why i like netstat (h/t @icco) pic.twitter.com/PunGzBqjLg
— Julia Evans (@b0rk) July 19, 2016
Showing posts with label linux. Show all posts
Showing posts with label linux. Show all posts
Tuesday, 19 July 2016
Monday, 18 July 2016
some words about perf (this one's gonna need more than one page) pic.twitter.com/F4eqpCaaWe
— Julia Evans (@b0rk) July 18, 2016
Sunday, 19 June 2016
joejag/dotfiles: Every dev should have some dotfiles, these are mine
joejag/dotfiles: Every dev should have some dotfiles, these are mine: "Every dev should have some dotfiles, these are mine"
'via Blog this'
'via Blog this'
Linux directory structure chart
Oh my god whoever made thing thank you! pic.twitter.com/XalO15FOPn— 49thSecurityDivision (@49SD) June 18, 2016
Monday, 16 May 2016
CompleteNewbiesClickHere - Linux Kernel Newbies
CompleteNewbiesClickHere - Linux Kernel Newbies: "First advice I got when I entered #kernelnewbies a year ago, was to download kernel version 0.0.1. It's a good start for someone who doesn't know jack about kernels, and wants to see a very basic one. [Dan Aloni]
[Sherilyn] The 0.01 kernel downloads to about 10000 lines of C and assembler, which is fairly manageable. Note that it's a barely functional UNIX with tons of bugs, but that doesn't stop it being useful if (like me) you just want to get a quick snapshot of the way in which a UNIX system boots up and starts executing processes, and a broad, uncluttered picture of the kernel system call API. I have written the following Wiki pages which may be of use as an introduction to kernel programming. Please add any corrections, etc."
'via Blog this'
[Sherilyn] The 0.01 kernel downloads to about 10000 lines of C and assembler, which is fairly manageable. Note that it's a barely functional UNIX with tons of bugs, but that doesn't stop it being useful if (like me) you just want to get a quick snapshot of the way in which a UNIX system boots up and starts executing processes, and a broad, uncluttered picture of the kernel system call API. I have written the following Wiki pages which may be of use as an introduction to kernel programming. Please add any corrections, etc."
'via Blog this'
Monday, 25 April 2016
Dan Luu: Recommended Programming blogs
Programming blogs: "Programming blogs
This is one of those “N technical things every programmer must read” lists, except that “programmer” is way too broad a term and the styles of writing people find helpful for them are too different for any such list to contain a non-zero number of items (if you want the entire list to be helpful to everyone). So here’s a list of some things you might want to read, and why you might (or might not) want to read them."
'via Blog this'
This is one of those “N technical things every programmer must read” lists, except that “programmer” is way too broad a term and the styles of writing people find helpful for them are too different for any such list to contain a non-zero number of items (if you want the entire list to be helpful to everyone). So here’s a list of some things you might want to read, and why you might (or might not) want to read them."
'via Blog this'
Tuesday, 12 April 2016
Dan Luu: Notes on Google's Site Reliability Engineering book
Notes on Google's Site Reliability Engineering book: "Notes on Google's Site Reliability Engineering book"
'via Blog this'
'via Blog this'
Monday, 11 April 2016
Brendan Gregg: SREcon 2016 Performance Checklists for SREs
SREcon 2016 Performance Checklists for SREs:
hap://techblog.neSlix.com/2015/11/linux-‐performance-‐analysis-‐in-‐60s.html
hap://techblog.neSlix.com/2015/11/linux-‐performance-‐analysis-‐in-‐60s.html
Saturday, 2 April 2016
bcc: Dynamic Tracing Tools for Linux (IOvisor github)
bcc: "bcc is more than just tools. The BPF enhancements that bcc uses were originally intended for software defined networking (SDN). In bcc, there are examples of this with distributed bridges, HTTP filters, fast packet droppers, and tunnel monitors. BPF was enhanced to support more than just networking, and has general tracing support in the Linux 4.x series. bcc is really a compiler for BPF, that comes with many sample tools. So far bcc has both Python and lua front ends. bcc/BPF, or just BPF, should become an standard resource for performance monitoring and analysis tools, to provide detailed metrics beyond /proc. Latency heat maps, flame graphs, and more should become commonplace in performance GUIs, powered by BPF."
'via Blog this'
'via Blog this'
Thursday, 31 March 2016
Linux IOVisor versus Data Plane Development Kit
Data Plane Development Kit - Wikipedia, the free encyclopedia: "The Data Plane Development Kit (DPDK) is a set of data plane libraries and network interface controller drivers for fast packet processing. The DPDK provides a programming framework for Intel x86 processors and enables faster development of high speed data packet networking applications.[1][2] It scales from Intel Atom processors to Intel Xeon processors and support for other processor architectures like IBM POWER8 are under progress.[3] It is provided and supported under the open source[4] BSD license."
http://www.linuxfoundation.org/news-media/announcements/2015/08/test
“IO Visor will work closely with the Linux kernel community to advance universal IO extensibility for Linux. This collaboration is critically important as virtualization is putting more demands on flexibility, performance and security,” said Jim Zemlin, executive director, The Linux Foundation. “Open source software and collaborative development are the ingredients for addressing massive change in any industry. IO Visor will provide the essential framework for this work on Linux virtualization and networking.”
"Advancing IO and network virtualization in the Linux stack can be an enabler of agility and elasticity, which are key requirements for cloud deployments and applications. IO Visor Project’s mission to bring universal IO extensibility to the Linux kernel will accelerate innovation of virtual network functions in SDN and NFV deployments,” said Rohit Mehra, Vice President of Network Infrastructure, IDC. “The ability to create, load and unload in-kernel functions will enable developers in many upstream and downstream open source projects. What’s more, as an initiative under the auspices of the Linux Foundation, the IO Visor Project has the potential for credibility and momentum to benefit the diverse community of vendors and service providers, and ultimately enterprise IT.”
Probing the JVM with BPF/BCC | All Your Base Are Belong To Us
Probing the JVM with BPF/BCC | All Your Base Are Belong To Us: "Probing the JVM with BPF/BCC
Now that BCC has support for USDT probes, another thing I wanted to try is look at OpenJDK probes and extract some useful examples. To follow along, install a recent OpenJDK (I used 1.8) that has USDT probes enabled.
On my Fedora 22, sudo dnf install java was just enough for everything. Conveniently, OpenJDK ships with a set of .stp files that contain probe definitions. Here’s an example — and there are many more in your $JAVA_HOME/tapset directory:"
'via Blog this'
Now that BCC has support for USDT probes, another thing I wanted to try is look at OpenJDK probes and extract some useful examples. To follow along, install a recent OpenJDK (I used 1.8) that has USDT probes enabled.
On my Fedora 22, sudo dnf install java was just enough for everything. Conveniently, OpenJDK ships with a set of .stp files that contain probe definitions. Here’s an example — and there are many more in your $JAVA_HOME/tapset directory:"
'via Blog this'
Monday, 28 March 2016
You can be a kernel hacker! - Julia Evans
You can be a kernel hacker! - Julia Evans: "
When I started Hacker School, I wanted to learn how the Linux kernel works. I'd been using Linux for ten years, but I still didn't understand very well what my kernel did. While there, I found out that: the Linux kernel source code isn't all totally impossible to understand kernel programming is not just for wizards, it can also be for me! systems programming is REALLY INTERESTING I could write toy kernel modules, for fun! and, most surprisingly of all, all of this stuff was useful. I hadn't been doing low level programming at all -- I'd written a little bit of C in university, and otherwise had been doing web development and machine learning. But it turned out that my newfound operating systems knowledge helped me solve regular programming tasks more easily. I also now feel like if I were to be put on Survivor: fix a bug in my kernel's USB driver, I'd stand a chance of not being immediately kicked off the island. This is all going to be about Linux, but a lot of the same concepts apply to OS X. We'll talk about
When I started Hacker School, I wanted to learn how the Linux kernel works. I'd been using Linux for ten years, but I still didn't understand very well what my kernel did. While there, I found out that: the Linux kernel source code isn't all totally impossible to understand kernel programming is not just for wizards, it can also be for me! systems programming is REALLY INTERESTING I could write toy kernel modules, for fun! and, most surprisingly of all, all of this stuff was useful. I hadn't been doing low level programming at all -- I'd written a little bit of C in university, and otherwise had been doing web development and machine learning. But it turned out that my newfound operating systems knowledge helped me solve regular programming tasks more easily. I also now feel like if I were to be put on Survivor: fix a bug in my kernel's USB driver, I'd stand a chance of not being immediately kicked off the island. This is all going to be about Linux, but a lot of the same concepts apply to OS X. We'll talk about
- what even is a kernel?
- why bother learning about this stuff?
- A few strategies for understanding the Linux kernel better, on your own terms:
- strace all the things!
- Read some kernel code!
- Write a fun kernel module!
- Write an operating system!
- Try the Eudyptula challenge"
Brendan D. Gregg: Linux perf Examples
Linux perf Examples:
"These are some examples of using the perf Linux profiler, which has also been called Performance Counters for Linux (PCL), Linux perf events (LPE), or perf_events. Like Vince Weaver, I'll call it perf_events so that you can search on that term later. Searching for just "perf" finds sites on the police, petroleum, weed control, and a T-shirt. This is not an official perf page, for either perf_events or the T-shirt."
Julia Evans: How does perf work? (in which we read the Linux kernel source)
"These are some examples of using the perf Linux profiler, which has also been called Performance Counters for Linux (PCL), Linux perf events (LPE), or perf_events. Like Vince Weaver, I'll call it perf_events so that you can search on that term later. Searching for just "perf" finds sites on the police, petroleum, weed control, and a T-shirt. This is not an official perf page, for either perf_events or the T-shirt."
Julia Evans: How does perf work? (in which we read the Linux kernel source)
Sunday, 27 March 2016
GitHub - 0xAX/linux-insides: A little bit about a linux kernel
GitHub - 0xAX/linux-insides: A little bit about a linux kernel:
linux-insides
A series of posts about the linux kernel and its insides.
The goal is simple - to share my modest knowledge about the insides of the linux kernel and help people who are interested in linux kernel insides, and other low-level subject matter.
linux-insides
A series of posts about the linux kernel and its insides.
The goal is simple - to share my modest knowledge about the insides of the linux kernel and help people who are interested in linux kernel insides, and other low-level subject matter.
Friday, 18 March 2016
tcpdump is amazing - Julia Evans
tcpdump is amazing - Julia Evans:
Let's suppose you have some slow HTTP requests happening on your machine, and you want to get a distribution of how slow they are. You could add some monitoring somewhere inside your program. Or! You could use tcpdump. Here's how that works!
The secret here is that we can use tcpdump to record network traffic, and then use a tool that we're less scared of (Wireshark) to analyze it on our laptop after.
Let's suppose you have some slow HTTP requests happening on your machine, and you want to get a distribution of how slow they are. You could add some monitoring somewhere inside your program. Or! You could use tcpdump. Here's how that works!
- Use tcpdump to record network traffic on the machine for 10 minutes
- analyze the recording with Wireshark
- be a wizard
The secret here is that we can use tcpdump to record network traffic, and then use a tool that we're less scared of (Wireshark) to analyze it on our laptop after.
Wednesday, 24 February 2016
Why the Linux Mint hack is an indicator of a larger problem - TechRepublic
Why the Linux Mint hack is an indicator of a larger problem - TechRepublic:
While these attacks are regrettable, and part of an infrastructure problem rather than a problem with the distribution itself, it increasingly appears that the Linux Mint team, led by project leader Clement Lefebvre, is spread too thin when it comes to security.
The architectural design of Linux Mint inherits a great deal from its upstream sources Debian and Ubuntu (which is itself based upon Debian). Unfortunately, it lacks any sort of security advisories—Linux Mint evangelists insist that referring to the Ubuntu or Debian advisories is sufficient. Not every package in Linux Mint is available in Ubuntu or Debian, and this argument is further complicated by the fact that updates that work perfectly in Ubuntu or Debian are blacklisted by the Linux Mint team due to compatibility issues.
Linux Mint has the somewhat peculiar design decision of not updating the kernel using the graphical update manager. Users must run apt-get dist-upgrade in a terminal in order to receive updates, when users of Ubuntu receive the same kernel updates automatically. This leaves users vulnerable to potential root exploits and hardware issues. Additionally, there is an issue with shifting release cadences—with version 17, the underlying base moved from standard releases to Long-Term Support (LTS) releases of Ubuntu. Consequently, the packages incorporated are older, on average, than in previous releases, and if blacklisted are both old and insecure.
Wednesday, 27 May 2015
UNIX/LINUX command links
jlevy/the-art-of-command-line
- Meta
- Basics
- Everyday use
- Processing files and data
- System debugging
- One-liners
- Obscure but useful
- MacOS X only
- More resources
- Disclaimer
Stitch Fix ❤ UNIX
Below, we've listed a few problems and their awesome command line solutions. If you know of a more efficient solution, please share in the comments. Otherwise, we'd love to hear how you or your team solve problems with UNIX and the command line.
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