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sudo dd if=xxx.iso of=/dev/sdX bs=4M conv=fsync oflag=direct status=progress

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mkdir ~/.pip
cat <<EOF > ~/.pip/pip.conf

 [global]
 trusted-host =  mirrors.aliyun.com
 index-url = http://mirrors.aliyun.com/pypi/simple
EOF

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curl https://pyenv.run | bash
sudo apt install -y \
    wget \
    build-essential \
    libreadline-dev \
    libncursesw5-dev \
    libssl-dev \
    libsqlite3-dev \
    tk-dev \
    libgdbm-dev \

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openssl s_client -connect www.example.com:443 </dev/null 2>/dev/null | openssl x509 -inform pem -text

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gist of consistent hashing

Resolve rebalance problem of dynamic cluster. Key techniques:

• determine hash space, eg 2 * PI or 16K like redis
• map keys and nodes to the same hash space using hash function(s)
• keys are placed on the first node with hash value greater than the key, or on the first node
• use binary search tree to speed up locating the node for a paticular key
• when new node joins, move keys with hash value smaller than the new node from its successor to the node
• when existing node leaves, move keys on this node to its successor

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#!/bin/sh
# script to automate the creation of chroot jail
# w/ minimal executables to run git

export CHROOT=/var/chroot

function copy_binary() {
    for i in $(ldd $*|grep -v dynamic|cut -d " " -f 3|sed 's/://'|sort|uniq)
      do
        cp --parents $i $CHROOT

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git for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d

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cat <<EOF | (EDITOR="tee -a" visudo)
xxx         ALL=(ALL)       NOPASSWD: ALL
yyy         ALL=(ALL)       NOPASSWD: ALL
EOF

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openssl genrsa -out server.key 2048
openssl req -new -key server.key -out server.csr
openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

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SCRIPTPATH=$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)