ssh-host-keys (for disallowing unknown host
keys), and ssh-key (for choosing which key file to use for SSH
connections) allow better and safer use of ssh.--pretend option now works for backups as well.obnam ls now shows the correct timestamps for generations.
Thanks, Anders Wirzenius.
<style type="text/css">
@import "/pub/special-css/venk.css";
</style>
Since 2002, groups of college students have undertaken a 70 day, 4000+ mile summer bike ride across the United States with the goal of offering hope, inspiration and support to cancer communities along the way. This past summer was our 10th year of cycling across the country as 76 volunteers rode along three different routes: Baltimore to San Francisco, Baltimore to Portland, and Baltimore to Seattle. Our riders raised a combined $476,000 to support organizations and individuals in the fight against cancer.His fundraising goal is $5,000. Anything from $5 to $500 is a donation to an organization that helps young adult cancer surviers and their families get access to information and support resources. Can you help?
When I told people of my plans to move to Montreal, it usually prompted one of two reactions: one was some version of joyful envy, many people exclaiming breathlessly Montreal is one of my favorite cities, one person once even clutching my arm and told me as he looked me straight in the eye: you are so lucky, there is no city quite like Montreal in North America.
The second reaction came off as a thinly veiled mixture of disdain and disbelief usually peppered with many reallys: oh wow, really, really you would really leave NYC? I am pretty certain they really were thinking something along the lines of what a fool, how dare she leave a great job, a great university, a world class city (the only city to live) for some Canadian mid-sized city, which is like tundra for a good chunk of the year?
The decision to move weighed heavily on me, if for no other reason I had a choice to stay or to go and I honestly have not had a choice, a decision to make about where to go since I got accepted to graduate school (and even then the choice was more obvious than this one). So over a month into my move what is my verdict? In a word, win.
I don t miss NYC at all though I get why some people cannot leave the place and know that despite some oddities and difficulties of living in Montreal, it fits my tastes and needs much better than NYC which dwarfed me in so many ways. I never felt I could enjoy it, I grew tired of the cramped living quarters, the noise ate at my soul, and I simply felt more overwhelmed by the fact that I could not even get a handle on the neighborhoods in my vicinity, much less all the other hoods in the area.
Instead of dogging NYC anymore, I think I will spend a little time on first impressions, as they will soon be lost to the familiarity borne with time and experience. In essence Montreal is chock full of life but rather intimate, a quirky city with lots of charm but some grit and lacking the way over designed and done feel of cities like Portland.
Here are some of quirks:
1. The Hawt Metro: I fell in love with the Metro when I first rode it a few years ago. I just love the powder blue color of the cars and the super sweet 1960s aesthetic of many stations. Even better and unlike NYC, they are just clean and quiet. The downside? The temperatures approximates a sauna during the winter and while you would think this is a good thing, when you are layered with the clothing necessary to survive outside (re: long underwear along with Canada-coat, gloves, hat, and scarf), it is hooooooot down there and you feel like you need to pass out.
2. Spend money, get free stuff: In many establishments you get free stuff (like blueberries or some like sports bar) when you spend over a certain amount of money, like 70 bucks. Quirky local tradition.
3. The culture of negotiation and the kick ass standard lease: Housing is amazing here. There is plenty of it, there are many different styles, and it is rather fun exploring all the different hoods that make up the city. Problem is too that lots of apartments have weird problems and issues and I had to steer clear of anything that could even possibly have mold. I spent weeks day in day out looking for a place, desperate to move out of my corporate apartment very nicely provided by the university but still not my ideal living situation. Finally found a place that fit all my needs in the perfect location and I took it to only find out that places are priced to negotiate and I was faced with the decision to negotiate or not. Sort of did, was not thrilled about it (thinking that I might lose the place) but it sort of worked and I scored the place. If price is up to haggling, the lease on the other hand, is standard (you can buy one at your local bodega ). It is the law to use it and it is like a no nonsense, straightforward lease, which is very protective of renters.
4. Montreal is known for its exceptional food but you know Poutine is just plain gross: Food here is good and I can tell that I will get a handle of restaurants in a way that felt impossible in NYC. The gluten free religion seems to be spreading, thankfully. There are many little Fruiterias! to get your fruits veggies which I am still exploring and right around my house is a crazy supermarket that is so cheap, which is weird because consumer goods generally ain t cheap in Montreal like they are in the states but this place is a gem and everyone agrees (and almost impossible to notice from the street!). Now Poutine is disgusting. Ok it did not help that the first night I went out to eat it, I was still under the clutches of Noro virus, and I think it re-activated the nausea that had been zapped by some strong medicine and the hospital, the day before, which brings me to the next point, the health care system.
5. Healthcare, I had to use it way too early: So last week I came down with the Noro virus and you usually wait it out as it runs through you quickly but I was dehydrated before I even started to vomit to for 8 hours straight, at which point severely tired and so nauseous (I was yelling to make it stop), I went to the hospital. Now I had talked to lot of people about the healthcare system in Montreal as it seems good, really great but a bit over taxed, especially compared to where I had lived in Edmonton where it was like a magic fairy tale dream. I had heard of two things: the care is excellent but the facilities are shocking and the wait times unless dire can be atrociously long. So facilities, yea they are kinda shocking, somewhat shabby but who cares, so long as the care is good, no? Packaging is irrelevant so long as the goods are derived. Before going I was scared of the long wait times (and also the taxi took me by mistake to Montreal General Hospital was looked too much like a HUGE version of the creepy buildings in The Shining for me, and I was supposed to go to Jewish General so left for there). The wait time: nearly none, somewhat as shocking as the facilities first looked to me. I think it was a combination of the time I arrived, with the fact that my lounge was parched and yellowish-gross (sorry, it was gross), indicating I was dehydrated, oh and I was crying bit hysterically, for despite my high threshold for pain, nausea terrorizes me. I was covered by insurance and since I did not yet have my McGill health cards (it takes three months to qualify for the local stuff), I did pay and the price was laughably cheap compared to what I would pay in NYC for the same treatment.
6. Now for my favorite, snow so nice, ice oh Christ: Well this winter has been, by all accounts, weak and warm, the spirit of winter barely making its way from the underworld to the outerworld. But even though it is has been more idle than full throttle, I still got a pretty accurate taste of what winter is like, with a few days of 20- c temps, and having to walk a number of times on a layer of frozen ice that makes it feel like a very dangerous mini-ice age in the making.
I do rather love the quiet snow falling and just love love sprinting through the snow with my dog, Roscoe, who has taken a liking for prancing in the white stuff and looks awful cute with his winter man s ice beard. After a sizable snowfall, it is clear they city does not toy with the snow removal although the sidewalk snow plows do look somewhat like very large and dangerous but kinda cute toys. But let s be frank, winters are hard, so hard that I think I would go mad if I had to stay through the entire thing, being born and raised in the tropics So the fact that I am writing this from the southern hemisphere in the height of summer gives me the assurance I can handle the rest of the snow, ice, ice and snow upon my return.
debian-policy package.
Input data are the debian/copyright files of all
Debian source packages. If license-count is not
bugged, our debian/copyright files might be. One thing
that occurred to me only a few days ago is the habit of
declaring a different license for Debian packaging (the
files under debian/) than the software being packaged
itself. That's a bad habit because it might cause unwanted license
mixtures via patches that live under debian/ but I've
seen several occurrences of it in the Debian archive. For name and
(self-)shame: I've also been guilty of it in the past, when I
was young .
Is that reason enough to skew results and overestimate
GPL-d software? I don't think so, I hope not, but
ultimately I don't know. It'd be nice to rule out the possibility
entirely. So if anyone is willing to do some sampling of affected
debian/copyright files and propose patches for
license-count to exclude those "false positives",
please shout. (As a bonus point: that would also help to take more
sound decision for the typical use case of
license-count, i.e. deciding when a license should be
added to /usr/share/common-licenses.)
Other independent reviews of the results are equally
welcome.
Note: the above, as well as John's analysis, would be a trivial
exercise if DEP-5
were already widely deployed in the Debian archive.
license-count, posted a
way more likely cause of data skew in John's analysis: double
counting among the different types of copyleft licenses
The new RcppArmadillo release 0.2.35 now
supports the Rcpp::Rcout output stream device. Based on a contributed
Rcpp patch by Jelper Ypma, the
Rcpp::Rcout output stream gets redirected to R's buffered output. In other words, R's own output and that
eminating from C++ code using Rcpp::Rcout are now both in sync. This avoids a stern warning
from Section 5.6 in the Writing R Extensions manual:
Using C++ iostreams, as in this example, is best avoided. There is no guarantee that the output will appear in the R console, and indeed it will not on the R for Windows console. Use R code or the C entry points (*note Printing) for all I/O if at all possible.and does in fact provide exactly what is recommended: the same entry points R itself uses. Below is a sample program, once again using the wonderful inline package to compile, load and link C++ code into R from a simple text variable submitted to the
cxxfunction.
What is shown in R code to load the package, the definition of the C++ code as assigned to a variable src
and the creation of the dynamically-loadaded R function called fun which contains the code from we
compiled, link and load via a single call to cxxfunction() given src.
We then switch to a temporary directory (as the example code, taken from one of the two examples in Conrad's Armadillo sources, creates a temporary file) and run the new function. To demontrate how it does in fact now mesh perfectly with R, we create an output 'sink' (which catches all output) and re-run. This simple example demonstrated how we can use the newlibrary library(inline) src <- ' Rcpp::Rcout << "Armadillo version: " << arma::arma_version::as_string() << std::endl; // directly specify the matrix size (elements are uninitialised) arma::mat A(2,3); // .n_rows = number of rows (read only) // .n_cols = number of columns (read only) Rcpp::Rcout << "A.n_rows = " << A.n_rows << std::endl; Rcpp::Rcout << "A.n_cols = " << A.n_cols << std::endl; // directly access an element (indexing starts at 0) A(1,2) = 456.0; A.print("A:"); // scalars are treated as a 1x1 matrix, // hence the code below will set A to have a size of 1x1 A = 5.0; A.print("A:"); // if you want a matrix with all elements set to a particular value // the .fill() member function can be used A.set_size(3,3); A.fill(5.0); A.print("A:"); arma::mat B; // endr indicates "end of row" B << 0.555950 << 0.274690 << 0.540605 << 0.798938 << arma::endr << 0.108929 << 0.830123 << 0.891726 << 0.895283 << arma::endr << 0.948014 << 0.973234 << 0.216504 << 0.883152 << arma::endr << 0.023787 << 0.675382 << 0.231751 << 0.450332 << arma::endr; // print to the cout stream // with an optional string before the contents of the matrix B.print("B:"); // the << operator can also be used to print the matrix // to an arbitrary stream (cout in this case) Rcpp::Rcout << "B:" << std::endl << B << std::endl; // save to disk B.save("B.txt", arma::raw_ascii); // load from disk arma::mat C; C.load("B.txt"); C += 2.0 * B; C.print("C:"); // submatrix types: // // .submat(first_row, first_column, last_row, last_column) // .row(row_number) // .col(column_number) // .cols(first_column, last_column) // .rows(first_row, last_row) Rcpp::Rcout << "C.submat(0,0,3,1) =" << std::endl; Rcpp::Rcout << C.submat(0,0,3,1) << std::endl; // generate the identity matrix arma::mat D = arma::eye<arma::mat>(4,4); D.submat(0,0,3,1) = C.cols(1,2); D.print("D:"); // transpose Rcpp::Rcout << "trans(B) =" << std::endl; Rcpp::Rcout << trans(B) << std::endl; // maximum from each column (traverse along rows) Rcpp::Rcout << "max(B) =" << std::endl; Rcpp::Rcout << max(B) << std::endl; // maximum from each row (traverse along columns) Rcpp::Rcout << "max(B,1) =" << std::endl; Rcpp::Rcout << max(B,1) << std::endl; // maximum value in B Rcpp::Rcout << "max(max(B)) = " << max(max(B)) << std::endl; // sum of each column (traverse along rows) Rcpp::Rcout << "sum(B) =" << std::endl; Rcpp::Rcout << sum(B) << std::endl; // sum of each row (traverse along columns) Rcpp::Rcout << "sum(B,1) =" << std::endl; Rcpp::Rcout << sum(B,1) << std::endl; // sum of all elements Rcpp::Rcout << "sum(sum(B)) = " << sum(sum(B)) << std::endl; Rcpp::Rcout << "accu(B) = " << accu(B) << std::endl; // trace = sum along diagonal Rcpp::Rcout << "trace(B) = " << trace(B) << std::endl; Rcpp::Rcout << std::endl; 'fun <- cxxfunction(signature(), body=src, plugin="RcppArmadillo") setwd("/tmp") # adjust on other OSs fun() # output to stdout sink("rcpparma.log.txt") # start 'sink' to output to file fun() # no output to screen sink() # stop 'sink'
Rcout output stream from
Rcpp to have dynamically-loaded C++ code cooperate more
cleanly with the (buffered) R output. It also demontrated some of the nice features in Armadillo
which we bring to R via RcppArmadillo.
While improving GNOME s servers Nagios Notifications, I ended up working on a nice way to notify the relevant folks through GTalk in case something could go wrong on any of the hosted services. Looking around on the web, I found Seth Vidal s script, modified it to suit my needs and made it working with GTalk, here s the result:
#!/usr/bin/python -tt
import warnings
warnings.simplefilter("ignore")
import xmpp
from xmpp.protocol import Message
from optparse import OptionParser
import ConfigParser
import sys
import os
parser = OptionParser()
opts, args = parser.parse_args()
if len(args) < 1:
print "xmppsend message [to whom, multiple args]"
sys.exit(1)
msg = args[0]
msg = msg.replace('\\n', '\n')
# Connect to the server
c = xmpp.Client('gmail.com')
c.connect( ( 'talk.google.com', 5223 ) )
# Authenticate to the server
jid = xmpp.protocol.JID( 'example@gmail.com' )
c.auth( jid.getNode( ), 'yourgmailpassword' )
if len(args) < 2:
r = c.getRoster()
for user in r.keys():
if user == username:
continue
c.send(Message(user, '%s' % msg))
else:
for user in args[1:]:
c.send(Message(user, '%s' % msg))
I, then, added the command definitions on the relevant Nagios configuration file:
define command
command_name host-notify-by-xmpp
command_line /home/user/bin/xmppsend "Host '$HOSTALIAS$' is $HOSTSTATE$ - Info : $HOSTOUTPUT$" $CONTACTPAGER$
define command
command_name notify-by-xmpp
command_line /home/user/bin/xmppsend "$NOTIFICATIONTYPE$ $HOSTNAME$ $SERVICEDESC$ $SERVICESTATE$ $SERVICEOUTPUT$ $LONGDATETIME$" $CONTACTPAGER$
And in the end on contacts.cfg:
define contact
contact_name admin
use generic-contact
alias Full Name
email example@gmail.com
pager example@gmail.com
service_notification_commands notify-by-xmpp
host_notification_commands host-notify-by-xmpp
When done just reload the configuration files with:
sudo /etc/init.d/nagios3 reloadEnjoy your new XMPP Nagios notifications! Update: if you don t want the script to store your username or password, you can use the following modified script together with a nice config file like this one:
[xmpp_nagios] username=example@gmail.com password=yourgmailpasswordThen you can invoke xmppsend this way:
xmppsend -a config.ini
We needed a new package at work and once I'd written it, I realised that it could well be useful for others, so I did the ITP and the package is now in Debian unstable.
Ladder creates a local repository of packages required
to upgrade a tarball of a chroot to a new milestone or
software release.
.
The repository can be signed and includes all specified
target packages and dependencies. The repository can then
be distributed and used to upgrade multiple devices in
sequence without needing network access.
const char *foo = "foo";foo is a constant. It is a pointer to a constant. In practical ELF terms, this means the pointer lives in the .data section, and the string constant in .rodata. The following code defines a constant pointer to a constant:
const char * const foo = "foo";.rodata. But keeping a constant pointer to a constant string is pointless. In the above examples, the string itself is 4 bytes (3 characters and a zero termination). On 32-bits architectures, a pointer is 4 bytes, so storing the pointer and the string takes 8 bytes. A 100% overhead. On 64-bits architectures, a pointer is 8 bytes, putting the total weight at 12 bytes, a 200% overhead.
The overhead is always the same size, though, so the longer the string, the smaller the overhead, relatively to the string size.
But there is another, not well known, hidden overhead: relocations. When loading a library in memory, its base address varies depending on how many other libraries were loaded beforehand, or depending on the use of address space layout randomization (ASLR). This also applies to programs built as position independent executables (PIE). For pointers embedded in the library or program image to point to the appropriate place, they need to be adjusted to the base address where the program or library is loaded. This process is called relocation.
The relocation process requires information which is stored in .rel.* or .rela.* ELF sections. Each pointer needs one relocation. The relocation overhead varies depending on the relocation type and the architecture. REL relocations use 2 words, and RELA relocations use 3 words, where a word is 4 bytes on 32-bits architectures and 8 bytes on 64-bits architectures.
On x86 and ARM, to mention the most popular 32-bits architectures nowadays, REL relocations are used, which makes a relocation weigh 8 bytes. This puts the pointer overhead for our example string to 12 bytes, or 300% of the string size.
On x86-64, RELA relocations are used, making a relocation weigh 24 bytes! This puts the pointer overhead for our example string to 32 bytes, or 800% of the string size!
Another hidden cost of using a pointer to a constant is that every time it is used in the code, there will be pointer dereference. A function as simple as
int bar() return foo; foo is defined const char *. On x86, that instruction weighs 2 bytes. On x86-64, 3 bytes. On ARM, 4 bytes (or 2 in Thumb). That weight can vary depending on the additional instructions required, but you get the idea: using a pointer to a constant also adds overhead to the code, both in time and space. Also, if the string is defined as a constant instead of being used as a literal in the code, chances are it s used several times, multiplying the number of such instructions. Update: Note that in the case of const char * const, the compiler will optimize these instruction and avoid reading the pointer, since it s never going to change.
The symbol for foo is also exported, making it available from other libraries or programs, which might not be required, but also adds its own overhead: an entry in the symbols table (5 words), an entry in the string table for the symbol name (strlen("foo") + 1) and an entry in the symbols hash chain table (4 bytes if only one type of hash table (sysv or GNU) is present, 8 if both are present), and possibly an entry in the symbols hash bucket table, depending on the other exported symbols (4 or 8 bytes, as chain table). It can also affect the size of the bloom filter table in the GNU symbol hash table.
So here we are, with a seemingly tiny 3 character string possibly taking 64 bytes or more! Now imagine what happens when you have an array of such tiny strings. This also doesn t only apply to strings, it applies to any kind of global pointer to constants.
In conclusion, using a definition like
const char *foo = "foo";const char foo[] = "foo";static const char foo[] = "foo";__attribute__((visibility("hidden"))) const char foo[] = "foo";Next.