Syncthing install on CentOS 7.5

screenshot-720I will start by quoting the product. What is syncthing? “Syncthing is an application that lets you synchronize your files across multiple devices. This means the creation, modification or deletion of files on one machine will automatically be replicated to your other devices.” This says it all. Next question is: What for? This can vary: I’m going to say here because it’s  multi-platform: there are apps, a web interface, a GUI, and so on, and all of if for free. Unfortunately installing it on CentOS is not for newbies. Let’s start.

Step one: create a yum repository. There’s an entry abut syncthing on the centos forum. It means to create a special repository for syncthing. What I did is I copied an already existing repository, rename it, and edit it.

cd /etc/yum.repos.d/
cp epel.repo syncthing.repo
gedit syncthing.repo

Inside the edited repo file, we copy this. Then yum clean all, yum update. Or even better, reboot if you can. At the end

yum install syncthing
systemctl stop firewalld

And if you have the browser open, the Syncthing web UI as above will open. Now what? We go to the syncthing configuration, and we edit it so that it has my CentOS client IP, not the default one.  We may want to create a service for the process, but I’m not going to tell you how to do that.

I test that I can access to the web UI from another computer, and I can. Then I install the syncthing android app (that runs on the same network than my syncthing web server) and add the device on the web interface. It’s not very intuitive: to add the device you get a QR code or a very long set of letters and numbers.  Anyway, once I add it, I see on the web UI that syncthing wants to add one of the folders of my phone to the “Folders” section. I click “it’s OK” and the sync begins. Once you are done, you have the typical options: Pause, Rescan, Edit…

I must say the final sensation is very good, so I approve it. The problem will be, as usual, to propagate and promote its usage. We’ll see how it goes!


CryoSPARC not starting after update to v2.8 on CentOS 7.X : bad timing interval

As usual, click here if you want to know what is cryosparc. I have created a cryosparc master-client setup. In principle I did update from v2.5 to v.2.8 successfully after running on a shell cryosparc update. It’s the standard procedure. I got updated all, master and clients. But after the update I rebooted everything. And after the reboot of the master node the problems started. This is the symptom:

cryosparcm start
Starting cryoSPARC System master process..
CryoSPARC is not already running.
database: started
command_core: started

And the starting hangs there. The message telling you  where to go to access to your server is not appearing. Of course I waited. The status looks like this:

cryosparcm status
CryoSPARC System master node installed at
Current cryoSPARC version: v2.8.0
cryosparcm process status:
command_core                     STARTING 
command_proxy                    STOPPED   Not started
command_vis                      STOPPED   Not started
database                         RUNNING   pid 49777, uptime XX
watchdog_dev                     STOPPED   Not started
webapp                           STOPPED   Not started
webapp_dev                       STOPPED   Not started
global config variables:
export CRYOSPARC_DB_PATH="/XXX/cryosparc_database"

It looks like in this cryosparc forum post. Unfortunately no solution is given there. We can check what the log webapp is telling also:

 cryosparcm log webapp
    at listenInCluster (net.js:1392:12)
    at doListen (net.js:1501:7)
    at _combinedTickCallback (XXX/next_tick.js:141:11)
    at process._tickDomainCallback (XXX/next_tick.js:218:9)
cryoSPARC v2
Ready to serve GridFS
      throw er; // Unhandled 'error' event
Error: listen EADDRINUSE
    at Object._errnoException (util.js:1022:11)
    at _exceptionWithHostPort (util.js:1044:20)
    at Server.setupListenHandle [as _listen2] (net.js:1351:14)
    at listenInCluster (net.js:1392:12)
    at doListen (net.js:1501:7)
    at _combinedTickCallback (XXX/next_tick.js:141:11)
    at process._tickDomainCallback (XXX/next_tick.js:218:9)

It looks like a java problem (EADDRINUSE stands for address in use). So which java process is creating the listening error?

I clean up as suggested on this cryosparc post,  or on this one, deleting the /tmp/ and trying to find and kill any supervisord rogue process. That I don’t have. Next I reboot the master but the problem persists. Messing up with the MongoDB does not help also. What now? The cryosparc update installed a new python, so I decide to force the reinstall of the dependencies. It is done like this:

cryosparcm forcedeps
  Checking dependencies... 
  Forcing dependencies to be reinstalled...
  Installing anaconda python...
..bla bla bla...
 Forcing reinstall for dependency mongodb...
  mongodb 3.4.10 installation successful.
  Completed dependency check. 

If I believe what the software tells me, everything is fine. I reboot and run cryosparcm start but my “command core” still hangs on STARTING. After several hours of investigation, I decide to take a drastic solution. Install everything again. Then I find it.

 ./ --license $LICENSE_ID \
--hostname \
--dbpath /my-cs-database/cryosparc_database \
--port 39000
ping: bad timing interval
Error: Could not ping

What is this bad timing interval? I access to my servers via SSH + VPN, so it could be that the installer can’t handle the I/O of such a load, or the time servers we use, or something. Or maybe is that the Java versions differ? In any case, I approach to it on another way. I need to be closer. How to?

I open a virtual desktop there and in it, I call an ubuntu shell where I run my installer. Et voila! bad timing gone. And the install goes on without any further issues. Note that I do a new install using the previous database (–dbpath /my-cs-database/cryosparc_database so that everything, even my users, are the same than before 🙂

Long story short: shells may look the same but behave differently. Be warned!

Perl to Python, shell to perl, python to C : about code converters

First you need to have the need to convert the code. Why to convert a piece of code from one language to another? I going to name a few reasons:

  • Familiarity. Let’s say you are just a lamer, and yiu know by heart only python, C, or FORTRAN, and you get your code on another language you are not fully fluent. You can run a converter, then check the output on the language you control.
  • Integrability. The algorithm, the function, or whatever it is, needs to come together with other pieces, written on that “other” language. Although of course it it possible to have some kind of suite written in several languages, everything is more readable and beautiful if it’s under a common grammar.
  • Portability. A lot of operative systems have shells, or something very similar or compatible. We can’t say the same of python and perl, although if you are a good programmer you could install the interpreter you need beforehand. Like if you need an specific python to run your script.
  • Speed. Speed? Yes, speed. The same compiled code for simulation running on C++ may take 10 times less running as a FORTRAN compilation. I don’t have the numbers for python versus R, but definitely, some solutions are better than others.

I say convert, not translate, since what I want is the functionality. I got a piece of perl code of unknown value that I plan to use from a bash shell. As a first step, I want to translate it. So I google about it. I found this sh2p code. It does the opposite of what I want (shell to perl) but let’s install it. To do so,

# > perl Makefile.PL 
Checking if your kit is complete...
Looks good
Writing Makefile for App::sh2p
Writing MYMETA.yml and MYMETA.json

Now we make it

# > make
cp lib/App/sh2p/ blib/lib/App/sh2p/
...some more here
cp bin/ blib/script/
/usr/bin/perl -MExtUtils::MY -e 
'MY->fixin(shift)' -- blib/script/
Manifying blib/man3/App::sh2p::Builtins.3pm
Manifying blib/man3/App::sh2p::Handlers.3pm
Manifying blib/man3/App::sh2p.3pm
Manifying blib/man3/App::sh2p::Trap.3pm

And they ask us to run a test also like this:

# > make test

PERL_DL_NONLAZY=1 /usr/bin/perl 
"-MExtUtils::Command::MM" "-e" 
"test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/App-sh2p.t .. ok 
All tests successful.
Files=1, Tests=10, 0 wallclock secs 
( 0.03 usr 0.01 sys + 0.06 cusr 0.01 csys = 0.11 CPU)
Result: PASS

Finally we install it:

make install
Installing /usr/local/share/perl5/App/sh2p.pod
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/perl5/App/sh2p/
Installing /usr/local/share/man/man3/App::sh2p::Handlers.3pm
Installing /usr/local/share/man/man3/App::sh2p::Trap.3pm
Installing /usr/local/share/man/man3/App::sh2p::Builtins.3pm
Installing /usr/local/share/man/man3/App::sh2p.3pm
Installing /usr/local/bin/
Appending installation info to /usr/lib64/perl5/perllocal.pod

MY test run (on a CentOS 7 client):

# **** INSPECT: sleep replaced by Perl built-in sleep
# Check arguments and return value

And everything seems to be correct. Nice! We have a working shell to perl translator. How about the other way around? I didn’t find anything, but there is one perl to python translator on this github repo. I clone it, download it, whatever, and I run it over the perl script I just created ( , but the results are meaningless.

Let’s check more translations. How about making an executable with pp? No, it doesn’t seem to work. But this web here seems to do the trick. Even to C,C++ and with incomplete parts. I can now cut and copy what I want into my new project! And…that’s it for today, have a nice weekend!

LLDP Link Level Discovery Protocol on Windows and Linux

ldwinI need to know where are my computers connected without running around in the building, checking cables and reading not-so-easy-to-read cryptic labels. I’m not Central IT, so I don’t have access to the core switches. What can I do? First I build a list of Linux clients, like client01…client10, and Windows Clients. On then, I install the package lldpd. For CentOS 7.X, it is done like this:

yum install lldpd
systemctl enable lldpd.service 
systemctl start lldpd.service

You can now try it. For example I will show the neighbours:

root@client01 # lldpcli show neighbors
LLDP neighbors:
Interface: enXXX, via: LLDP, RID: 2, Time: YYY
ChassisID: mac AA:BB:CC:DD:EE:FF
SysDescr: My-Swit-Model-With-SW-Version
TTL: 120
MgmtIP: 111.222.333.444
Capability: Bridge, on
PortID: ifname 1
PortDescr: TP-1

Obviously I edited the output. We can grep the output, for example, on a for loop to get the SysName or PortDescr, once we are familiar with the ouput. What about Windows? For Windows, we can install the program above. You can find it here. By the way, the screen capture is from the blog entry. Now time to assemble the output on a web. Because I love web pannels 😀

Checksel ipmiutil warning on CentOS 7

I get from time to time this Warning:


WARNING: free space is low (=3184), need to clear with -d
ipmiutil sel version 3.12
-- BMC version 2.61, IPMI version 2.0 
SEL Ver 51 Support 02, Size = 1024 records (Used=825, Free=199)
ClearSEL: Log Cleared successfully
ipmiutil sel, completed successfully

I do have remote ILO access setup for this machine. As you see, the error is sorted out on its own, so no need to clear the ILO free space as suggested. For the records, there is a cron process called checksel. We can read it out:

 more /etc/cron.daily/checksel 
# This script runs ipmiutil sel writing any new records to syslog, 
# and will then clear the SEL if free space is low.

So we could, in principle, modify the cron to do whatever we want. Of course, I will not. I’m not very successful modifying things that work. I just wanted to log its existence 🙂

The Huawei incident

I’m a multi-platform user by need. So I can’t call myself an Android, an OSX or a Windows user. Of course, all of that said with the big mouth, without specifying any device. And of course I have my favourites. I must say I’m lucky I don’t have an Huawei terminal, or any of their clones (Honor and similar). But the big news of today about Google ending its deal with the technology firm Huawei sound like good news for me. I’ll try to explain why.

Previously I managed to install Android on my old DELL netbook just to find out the specs of it are way below my current mobile phone, to the point of looking ridiculous. But it worked. The install was quite easy, being the most complicated step to mount Oreo on a pen drive.

I do have a micro USB to USB adapter, and I do frequently read an USB with my generic handy. So why not let the users to install custom-designed ROMs on a handy, without the hassle of breaking the warranty or rooting the phone? In this way, I could, let’s say, install Windows XP on it, or something like that, if needed. I consider myself a pro, and I did brick an HTC already trying to root it.

If a company like Huawei goes ahead and let the people use their terminals whatever way you like (of course under certain circumstances, maybe after registering it as a test device, providing a valid email address, opening a developer’s profile with the company, or something like that) I think we will all be more free. I’m looking forward to be able to have a smartphone the way I like it, like one you can control what you send back home or not, or the apps you get and what they say. And maybe in that near future, I will finally have CentOS on my handy, if I need it. Or Windows XP 🙂

An ASCII version of Star Wars Episode IV


This you need to check out! Open a command prompt, and type:


Note that you need, of course, to have telnet. Found here while looking for windows command prompt shortcuts. The full article is very interesting, so don’t go directly to the end of it. Note 2: it works also on linux, if you have telnet installed. Have fun! 🙂