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hdparm -I /dev/sda

/dev/sda:

ATA device, with non-removable media
        Model Number:       Netac SSD  240G
        Serial Number:      5002B725438XXXX
        Firmware Revision:  O1217A
        Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
Standards:
        Supported: 9 8 7 6 5
        Likely used: 9
Configuration:
        Logical         max     current
        cylinders       16383   16383
        heads           16      16
        sectors/track   63      63
        --
        CHS current addressable sectors:   16514064
        LBA    user addressable sectors:  268435455
        LBA48  user addressable sectors:  468862128
        Logical  Sector size:                   512 bytes
        Physical Sector size:                   512 bytes
        Logical Sector-0 offset:                  0 bytes
        device size with M = 1024*1024:      228936 MBytes
        device size with M = 1000*1000:      240057 MBytes (240 GB)
        cache/buffer size  = unknown
        Nominal Media Rotation Rate: Solid State Device
Capabilities:
        LBA, IORDY(can be disabled)
        Queue depth: 32
        Standby timer values: spec'd by Standard, no device specific minimum
        R/W multiple sector transfer: Max = 2   Current = 2
        DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6
             Cycle time: min=120ns recommended=120ns
        PIO: pio0 pio1 pio2 pio3 pio4
             Cycle time: no flow control=120ns  IORDY flow control=120ns
Commands/features:
        Enabled Supported:
           *    SMART feature set
                Security Mode feature set
           *    Power Management feature set
           *    Write cache
           *    Look-ahead
           *    Host Protected Area feature set
           *    WRITE_BUFFER command
           *    READ_BUFFER command
           *    NOP cmd
           *    DOWNLOAD_MICROCODE
                SET_MAX security extension
           *    48-bit Address feature set
           *    Device Configuration Overlay feature set
           *    Mandatory FLUSH_CACHE
           *    FLUSH_CACHE_EXT
           *    SMART error logging
           *    SMART self-test
           *    General Purpose Logging feature set
           *    WRITE_{DMA|MULTIPLE}_FUA_EXT
           *    {READ,WRITE}_DMA_EXT_GPL commands
           *    Segmented DOWNLOAD_MICROCODE
           *    Gen1 signaling speed (1.5Gb/s)
           *    Gen2 signaling speed (3.0Gb/s)
           *    Gen3 signaling speed (6.0Gb/s)
           *    Native Command Queueing (NCQ)
           *    Host-initiated interface power management
           *    Phy event counters
           *    READ_LOG_DMA_EXT equivalent to READ_LOG_EXT
           *    DMA Setup Auto-Activate optimization
                Device-initiated interface power management
           *    Software settings preservation
                Device Sleep (DEVSLP)
           *    SMART Command Transport (SCT) feature set
           *    SCT Write Same (AC2)
           *    SCT Features Control (AC4)
           *    SCT Data Tables (AC5)
           *    DOWNLOAD MICROCODE DMA command
           *    WRITE BUFFER DMA command
           *    READ BUFFER DMA command
           *    Data Set Management TRIM supported (limit 8 blocks)
           *    Deterministic read ZEROs after TRIM
Security:
        Master password revision code = 65534
                supported
        not     enabled
        not     locked
                frozen
        not     expired: security count
                supported: enhanced erase
        2min for SECURITY ERASE UNIT. 2min for ENHANCED SECURITY ERASE UNIT.
Device Sleep:
        DEVSLP Exit Timeout (DETO): 40 ms (drive)
        Minimum DEVSLP Assertion Time (MDAT): 31 ms (drive)
Checksum: correct

hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   25572 MB in  2.00 seconds = 12798.56 MB/sec
 Timing buffered disk reads: 800 MB in  3.01 seconds = 266.08 MB/sec

fdisk -l

Disk /dev/loop0: 81.7 MiB, 85692416 bytes, 167368 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop1: 81.7 MiB, 85639168 bytes, 167264 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop2: 81.6 MiB, 85549056 bytes, 167088 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x5ad18deb

Device     Boot Start       End   Sectors   Size Id Type
/dev/sda1          63 468862127 468862065 223.6G 83 Linux


Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x29049925

Device     Boot      Start        End    Sectors   Size Id Type
/dev/sdb1  *            63  629153594  629153532   300G  7 HPFS/NTFS/exFAT
/dev/sdb2        629153656 1953523711 1324370056 631.5G  f W95 Ext'd (LBA)
/dev/sdb5        629153658 1153466999  524313342   250G  7 HPFS/NTFS/exFAT
/dev/sdb6       1153467063 1782588464  629121402   300G  7 HPFS/NTFS/exFAT
/dev/sdb7       1782589440 1798213631   15624192   7.5G 82 Linux swap / Solaris
/dev/sdb8       1798215680 1953523711  155308032  74.1G 83 Linux

Partition 1 does not start on physical sector boundary.
Partition 5 does not start on physical sector boundary.
Partition 6 does not start on physical sector boundary.


Disk /dev/sdc: 119.2 GiB, 128035676160 bytes, 250069680 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x326f11b9

Device     Boot     Start       End   Sectors   Size Id Type
/dev/sdc1  *           63 248346992 248346930 118.4G  7 HPFS/NTFS/exFAT
/dev/sdc2       248348672 250066943   1718272   839M 27 Hidden NTFS WinRE

/dev/null 伪设备，回收站。写该文件不会产生 IO
/dev/zero 伪设备，会产生空字符流，对它不会产生 IO

dd if=/dev/zero of=/tmp/test bs=1G count=1 oflag=dsync

sync; dd if=/dev/zero of=tempfile bs=1M count=1024; sync

dd if=tempfile of=/dev/null bs=1M count=1024

sudo apt install ncdu

   22.2 GiB [#####     ] /Documents
   16.2 GiB [###       ] /.local
.  13.7 GiB [###       ] /.cache
   10.9 GiB [##        ] /.m2
   10.8 GiB [##        ] /Dropbox
    9.8 GiB [##        ] /Git
    3.2 GiB [          ] /.IntelliJIdea2016.3
    2.2 GiB [          ] /.pyenv
    1.4 GiB [          ] /.IdeaIC2016.3
    1.3 GiB [          ] /.wiznote

┌───ncdu help─────────────────1:Keys───2:Format───3:About──┐
│                                                          │
│       up, k  Move cursor up                              │
│     down, j  Move cursor down                            │
│ right/enter  Open selected directory                     │
│  left, <, h  Open parent directory                       │
│           n  Sort by name (ascending/descending)         │
│           s  Sort by size (ascending/descending)         │
│           C  Sort by items (ascending/descending)        │
│           d  Delete selected file or directory           │
│           t  Toggle dirs before files when sorting       │
│           g  Show percentage and/or graph                │
│                        -- more --                        │
│                                         Press q to close │
└──────────────────────────────────────────────────────────┘

sudo parted /dev/sdb print

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

apt-get update
apt-get upgrade

ssh -p <the port you set> name@server.ip

adduser [nickname_you_want]
adduser [nickname_you_want] sudo        # 或者 visudo

PasswordAuthentication no

sudo /etc/init.d/ssh restart

MaxAuthTries 6

# 禁止 ping
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
# 允许 ping
echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all

*               hard    maxlogins       2

sudo apt install fail2ban

[DEFAULT]
# "ignoreip" can be an IP address, a CIDR mask or a DNS host. Fail2ban will not
# ban a host which matches an address in this list. Several addresses can be
# defined using space separator.
ignoreip = 127.0.0.1/8 123.45.67.89

# "bantime" is the number of seconds that a host is banned.
bantime  = 31536000            ; 1 year

# A host is banned if it has generated "maxretry" during the last "findtime"
# seconds.
findtime = 600
maxretry = 3

w

last

docker run \
    --volume=/:/rootfs:ro \
    --volume=/var/run:/var/run:rw \
    --volume=/sys:/sys:ro \
    --volume=/var/lib/docker/:/var/lib/docker:ro \
    --publish=8080:8080 \
    --detach=true \
    --name=cadvisor \
    google/cadvisor:latest

--privileged=true

--volume=/cgroup:/cgroup:ro 

wget https://github.com/google/cadvisor/releases/download/v0.26.1/cadvisor
chmod 755 cadvisor
./cadvisor

class Person {

	String name;
	int age;

	Person(String name, int age) {
		this.name = name;
		this.age = age;
	}

	@Override
	public String toString() {
		return name;
	}
}

@Test
public void testCollectAdvance() {
	List<Person> persons =
		Arrays.asList(
			new Person("Max", 18),
			new Person("Peter", 23),
			new Person("Pamela", 23),
			new Person("David", 12));

	Supplier<Stream<Person>> supplier = () -> persons.stream();

	Set<Person> nameWithP = supplier.get()
		.filter(p -> p.name.startsWith("P"))
		.collect(Collectors.toSet());
	System.out.println(nameWithP);  // [Pamela, Peter]

	Map<Integer, List<Person>> groupByAge = supplier.get()
		.collect(Collectors.groupingBy(p -> p.age));
	System.out.println(groupByAge);

	Double averageAge = supplier.get()
		.collect(Collectors.averagingInt(p -> p.age));
	System.out.println(averageAge);

	IntSummaryStatistics ageSummary = supplier.get()
		.collect(Collectors.summarizingInt(p -> p.age));
	System.out.println(ageSummary);

	String phrase = supplier.get()
		.filter(p -> p.age >= 18)
		.map(p -> p.name)
		.collect(Collectors.joining(" and ", "In Germany ", " are of legal age."));
	System.out.println(phrase);

	Map<Integer, String> map = supplier.get()
		.collect(Collectors.toMap(
			p -> p.age,
			p -> p.name,
			(name1, name2) -> name1 + ";" + name2
		));
	System.out.println(map);

	// 如果要实现自己的 collector
	Collector<Person, StringJoiner, String> personStringJoinerStringCollector = Collector.of(
		() -> new StringJoiner(" | ", "[ ", " ]"),          // supplier
		(j, p) -> j.add(p.name.toUpperCase()),  // accumulator
		(j1, j2) -> j1.merge(j2),               // combiner
		StringJoiner::toString                  // finisher
	);
	String personStr = supplier.get().collect(personStringJoinerStringCollector);
	System.out.println(personStr);
}

() -> new StringJoiner(" | ")

(joiner, person) -> joiner.add(person.name.toUpperCase())

(j1, j2) -> j1.merge(j2)

class Foo {

	String name;
	List<Bar> bars = new ArrayList<>();

	Foo(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return "Foo{" +
			"name='" + name + '\'' +
			", bars=" + bars +
			'}';
	}
}

class Bar {

	String name;

	Bar(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return "Bar{" +
			"name='" + name + '\'' +
			'}';
	}
}

@Test
public void testFlatMapAdvanced() {
	List<Foo> foos = Lists.newArrayList();

	IntStream.range(1, 4).forEach(i -> foos.add(new Foo("Foo" + i)));
	foos.forEach(f -> IntStream.range(1, 4)
		.forEach(i -> f.bars.add(new Bar("Bar" + i + " <- " + f.name))));

	Supplier<Stream<Foo>> supplier = foos::stream;
	supplier.get()
		.flatMap(f -> f.bars.stream())
		.forEach(b -> System.out.println(b.name));

	List<Bar> list = supplier.get()
		.flatMap(f -> f.bars.stream())
		.collect(Collectors.toList());
	System.out.println(list);
}

reduce(BinaryOperator<T>)
reduce(T, BinaryOperator<T>)
reduce(U, BiFunction<U, ? super T, U>, BinaryOperator<U>)

List<Person> persons =
    Arrays.asList(
        new Person("Max", 18),
        new Person("Peter", 23),
        new Person("Pamela", 23),
        new Person("David", 12));

Supplier<Stream<Person>> supplier = persons::stream;
supplier.get().reduce((p1, p2) -> p1.age > p2.age ? p1 : p2)
    .ifPresent(System.out::println);

	Person finalPerson = supplier.get()
    .reduce(new Person("", 0), (p1, p2) -> {
        p1.age += p2.age;
        p1.name = p1.name.concat(p2.name);
        return p1;
    });
System.out.println(finalPerson);

Integer totalAge = supplier.get()
    .reduce(
        0,
        (sum, p) -> {
            System.out.format("accumulator: sum=%s; person=%s\n", sum, p);
            return sum += p.age;
        },
        (sum1, sum2) -> {
            System.out.format("combiner: sum1=%s; sum2=%s", sum1, sum2);
            return sum1 + sum2;
        }
    );
System.out.println(totalAge);

accumulator: sum=0; person=Person{name='Max', age=18}
accumulator: sum=18; person=Person{name='Peter', age=23}
accumulator: sum=41; person=Person{name='Pamela', age=23}
accumulator: sum=64; person=Person{name='David', age=12}
76

Integer ageSum = persons
    .parallelStream()
    .reduce(0,
        (sum, p) -> {
            System.out.format("accumulator: sum=%s; person=%s\n", sum, p);
            return sum += p.age;
        },
        (sum1, sum2) -> {
            System.out.format("combiner: sum1=%s; sum2=%s\n", sum1, sum2);
            return sum1 + sum2;
        });

// accumulator: sum=0; person=Pamela
// accumulator: sum=0; person=David
// accumulator: sum=0; person=Max
// accumulator: sum=0; person=Peter
// combiner: sum1=18; sum2=23
// combiner: sum1=23; sum2=12
// combiner: sum1=41; sum2=35

    docker save -o /path/to/image.tar image-name:1.0.0
    docker load -i /path/to/image.tar

docker volume create my-vol          # 创建数据卷
docker volume ls                     # 查看所有数据卷
docker volume inspect my-vol         # 查看指定数据卷内容
docker run -d -P \
    --name web \
    # -v my-vol:/wepapp \
    --mount source=my-vol,target=/webapp \
    training/webapp \
    python app.py                   # 启动并挂载一个数据卷 使用 `--mount`
docker inspect web                  # 查看容器中 mount 信息
docker volume rm my-vol             # 移除数据卷

docker volume prune

volumes:
  db_data:

[DOCKER_COMPOSE_NAME]_[VOLUME_NAME]

docker run --rm \
  --volume [DOCKER_COMPOSE_PREFIX]_[VOLUME_NAME]:/[TEMPORARY_DIRECTORY_TO_STORE_VOLUME_DATA] \
  --volume $(pwd):/[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE] \
  alpine \
  tar cvf /[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE]/[BACKUP_FILENAME].tar /[TEMPORARY_DIRECTORY_TO_STORE_VOLUME_DATA]

docker run --rm \
  --volume chevereto_chevereto_data:/tmp \
  --volume $(pwd):/path_to_store_backup \
  alpine \
  tar cvf /path_to_store_backup/chevereto_chevereto_data.tar /tmp

docker run --rm \
  --volume [DOCKER_COMPOSE_PREFIX]_[VOLUME_NAME]:/[TEMPORARY_DIRECTORY_STORING_EXTRACTED_BACKUP] \
  --volume $(pwd):/[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE] \
  alpine \
  tar xvf /[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE]/[BACKUP_FILENAME].tar -C /[TEMPORARY_DIRECTORY_STORING_EXTRACTED_BACKUP] --strip 1

docker run --rm \
  --volume chevereto_chevereto_data:/tmp \
  --volume $(pwd):/path_to_store_backup \
  alpine \
  tar xvf /path_to_store_backup/chevereto_chevereto_data.tar -C /tmp --strip 1

docker exec [CONTAINER_NAME] /usr/bin/mysqldump -u root --password=root [DATABASE] > backup.sql

cat backup.sql | docker exec -i [CONTAINER_NAME] /usr/bin/mysql -u root --password=root [DATABASE]

curl -sSL https://get.docker.com | sh

sudo usermod -aG docker pi

FROM resin/rpi-raspbian:latest
ENTRYPOINT []

RUN apt-get update && \
    apt-get -qy install curl ca-certificates

CMD ["curl", "https://docker.com"]

FROM arm32v6/alpine:3.5

RUN apk add --no-cache curl ca-certificates

CMD ["curl", "https://docker.com"]

docker build -t curl_docker .
docker run curl_docker

gpu_mem=16