| #!/bin/bash | |
| # | |
| # usdt - trace user statically defined tracepoints. User-level dynamic tracing. | |
| # Written using Linux ftrace. Experimental. | |
| # | |
| # WARNING: This is a proof of concept for USDT tracing from Linux ftrace, and | |
| # is not safe to use in production environments. In particular, the -i option | |
| # sets memory semaphores by piping the output of printf through dd and then | |
| # to process memory via /proc/PID/mem. Yes, this program pipes the output of | |
| # the shell directly over top of live process memory. If you don't understand |
Services declared as oneshot are expected to take some action and exit immediatelly (thus, they are not really services,
no running processes remain). A common pattern for these type of service is to be defined by a setup and a teardown action.
Let's create a example foo service that when started creates a file, and when stopped it deletes it.
Create executable file /opt/foo/setup-foo.sh:
| #!/bin/sh | |
| # also see http://marc.merlins.org/perso/btrfs/post_2014-03-19_Btrfs-Tips_-Btrfs-Scrub-and-Btrfs-Filesystem-Repair.html | |
| for fs in $(grep ' btrfs ' /proc/mounts | cut -d' ' -f1 | sort -u) | |
| do | |
| starttime="$(date "+%Y-%m-%d %H:%M:%S")" | |
| logger "Starting btrfs scrub on $fs" | |
| btrfs scrub start -Bd "$fs" | |
| journalctl -q -k --since "$starttime" | grep BTRFS |
| // http://stackoverflow.com/a/107657 | |
| constexpr unsigned long long int HashStringToInt(const char *str, unsigned long long int hash = 0) | |
| { | |
| return (*str == 0) ? hash : 101 * HashStringToInt(str + 1) + *str; | |
| } | |
| void simple_switch(const std::string &str) | |
| { | |
| switch (HashStringToInt(str.c_str())) | |
| { |
| xsd-4.0.0+dep/xsd/examples/cxx/parser/hello$ xsd cxx-tree hello.xsd | |
| xsd-4.0.0+dep/xsd/examples/cxx/parser/hello$ ls | |
| driver.cxx hello.cxx hello.hxx hello.xml hello.xsd makefile README | |
| xsd-4.0.0+dep/xsd/examples/cxx/parser/hello$ cat hello.hxx | |
| // Copyright (c) 2005-2014 Code Synthesis Tools CC | |
| // | |
| // This program was generated by CodeSynthesis XSD, an XML Schema to | |
| // C++ data binding compiler. |
| /* | |
| * Here's a sample kernel module showing the use of jprobes to dump | |
| * the arguments of third-party network driver for Bercut ETN. | |
| * | |
| * For more information on theory of operation of jprobes, see | |
| * Documentation/kprobes.txt | |
| * | |
| * Build and insert the kernel module as done in the kprobe example. | |
| * You will see the trace data in /var/log/messages and on the | |
| * console whenever do_fork() is invoked to create a new process. |
| # fshow - git commit browser (enter for show, ctrl-d for diff, ` toggles sort) | |
| fshow() { | |
| local out shas sha q k | |
| while out=$( | |
| git log --graph --color=always \ | |
| --format="%C(auto)%h%d %s %C(black)%C(bold)%cr" "$@" | | |
| fzf --ansi --multi --no-sort --reverse --query="$q" \ | |
| --print-query --expect=ctrl-d --toggle-sort=\`); do | |
| q=$(head -1 <<< "$out") | |
| k=$(head -2 <<< "$out" | tail -1) |
| What exactly is "iowait"? | |
| To summarize it in one sentence, 'iowait' is the percentage | |
| of time the CPU is idle AND there is at least one I/O | |
| in progress. | |
| Each CPU can be in one of four states: user, sys, idle, iowait. | |
| Performance tools such as vmstat, iostat, sar, etc. print | |
| out these four states as a percentage. The sar tool can | |
| print out the states on a per CPU basis (-P flag) but most |
| # File Transfer model #3 | |
| # | |
| # In which the client requests each chunk individually, using | |
| # command pipelining to give us a credit-based flow control. | |
| import os | |
| import sys | |
| from threading import Thread | |
| import zmq |
