System uptime is available in chrome without enabling the developer mode via the crosh window and the command top. I'd like to be able to access this programmatically within my chrome app. I'm not seeing it jump out at me in the chrome apis here.
Uptime usually includes both the load average and the time since the last boot-up. I'm mostly interested in the time since the last boot-up.
How can I get system uptime programmatically on the chrome-os platform - without enabling developer mode?
I do not have a chrome development environment set up at the moment, or I'd try. But chrome.system.cpu.getInfo() looks like it will give you what you want. Note that the processors array gives cumulative time (total) that may be equivalent to time since last boot.
See https://developer.chrome.com/apps/system_cpu.
My goal is to write to a file (that the user whenever the user launches an application, such as FireFox) and timestamp the event.
The tricky part is having to do this from the kernel (or a module loaded onto the kernel).
From the research I've done so far (sources listed below), the execve system call seemed the most viable. As it had the filename of the process it was handling which seemed like gold at the time, but I quickly learned that it wasn't as useful as I thought since this system call isn't limited to user-related operations.
So then I thought of using ps -ef as it listed all the current running processes and I would just have to filter through which ones were applications opened by the user.
But the issue with that method is that I would have to poll every X seconds so, it has the potential to miss something if the user launched and closed an application within the time that I didn't call ps -ef.
I've also realized that writing to a file would be a challenge as well, since you don't have access to the standard library from the kernel. So my guess for that would be making use of proc somehow to allow the user to actually access the information that I'm trying to log.
Basically I'm running out of leads and I'd greatly appreciate it if anyone could point me in the right direction.
Thanks.
Sources:
http://tldp.org/LDP/lkmpg/2.6/html/x978.html (not very recent)
https://0xax.gitbooks.io/linux-insides/content/SysCall/syscall-4.html
First, writing to a file or reading a real file from the kernel is a bad idea which is not used in the kernel. There is of course VFS files, like /sys/fs or /proc, but this is a special case and this is allowed.
See this article in Linux Journal,
"Driving Me Nuts - Things You Never Should Do in the Kernel" by Greg Kroach-Hrtman
http://www.linuxjournal.com/article/8110
Every new process that is created in Linux, adds an entry under /proc,
as /proc/pidNum, where pidNum is the Process ID of the new process.
You can find out the name of the new application which was invoked simply by
cat /proc/pidNum/cmdline.
So for example, if your crond daemon has pid 1336, then
$cat /proc/1336/cmdline
will give
cron
And there are ways to monitor adding entries to a folder in Linux.
So I am trying to keep my Node server on a embedded computer running when it is out in the field. This lead me to leveraging inittab's respawn action. Here is the file I added to inittab:
node:5:respawn:node /path/to/node/files &
I know for a fact that when I startup this node application from command line, it does not get to the bottom of the main body and console.log "done" until a good 2-3 seconds after I issue the command.
So I feel like in that 2-3 second window the OS just keeps firing off respawns of the node app. I see in the error logs too in fact that the kernel ends up killing off a bunch of node processes because its running out of memory and stuff... plus I do get the 'node' process respawning too fast will suspend for 5 minutes message too.
I tried wrapping this in a script, dint work. I know I can use crontab but thats every minute... am I doing something wrong? or should I have a different approach all together?
Any and all advice is welcome!
TIA
Surely too late for you, but in case someone else finds such a problem: try removing the & from the command invocation.
What happens is that when the command goes to the background (thanks to the &), the parent (init) sees that it exited, and respawns it. Result: a storm of new instantations of your command.
Worse, you mention embedded, so I guess you are using busybox, whose init won't rate-limit the respawning - as would other implementations. So the respawning will only end when the system is out of memory.
inittab is overkill for this. I found out what I need is a process monitor. I found one that is lightweight and effective; it has some good reports of working great out in the field. http://en.wikipedia.org/wiki/Process_control_daemon
Using this would entail configuring this daemon to start and monitor your Node.js application for you.
That is a solution that works from the OS side.
Another way to do it is as follows. So if you are trying to keep Node.js running like I was, there are several modules written meant to keep other Node.js apps running. To mention a couple there are forever and respawn. I chose to use respawn.
This method entails starting one app written in Node.js that uses the respawn module to start and monitor the actual Node.js app you were interested in keeping running anyway.
Of course the downside of this is that if the Node.js engine (V8) goes down altogether then both your monitoring and monitored process will go down with it :-(. But its better than nothing!
PCD would be the ideal option. It would go down probably only if the OS goes down, and if the OS goes down then hope fully one has a watchdog in place to reboot the device/hardware.
Niko
Every morning when I get into work I launch about a dozen apps and whatnot (FF, TB, VSx2-3, Eclipse, SSH, SVN update x2-3). Needles to say this does a good job of warming up my HDD for the day. I rather suspect that it would run a lot faster if they were launched sequentially (not to mention that I wouldn't need to click in 17 different places).
Is there a preexisting product that can kick off a sequence of tasks/apps/etc. where each task is only started after the last app is done hammering the HDD?
It would nerd to be able to kick apps like VS and firefox and also be able to trigger explorer context menu items like SVN update in TortoiseSVN.
Try SlickRun, it's free, I've used it for years, I use it constantly and I'd be lost without it.
Think of it like a configurable Start->Run command, it'll do what you want (you can configure n second pauses between multiple commands), and if you install it you'll use it for a thousand different things before the first week is out.
P.S. I have no stake in SlickRun, I just like it :)
Unfortunately, I don't know of any software that can do this for you automatically.
However, can't you trigger the updates through a console SVN task? If so, can't this be done by creating a batch file? It's low tech, and you might want to add a few pauses between each task, but it should do what you want.
As you mention TortoiseSVN, I'll assume your O/S is windows.
You could launch an Autohotkey script at startup. I don't think it can easily detect HDD activity, but you can at least wait until each window appears with the WinWaitActive command.
If each application has an average time they take to complete, you could simply use Windows' Scheduled Tasks application. Obviously you'll need to be running Windows but Scheduled Tasks can be found in the Control Panel.
Execute "Add Schedules Task", select the program, the frequency and then the specific time.
As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.
Closed 10 years ago.
Lots of people have things that their systems do for them or for their teams. Source control post-commit hooks are a standard example: have an automated build system that checks out the latest source, compiles, tests, and packages it is a back-office hack that most of us probably use.
What other cool things have you done?
We had one developer in our team who wasn't familiar with the concept of a subversion conflict. He deduced that if he simply deleted all that weird stuff in his code and clicked resolve that everything was ok (i.e. knocking out all the other changes in the file....)
Regardless to say, after the 5th time this occurred, and the 5th time that I had to explain why that defect that I just closed was reoccuring, I wrote a script.
It would diff for the changes to a file to see whether the consecutive checkin deleted all the previous changes and that they were done by the nameless developer.
It would then send an email to the boss with a description of what happened, and how much work was lost during the checkin.
There was no 7th occurrence.
We have a traffic-light that shows whether our daily build succeeds, has failed tests or simply doesn't build.
Also, we have a light bar that lights up for a few seconds whenever we receive an upload from a customer.
We aren't staffed 24x7 but we have critical processes that run throughout the night. We created an in-house alerts system to notify us of serious system issues, failed mission-critical processes, etc. It uses text-to-speech to create a descriptive message and then connects to our automated dialer to call the appropriate people with the message.
Working at a web design company I configured our dev server so we could see a working copy of a project in real time by a sub domain name. So if your name was joe and you were working on project jetfuel you would go to joe.jetfuel.test-example.com and you could see your changes instantly without committing.
This was a simple hack that used sub domain names as a partial directory structure. Our htdocs path looked like this htdocs/tag/project. We had a script (a php app that you would access by setup.test-example.com) that would create a new tag name for you and checkout whatever version you wanted and call the deploy script for that project. If it succeeded it would forward you to the new sub domain. You could then work on this new copy by a samba share.
This worked really well for us since we always deployed to the same linux build and our projects had simple database requirements.
Our original reason for doing this was because our developers worked on all kinds of different platforms. Besides fixing this platform problem this was awesome for viewing changes and testing. We had all kinds of tags ranging from peoples names, trunk versions, test tags, all the way to prototypes like jquery-menu-hack.jetfuel.test-example.com
Now that I look back I wonder how much easier it would have been to run virtual machines.
We had a dev working on a classic ASP site that didn't believe in source control. The code went from his machine straight to the production box. This lead to issues with lost changes or the inability to revert back to a stable version. Since CruiseControl.Net has the ability to monitor a directory, I added a project that actually checked in files whenever they were copied to production. Completely backward from CC.Net's original intent, but we didn't lose any more code.
Put in a pre-commit hook that checks the bug comment refers to an open bug, assigned to the user doing the checkin. (SCMBug can do this).
Then to make life REALLY interesting, spell check the comments!!
The commit comment, and the one in the code. (spell is my buddy)
Run the code through a code formatter set to compayn standard; and diff it to the original: if it's not in company offical format: reject the commit.
Do a coverage test with the unit test build.
Email all mistakes/errors caused to the development team.
I left OUT the name of the developer. They know they did it.
Not exactly hacks, but a couple of must-haves for IT dev work:
If you're using subversion, you've got to use CommitMonitor. (http://tools.tortoisesvn.net/CommitMonitor) It lets you monitor svn repositories for new commits & then review the new commits. Great if you're wanting to stay on top of what your team is doing. Particularly if you have a couple of juniors that need to be watched. ;)
Rsnapshot (http://www.rsnapshot.org/) is also invaluable - we have complete backup snapshots of our entire filesystem every four hours going back 2 years, and every day beyond that. It's like a data cube for your filesystem! The peace of mind this gives is pure bliss. :)
Hardly a hack, but back in the day, on our speedy VAX 11/730, our overnight process would print the file "BLAMMO.TXT" on the printer if something went amiss. Every morning, the first stop was the printer when coming in.
Back in the dotCom days about 9 years ago, I had to hack a failover system between two different locations. We had a funky setup with a powerbuilder front end website, and powerbuilder managment tool. Data was stored in MSSQL 7.0. The webservers used IPX to communicate to the SQL Servers (don't ask). Anyway, I was responsbile for coming up with a failover plan.
I ended up hacking together some linux boxes, and had them run our external DNS. One at each location. We had a remote site w/ webserver, and sql server I got SQL transaction replication working over a 128k ISDN IPX connection (of all things). Then built a monitoring tool at our production site to send packets out to various upstream network handoffs. If we experienced more than 20% outage the primary site, the monitoring tool ran a perl script on the Debian box to change DNS and point to our 2ndary. Our secondary had a heartbeat w/ our primary DNS, and monitoring station. It would duplicate records unless it lost both connections then it would roll over to pointing DNS to backup location.
The primary site would shut down the SQL server at the primary location to break replication. Automated site to site failover using 128k ISDN IPX connection :)
Back at my previous job, we had to audit many tables for data changes (inserts, updates and deletes). Our support crew had to be able to search through this data to find changes that users made.
The temporary solution that had become semi-permanent was to store each non-select query. However this was a large system, that the table would grow by about 1.5GB a day.
The solution I came up with was to create a script that for all tables in an external list, created the appropriate triggers that audit each table, row, column, before and after, when and by whom and store it in our new audit table. This table grew by about 10% the size of the older version and stored much more usable data. It enabled us to create a UI to search and view every change made to our data, without requiring any knowledge of SQL for our support team or business users.
This is at a lesser level, but I am fairly proud of a make file I wrote for compiling code for my research. It only needs to be given your source and header file names that can take care of the rest all by itself (though it does make the one assumption that you will not be compiling any header files into objects, only source files get compiled). The other downsides are the fact that it relies on the GNU make program's second expansion feature, so I don't know if it works on other make programs. Additionally the compiler used needs to support something similar to gcc's -MM feature. Here is hoping that no one laughs at it.
-include prereqs.mk
HEADERS=$(SRC_DIR)/gs_lib.h $(SRC_DIR)/gs_structs.h
SOURCES=$(SRC_DIR)/main.cpp $(SRC_DIR)/gs_lib.cpp
OBJECTS=$(patsubst $(SRC_DIR)/%.cpp,$(OBJ_DIR)/%.o,$(SOURCES))
release: FLAGS=$(GEN_FLAGS)$(OPT_FLAGS)
release: $(OBJECTS) prereqs.mk
$(CXX) $(FLAGS) $(LINKER_FLAGS) $(OUTPUT_FLAG) $(EXECUTABLE) $(OBJECTS)
prereqs.mk: $(SOURCES) $(HEADERS)
$(CXX) $(DIR_FLAGS) $(MAKE_FLAG) $(SOURCES) | sed 's,\([abcdefghijklmnopqrstuvwxyz_]*\).o:,\1= \\\n,' > $#
.SECONDEXPANSION:
$(OBJECTS): $$($$(patsubst $(OBJ_DIR)/%.o,%,$$#))
$(CXX) $(FLAGS) $(NO_LINK_FLAG) $(OUTPUT_FLAG) $# $(patsubst $(OBJ_DIR)/%.o,$(SRC_DIR)/%.cpp,$#)
Obviously I dropped the definition of a number of variables, but I think it gets the idea across.
Since my coding tools and style are compatible with the requirements of this script I like to use it. All I need to do to add (a) new piece(s) of source code is add its name(s) to the appropriate variable and the rest is taken care of.
We have Twitter accounts for many projects which tweet things like commit messages, notices from builds, failed unit tests, deployments, bug tracking activity - any kind of event associated with the project. Running a client like Twitter Gwibber (which displays a pop-up for each new status) is a great way to stay in touch with the activity on the projects you are interested. Using Twitter is good as you can take advantage of all the 3rd party apps - such as the iPhone clients.
Add commit-hook check for VRML/3d-model files with absolute path to textures/images. f:/maya/my-textures/newproject/xxxx.png just doesn't belong on the server.
Back in the 1993, when source control systems were really expensive and unwieldy, the company I worked about had an in-house source control built as 4DOS scripts. It wasn't as sofisticated as most current source control systems, for example it didn't have branching or integrates, but it did the basic job of supporting revisions history, checkout/checkin and rudimentary conflict resolution.