Disclaimer: These questions and answers aren't at all mine. These were scavanged around in the web. I hope it helps.
Answer: Linux is the most commonly used operating system that is open source and free. For any computer, the operating system acts as the backbone, and it is most important software that is required for any computer.
| # Scan IP range | |
| LOS_24_IP="ENTER_IP_TO_SCAN";IP=$(echo $LOS_24_IP | cut -d"." -f1,2,3);for i in $(seq 1 255); do NEW_IP=$(echo $IP.$i); (timeout .1 openssl s_client $NEW_IP 2>&1 | grep -q "connect:errno" && echo "$NEW_IP,up" 2>/dev/null) 2>/dev/null ;done |
| package main | |
| import ( | |
| "fmt" | |
| "github.com/danrl/golibby/queue" | |
| "github.com/danrl/golibby/stack" | |
| "github.com/danrl/golibby/graph" | |
| ) |
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
Tcpdump is a commandline tool that is used to dump traffic on a network. This tool comes in hand when you want to analyse network captures within the command line. Basically it can do most of the wireshark job.
NOTE This guide might not be complete it just serve as a reference to me.
This is a collection of books that I've researched, scanned the TOCs of, and am currently working through. The books are selected based on quality of content, reviews, and reccommendations of various 'best of' lists.
The goal of this collection is to promote mastery of generally applicable programming concepts.
Most topics are covered with Python as the primary language due to its conciseness, which is ideal for learning & practicing new concepts with minimal syntactic boilerplate.
JavaScript & Kotlin are listed in the Tooling section; as they allow extension of VS Code and the IntelliJ suite of IDEs, which cover most development needs.
• 45-minute systems interview, focus on responding to real world problems with an unhealthy service, such as a web server or database. The interview will start off at a high level troubleshooting a likely scenario, dig deeper to find the cause and some possible solutions for it. The goal is to probe your knowledge of systems at scale and under load, so keep in mind the challenges of the Facebook environment.
• Focus on things such as tooling, memory management and unix process lifecycle.
More specifically, linux troubleshooting and debugging. Understanding things like memory, io, cpu, shell, memory etc. would be pretty helpful. Knowing how to actually write a unix shell would also be a good idea. What tools might you use to debug something? On another note, this interview will likely push your boundaries of what you know (and how to implement it).
Interview is all about taking an ambiguous question of how you might build a system and letting
L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns
Compress 1K bytes with Zippy ............. 3,000 ns = 3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs
SSD random read ........................ 150,000 ns = 150 µs
Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs
| #!/usr/bin/python | |
| # All SSH libraries for Python are junk (2011-10-13). | |
| # Too low-level (libssh2), too buggy (paramiko), too complicated | |
| # (both), too poor in features (no use of the agent, for instance) | |
| # Here is the right solution today: | |
| import subprocess | |
| import sys |