static void worker(void* arg) {
  struct uv__work* w;
  QUEUE* q;

  (void) arg;

  for (;;) {
    uv_mutex_lock(&mutex);

    while (QUEUE_EMPTY(&wq))
      uv_cond_wait(&cond, &mutex);

    q = QUEUE_HEAD(&wq);

    if (q == &exit_message)
      uv_cond_signal(&cond);
    else {
      QUEUE_REMOVE(q);
      QUEUE_INIT(q);  /* Signal uv_cancel() that the work req is
                             executing. */
    }

    uv_mutex_unlock(&mutex);

    if (q == &exit_message)
      break;

    w = QUEUE_DATA(q, struct uv__work, wq);
    w->work(w);

    uv_mutex_lock(&w->loop->wq_mutex);
    w->work = NULL;  /* Signal uv_cancel() that the work req is done
                        executing. */
    QUEUE_INSERT_TAIL(&w->loop->wq, &w->wq);
    uv_async_send(&w->loop->wq_async);
    uv_mutex_unlock(&w->loop->wq_mutex);
  }
}

#include <thread>
#include <functional>
#include <boost/asio.hpp>

int main ( int argc, char* argv[] ) {
    asio::io_service io_service;
    asio::io_service::work work(io_service);

    std::vector<std::thread> threadPool;

    for(size_t t = 0; t < std::thread::hardware_concurrency(); t++){
        threadPool.push_back(thread(std::bind(&asio::io_service::run, &io_service)));
    }

    io_service.post(std::bind(an_expensive_calculation, 42));
    io_service.post(std::bind(a_long_running_task, 123));

    //Do some things with the main thread

    io_service.stop();
    for(std::thread& t : threadPool) {
        t.join();
    }
}

//
// memcached.c
//
typedef struct {
    pthread_t thread_id;        /* unique ID of this thread */
    struct event_base *base;    /* libevent handle this thread uses */
    struct event notify_event;  /* listen event for notify pipe */
    int notify_receive_fd;      /* receiving end of notify pipe */
    int notify_send_fd;         /* sending end of notify pipe */
    struct thread_stats stats;  /* Stats generated by this thread */
    struct conn_queue *new_conn_queue; /* queue of new connections to handle */
    cache_t *suffix_cache;      /* suffix cache */
    uint8_t item_lock_type;     /* use fine-grained or global item lock */
} LIBEVENT_THREAD;

//
// thread.c
//
void thread_init(int nthreads, struct event_base *main_base) {
//
// 中略
//
    threads = calloc(nthreads, sizeof(LIBEVENT_THREAD));
//
// さらに中略
//
    for (i = 0; i < nthreads; i++) {
        int fds[2];
        if (pipe(fds)) {
            perror("Can't create notify pipe");
            exit(1);
        }

        threads[i].notify_receive_fd = fds[0];
        threads[i].notify_send_fd = fds[1];

        setup_thread(&threads[i]);
        /* Reserve three fds for the libevent base, and two for the pipe */
        stats.reserved_fds += 5;
    }

    /* Create threads after we've done all the libevent setup. */
    for (i = 0; i < nthreads; i++) {
        create_worker(worker_libevent, &threads[i]);
    }

    /* Wait for all the threads to set themselves up before returning. */
    pthread_mutex_lock(&init_lock);
    wait_for_thread_registration(nthreads);
    pthread_mutex_unlock(&init_lock);
}

#define lll_futex_wait(futex, val, private) \
  lll_futex_timed_wait(futex, val, NULL, private)

#define lll_futex_timed_wait(futex, val, timeout, private) \
  ({                                         \
    register const struct timespec *__to __asm ("r10") = timeout;          \
    int __status;                                \
    register __typeof (val) _val __asm ("edx") = (val);                \
    __asm __volatile ("syscall"                            \
             : "=a" (__status)                         \
             : "0" (SYS_futex), "D" (futex),                 \
           "S" (__lll_private_flag (FUTEX_WAIT, private)),         \
           "d" (_val), "r" (__to)                    \
             : "memory", "cc", "r11", "cx");                 \
    __status;                                    \
  })

futex(futex, FUTEX_WAIT, val, timeout, NULL, 0);  // 便宜上、上記コードの引数の変数名をそのままつかっているが、
                                                  // 1つめのfutexはシステムコールのfutexで、
                                                  // 2つめは引数のpthread_cond_tの__futexメンバ変数のアドレス

LOCKFILE=/tmp/my.lockfile

(
    flock -n 200 || exit 1

    # do something
) 200>$LOCKFILE

└── project
    ├── src
    │   ├── libmy.a
    │   ├── libmy.so -> libmy.so.1
    │   ├── libmy.so.1
    │   ├── Makefile
    │   ├── mylib.c
    │   ├── mylib.h
    │   └── mylib.o
    └── t
        ├── Makefile
        ├── mytest
        ├── mytest.c
        └── mytest.o

$ cc -I../src -L../src -Wl,-rpath=../src *.c -lmy -o mytest
$ readelf -d mytest
Dynamic section at offset 0xe30 contains 22 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [libmy.so.1]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x000000000000000f (RPATH)              Library rpath: [../src]
 0x000000000000000c (INIT)               0x4004c8
 0x000000000000000d (FINI)               0x4006f8
 0x000000006ffffef5 (GNU_HASH)           0x400298
 0x0000000000000005 (STRTAB)             0x4003c0
 0x0000000000000006 (SYMTAB)             0x4002d0
 0x000000000000000a (STRSZ)              134 (bytes)
 0x000000000000000b (SYMENT)             24 (bytes)
 0x0000000000000015 (DEBUG)              0x0
 0x0000000000000003 (PLTGOT)             0x600fe8
 0x0000000000000002 (PLTRELSZ)           48 (bytes)
 0x0000000000000014 (PLTREL)             RELA
 0x0000000000000017 (JMPREL)             0x400498
 0x0000000000000007 (RELA)               0x400480
 0x0000000000000008 (RELASZ)             24 (bytes)
 0x0000000000000009 (RELAENT)            24 (bytes)
 0x000000006ffffffe (VERNEED)            0x400460
 0x000000006fffffff (VERNEEDNUM)         1
 0x000000006ffffff0 (VERSYM)             0x400446
 0x0000000000000000 (NULL)               0x0

dyld: Library not loaded: libmy.1.dylib
  Referenced from: /Users/path/to/project/t/./mytest
  Reason: image not found
zsh: trace trap  ./mytest

-- 中略
Load command 11
          cmd LC_LOAD_DYLIB
      cmdsize 40
         name libmy.1.dylib (offset 24)
   time stamp 2 Thu Jan  1 09:00:02 1970
      current version 1.0.0
compatibility version 0.0.0

echo "echo おやつの時間です > $TTY"| at teatime
echo "echo はろー > $TTY" | at now + 3 minute

mtr mojavy.com

gem list | column
mount | column -t
grep -v '^#' /etc/apt/sources.list | column -t

sshfs name@server:/path/to/dir /path/to/mount/point
fusermount -u /path/to/mount/point  # unmount

$ dig +short txt banana.wp.dg.cx
"Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. It is one of the oldest cultivated plants. They are native to tropical South and Southeast Asia, and are likely to have been first domesticated in Papua New " "Guinea. Today, they are cultivated throughout the tropics. They are grown in at least 107 countries, primarily for their... http://en.wikipedia.org/wiki/Banana"