Hello World

假設用 linux crontab + tar 排程備份網站資料

# tar -zcpBf /home/backup/site1.tgz /var/www/html/site1/

備份出來的檔案會包含完整的路徑
var/www/html/site1/index.php
var/www/html/site1/robots.txt
var/www/html/site1/hello.jpg

但如果只想保留相對路徑，移除完整路徑
可改用以下參數
# tar -zcpBf /home/backup/site1.tgz -C /var/www/html/ site1/
site1/index.php
site1/robots.txt
site1/hello.jpg

tar -C 參數，先 cd 到該路徑，再執行備份指令
-C, --directory=DIR
Change to DIR before performing any operations.  This option is order-sensitive, i.e. it affects all options that follow.
 

新版 ubuntu 預設沒有 netstat 工具
取而代之的是 ss 指令

如果要使用 netstat 工具
請安裝 net-tools 套件

root@example:~# netstat -na

Command 'netstat' not found, but can be installed with:

apt install net-tools

root@example:~# apt install net-tools
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  net-tools
0 upgraded, 1 newly installed, 0 to remove and 5 not upgraded.
Need to get 196 kB of archives.
After this operation, 864 kB of additional disk space will be used.
Get:1 http://tw.archive.ubuntu.com/ubuntu focal/main amd64 net-tools amd64 1.60+git20180626.aebd88e-1ubuntu1 [196 kB]
Fetched 196 kB in 1s (262 kB/s)
Selecting previously unselected package net-tools.
(Reading database ... 115357 files and directories currently installed.)
Preparing to unpack .../net-tools_1.60+git20180626.aebd88e-1ubuntu1_amd64.deb ...
Unpacking net-tools (1.60+git20180626.aebd88e-1ubuntu1) ...
Setting up net-tools (1.60+git20180626.aebd88e-1ubuntu1) ...
Processing triggers for man-db (2.9.1-1) ...
root@example:~#

假設要移動特定檔名的檔案到某個資料匣，但是因為檔案數量太多出現以下錯誤訊息

[root@example testdir]# mv test-*.log /tmp/workdir/
-bash: /usr/bin/mv: Argument list too long

可以考慮 find 配合 xargs 實現
參考語法:
[root@example testdir]# /usr/bin/find /testdir/ -type f -name 'test-*.log' | /usr/bin/xargs  -I '{}' /usr/bin/mv '{}' /tmp/workdir/

以下狀況最近常發現在 FreeBSD 用戶端要讀取使用 Let's Encrypt. 憑證的網站



$ wget https://example.xx.xx/
Resolving example.xx.xx (example.xx.xx)... xx.xx.xx.xx
Connecting to example.xx.xx (example.xx.xx)|xx.xx.xx.xx|:443... connected.
ERROR: cannot verify example.xx.xx's certificate, issued by 'CN=R3,O=Let\'s Encrypt,C=US':
  Issued certificate has expired.
To connect to example.xx.xx insecurely, use `--no-check-certificate'.

$ curl https://example.xx.xx/
curl: (60) SSL certificate problem: certificate has expired
More details here: https://curl.haxx.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

原因是 client 的 ca root 憑證過期
以freebsd 為例，可以查看 /usr/local/etc/ssl/cert.pem

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            44:af:b0:80:d6:a3:27:ba:89:30:39:86:2e:f8:40:6b
    Signature Algorithm: sha1WithRSAEncryption
        Issuer: O=Digital Signature Trust Co., CN=DST Root CA X3
        Validity
            Not Before: Sep 30 21:12:19 2000 GMT
            Not After : Sep 30 14:01:15 2021 GMT
        Subject: O=Digital Signature Trust Co., CN=DST Root CA X3
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:

略過錯誤的解決方式:
$ wget --no-check-certificate https://example.xx.xx/
$ curl -k https://example.xx.xx/

如果是使用 apache 的 proxypass 
請在設定檔加入
SSLProxyEngine on
SSLProxyVerify none
SSLProxyCheckPeerCN off
SSLProxyCheckPeerName off
SSLProxyCheckPeerExpire off

重啟 apache 

發現系統出現以下錯誤訊息
Sep 30 14:12:57 s245 multipathd[601]: sda: add missing path
Sep 30 14:12:57 s245 multipathd[601]: sda: failed to get udev uid: Invalid argument
Sep 30 14:12:57 s245 multipathd[601]: sda: failed to get sysfs uid: Invalid argument
Sep 30 14:12:57 s245 multipathd[601]: sda: failed to get sgio uid: No such file or directory
Sep 30 14:13:02 s245 multipathd[601]: sda: add missing path
Sep 30 14:13:02 s245 multipathd[601]: sda: failed to get udev uid: Invalid argument
Sep 30 14:13:02 s245 multipathd[601]: sda: failed to get sysfs uid: Invalid argument
Sep 30 14:13:02 s245 multipathd[601]: sda: failed to get sgio uid: No such file or directory

解決方式
1. 將 guestos 先關機
2. 點擊 guestos 右鍵 -> 編輯設定 
3. 切換至 選項 -> 一般
4. 點擊右邊組態參數
5. 新增組態名稱和值分別為 disk.EnableUUID 及 TRUE
6. 確定，重開vm guestos



參考資料: https://ubuntuforums.org/showthread.php?t=2441797

執行 elastic search 需要有java 環境
請先確定系統環境是否已經安裝 java
$ java -version

如果沒有的話，以下步驟安裝
$ sudo apt install default-jre

設定環境變數
$ vi /etc/environment
JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64/"

$ source /etc/environment

安裝 elastic search 步驟
$ wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
$ sudo apt-get install apt-transport-https
$ echo "deb https://artifacts.elastic.co/packages/6.x/apt stable main" | sudo tee -a /etc/apt/sources.list.d/elastic-6.x.list
$ sudo apt-get update && sudo apt-get install elasticsearch
 

如果你有使用 cloudflare 的cdn 功能
預設的cache 是啟用的
但是如果你目前需要頻繁更新網頁
想要看到即時的畫面，又不要不斷的清cache 

cloudflare 提供了 development mode 的功能
啟用development mode 之後的三個小時內
cloudflare 會幫你bypass 所有的cache 
直到你手動關閉或是三個小時後自動關閉

另外也提供api 可以不用登入管理介面操作

example:
取得目前 development mode 狀態
curl -X GET "https://api.cloudflare.com/client/v4/zones/YOUR-ZONE-ID/settings/development_mode" \
     -H "X-Auth-Email: user@example.com" \
     -H "X-Auth-Key: YOUR-API-KEY" \
     -H "Content-Type: application/json"

回傳
{
  "success": true,
  "errors": [],
  "messages": [],
  "result": {
    "id": "development_mode",
    "value": "off",
    "editable": true,
    "modified_on": "2014-01-01T05:20:00.12345Z",
    "time_remaining": 3600
  }
}

啟用 development mode
curl -X PATCH "https://api.cloudflare.com/client/v4/zones/YOUR-ZONE-ID/settings/development_mode" \
     -H "X-Auth-Email: user@example.com" \
     -H "X-Auth-Key: YOUR-API-KEY" \
     -H "Content-Type: application/json" \
     --data '{"value":"on"}'

{
  "success": true,
  "errors": [],
  "messages": [],
  "result": {
    "id": "development_mode",
    "value": "on",
    "editable": true,
    "modified_on": "2014-01-01T05:20:00.12345Z",
    "time_remaining": 3600
  }
}

關閉 development mode
curl -X PATCH "https://api.cloudflare.com/client/v4/zones/YOUR-ZONE-ID/settings/development_mode" \
     -H "X-Auth-Email: user@example.com" \
     -H "X-Auth-Key: YOUR-API-KEY" \
     -H "Content-Type: application/json" \
     --data '{"value":"off"}'

{
  "success": true,
  "errors": [],
  "messages": [],
  "result": {
    "id": "development_mode",
    "value": "off",
    "editable": true,
    "modified_on": "2014-01-01T05:20:00.12345Z",
    "time_remaining": 3600
  }
}

Zone ID 可以在 overview 的左下角取得

API Key 可以再點進 Get your API token 後取得

ubuntu 20.04 預設重開機時無法啟用 /etc/rc.local
如果要重開機後執行的話，修改方式如下

1. 在檔案的最末端加入以下三行，存檔離開
sudo vi /lib/systemd/system/rc-local.service
[Install] 
WantedBy=multi-user.target
Alias=rc-local.service

2. 建立 rc.local
sudo vi /etc/rc.local
#!/bin/sh -e

echo `date` >> /tmp/reboot.log

exit 0

3. 加入可執行權限
sudo chmod u+x /etc/rc.local

4. 設定開機啟動，並手動啟用測試
sudo systemctl enable rc-local
sudo systemctl start rc-local

5. 檢視是否已啟用
sudo systemctl status rc-local
● rc-local.service - /etc/rc.local Compatibility
     Loaded: loaded (/lib/systemd/system/rc-local.service; enabled; vendor preset: enabled)
    Drop-In: /usr/lib/systemd/system/rc-local.service.d
             └─debian.conf
     Active: active (exited) since Fri 2021-09-17 01:53:56 UTC; 3s ago
       Docs: man:systemd-rc-local-generator(8)
    Process: 989234 ExecStart=/etc/rc.local start (code=exited, status=0/SUCCESS)

Sep 17 01:53:56 example systemd[1]: Starting /etc/rc.local Compatibility...
Sep 17 01:53:56 example systemd[1]: Started /etc/rc.local Compatibility.

6. 建立連結
sudo ln -s /lib/systemd/system/rc-local.service /etc/sysstemd/system/rc-local.service

7. 重開機
sudo reboot

相關連結:  透過 crontab 實現重開機時自動執行 script
https://helloworld.pixnet.net/blog/post/48872828-%e9%80%8f%e9%81%8e-crontab-%e5%af%a6%e7%8f%be%e9%87%8d%e9%96%8b%e6%a9%9f%e6%99%82%e8%87%aa%e5%8b%95%e5%9f%b7%e8%a1%8c-script

官網上提供詳細步驟
https://about.gitlab.com/install/#ubuntu

1. 安裝相關套件
sudo apt-get update
sudo apt-get install -y curl openssh-server ca-certificates tzdata perl

如果需要寄信的話，安裝MTA
sudo apt-get install -y postfix

2. 新增package repository 並安裝
curl https://packages.gitlab.com/install/repositories/gitlab/gitlab-ee/script.deb.sh | sudo bash

EXTERNAL_URL 改成你的gitlab 網址，需要dns 查詢的到或室 /etc/hosts 有綁定ip 也可以
sudo EXTERNAL_URL="https://gitlab.example.com" apt-get install gitlab-ee

3. 透過瀏覽器登入
網址列填入 https://剛剛你設定的網址/
預設帳號: root
密碼: 系統會隨機產生並保留24小時，在 /etc/gitlab/initial_root_password 可以找到

在shell 輸入 update-alternatives --config editor
星號標示目前預設的文字編輯器
如果要改變預設的文字編輯器，僅需要在提示欄位輸入編號即可
因為我習慣vi 的操作方式，所以我選擇3 並按enter 確認

root@helloworld:~# update-alternatives --config editor
There are 4 choices for the alternative editor (providing /usr/bin/editor).

  Selection    Path                Priority   Status
------------------------------------------------------------
* 0            /bin/nano            40        auto mode
  1            /bin/ed             -100       manual mode
  2            /bin/nano            40        manual mode
  3            /usr/bin/vim.basic   30        manual mode
  4            /usr/bin/vim.tiny    15        manual mode

Press <enter> to keep the current choice[*], or type selection number: 3
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/editor (editor) in manual mode

測試預設的編輯器是否生效
root@helloworld:~# visudo

編輯 logind.conf
# vi /etc/systemd/logind.conf

找到 HandleLidSwitch 關鍵字
把前面的註解拿掉
並修改為
HandleLidSwitch=ignore

存檔離開，重開機

 

情境:
1. ubuntu server 20.04 僅提供 AP (access poing ) 存取
2. client 透過 ubuntu sever 向 core router 提出 dhcp 請求

首先確認 ubuntu 的 有線和無線網卡均可正常運作
安裝以下必要套件
# apt -y install hostapd
# apt -y install bridge-utils

編輯 hostapd 設定檔
# vi /etc/hostapd/hostapd.conf
interface=wlan0
driver=nl80211
hw_mode=g
channel=1
ieee80211d=1
country_code=TW
ieee80211n=1
wmm_enabled=1
ssid=AP-NAME
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=passwordddd
wpa_key_mgmt=WPA-PSK
rsn_pairwise=CCMP

# vi /etc/default/hostapd
DAEMON_CONF="/etc/hostapd/hostapd.conf"

設定 netplan
# vi /etc/netplan/00-installer-config.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: no
    wlan0:
      dhcp4: no
  bridges:
    br0:
      interfaces:
        - eth0
        - wlan0
      addresses:
        - 10.10.10.247/24
      gateway4: 10.10.10.252
      nameservers:
        addresses: [10.10.10.26,8.8.8.8]

啟用 hostapd
# systemctl unmask hostapd
# systemctl start hostapd

最後找一台client 測試連線

Ubuntu Linux 20.04 網路設定由 netplan 管理
如果一開始設定是 dhcp client 的話，/etc/netplan/00-installer-config.yaml 設定類似如下

作業系統環境: ubuntu-20.04.2.0-desktop-amd64
無線網卡: 【EDIMAX 訊舟】EW-7822UAD AC1200 雙頻 長距離USB 3.0無線網路卡

1. 至官方網站下載 driver
https://www.edimax.com/edimax/download/download/data/edimax/global/download/product/wireless_adapters/wireless_adapters_ac1200_dual-band/ew-7822uad/

2. 解壓縮
# unzip EW-7822UAD_Linux_Driver_1.0.0.1.zip

3. 安裝 driver
安裝需要的套件套件
# apt-get update
# apt install net-tools make make-guile gcc

安裝驅動程式
# cd ./Linux/driver
# make && make install 

4. 重開機
# reboot

5. 檢查是否啟用
# ifconfig -a
查看是否多一個interface
 

執行 wifi up 
root@OpenWrt:/etc/config# wifi up

wifi status 觀察是否啟用，但"up": false,
root@OpenWrt:/etc/config# wifi status
{
        "radio0": {
                "up": false,
                "pending": false,
                "autostart": true,
                "disabled": false,
                "retry_setup_failed": true,
                "config": {
                        "channel": "11",
                        "hwmode": "11g",
                        "path": "pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0",
                        "htmode": "HT20"
                },
                "interfaces": [
                        {
                                "section": "default_radio0",
                                "config": {
                                        "mode": "ap",
                                        "encryption": "psk-mixed",
                                        "ifname": "wlan0",
                                        "wds": true,
                                        "ssid": "aptest",
                                        "key": "password",
                                        "network": [
                                                "lan"
                                        ],
                                        "mode": "ap"
                                }
                        }
                ]
        }
}

查看log，發現少了一個工具 ./mac80211.sh: eval: line 793: /usr/sbin/hostapd: not found
root@OpenWrt:/etc/config# logread | grep radio
Tue Aug 24 07:11:13 2021 daemon.notice netifd: radio0 (10651): command failed: Not supported (-95)
Tue Aug 24 07:11:13 2021 daemon.notice netifd: radio0 (10651): ./mac80211.sh: eval: line 793: /usr/sbin/hostapd: not found
Tue Aug 24 07:11:13 2021 daemon.notice netifd: radio0 (10651): cat: can't open '/var/run/wifi-phy0.pid': No such file or directory
Tue Aug 24 07:11:13 2021 daemon.notice netifd: radio0 (10651): WARNING (wireless_add_process): executable path /usr/sbin/hostapd does not match process  path (/proc/exe)
Tue Aug 24 07:11:13 2021 daemon.notice netifd: radio0 (10651): Command failed: Invalid argument
Tue Aug 24 07:11:13 2021 daemon.notice netifd: radio0 (10651): Device setup failed: HOSTAPD_START_FAILED
Tue Aug 24 07:11:29 2021 daemon.notice netifd: radio0 (10834): command failed: Not supported (-95)
Tue Aug 24 07:11:29 2021 daemon.notice netifd: radio0 (10834): ./mac80211.sh: eval: line 793: /usr/sbin/hostapd: not found
Tue Aug 24 07:11:29 2021 daemon.notice netifd: radio0 (10834): cat: can't open '/var/run/wifi-phy0.pid': No such file or directory
Tue Aug 24 07:11:29 2021 daemon.notice netifd: radio0 (10834): WARNING (wireless_add_process): executable path /usr/sbin/hostapd does not match process  path (/proc/exe)
Tue Aug 24 07:11:29 2021 daemon.notice netifd: radio0 (10834): Command failed: Invalid argument
Tue Aug 24 07:11:29 2021 daemon.notice netifd: radio0 (10834): Device setup failed: HOSTAPD_START_FAILED

安裝 hostapd
root@OpenWrt:/etc/config# opkg install hostapd
Installing hostapd (2019-08-08-ca8c2bd2-7) to root...
Downloading http://downloads.openwrt.org/releases/19.07.8/packages/x86_64/base/hostapd_2019-08-08-ca8c2bd2-7_x86_64.ipk
Configuring hostapd.

重新啟用 wifi
root@OpenWrt:/etc/config# wifi up

確認是否正常啟用
root@OpenWrt:/etc/config# wifi status
{
        "radio0": {
                "up": true,
                "pending": false,
                "autostart": true,
                "disabled": false,
                "retry_setup_failed": false,
                "config": {
                        "channel": "11",
                        "hwmode": "11g",
                        "path": "pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0",
                        "htmode": "HT20"
                },
                "interfaces": [
                        {
                                "section": "default_radio0",
                                "config": {
                                        "mode": "ap",
                                        "encryption": "psk-mixed",
                                        "ifname": "wlan0",
                                        "wds": true,
                                        "ssid": "aptest",
                                        "key": "password",
                                        "network": [
                                                "lan"
                                        ],
                                        "mode": "ap"
                                }
                        }
                ]
        }
}
 

1. 首先找一台linux ，並提升至 root 權限，至 https://www.finnix.org/Download 下載最新版的 iso 
目前最新版本為 122
# cd /workdir/
# wget https://www.finnix.org/releases/122/finnix-122.iso

2. 掛載 iso 檔
mkdir /mnt/finnixiso
# mount -o loop /workdir/finnix-122.iso /mnt/finnixiso
# mkdir /workdir/myfinnix-122

3. 因為mount 上來的iso 是唯讀狀態，所以我們要複製一份檔案至 /workdir/myfinnix-122
# rsync -a /mnt/finnixiso/ /workdir/myfinnix-122/

4. 解壓檔案系統
#  cd /workdir/myfinnix-122/isolinux/live
# unsquashfs filesystem.squashfs

5. 這時候可以將需要的檔案放進解壓縮出來的檔案系統
# cd squashfs-root/home/

例如，把 openwrt-19.07.8-x86-64-combined-ext4.img 放進 ./home/openwrt/
# mkdir openwrt
# cd openwrt/
# cp /path/openwrt-19.07.8-x86-64-combined-ext4.img .

6. 重新壓縮檔案系統
# cd /workdir/myfinnix-122/isolinux/live
# rm -r filesystem.squashfs
# mksquashfs squashfs-root filesystem.squashfs
#  rm -rf squashfs-root

7. 製作 iso 檔
# cd ../
# genisoimage -l -r -J -V "myfinnix-122" -b isolinux/isolinux.bin -no-emul-boot -boot-load-size 4 -boot-info-table -c isolinux/boot.cat -o ../myfinnix-122.iso ./

以上步驟即可完成客製化 finnix livecd

也可以利用 rufus 工具將客製化 iso 製作成開機 usb 隨身碟

1. 安裝 haproxy
# cd /usr/ports/net/haproxy
# make install clean 

2. 安裝完後不會自動產生預設的設定檔，所以要自己建立
# vi /usr/local/etc/haproxy.conf

global
    daemon
    maxconn 4096

defaults
   log global
   mode http
   timeout connect 5s
   timeout client 10s
   timeout server 10s

#以mysql 為例
listen mydb
bind 0.0.0.0:3306
mode tcp
balance roundrobin
server db11 192.168.2.11:3306 check
server db11 192.168.2.12:3306 check

# web 管理介面，可以透過這個網址檢視backend 狀態
listen webinterface
bind 0.0.0.0:8080
mode http
stats enable
stats uri /
stats realm Strictly\ Private
stats auth admin:12345 #這邊分別是登入的帳號:密碼

3. 設定重開機時，自動啟用 haproxy
# /usr/local/etc/rc.d/haproxy enable

4. 第一次手動啟動 haproxy
# /usr/local/etc/rc.d/haproxy onestart

Linux mount windows 分享的資料匣指令如下
1. 建立 Linux 本機目錄
mkdir /mnt/windir

2. 掛載分享空間，帳號密碼，及路徑依需求調整
mount -t cifs -o username=user1,password=a12345678 "\\\192.168.1.10\MY DIR" /mnt/windir/

3. 查看是否 mount 成功
df -h

4. 卸載
umount /mnt/windir

linux server 跑久了之後，系統時間難免會有誤差
以前的習慣是執行 ntpdate [ntp-server]
發現 CentOS 沒有這個 ntp client 的指令
[root@example ~]# ntpdate time.stdtime.gov.tw
-bash: ntpdate: command not found

所以試試用 yum 安裝 ntp 套件，喔喔，找不到這個套件!!??
[root@example ~]# yum  -y install ntp
Last metadata expiration check: 0:02:43 ago on Mon 02 Aug 2021 11:00:28 AM CST.
No match for argument: ntp
Error: Unable to find a match: ntp

原來 CentOS 8 要安裝 chrony 套件來取代 ntp
[root@example ~]# yum -y install chrony
Last metadata expiration check: 0:04:50 ago on Mon 02 Aug 2021 11:00:28 AM CST.
Dependencies resolved.
=========================================
 Package            Architecture    Version               Repository       Size
=========================================
Installing:
 chrony             x86_64          3.5-2.el8             baseos          270 k
Installing weak dependencies:
 timedatex          x86_64          0.5-3.el8             baseos           32 k

Transaction Summary
=========================================
Install  2 Packages

Total download size: 302 k
Installed size: 580 k
Downloading Packages:
(1/2): chrony-3.5-2.el8.x86_64.rpm              8.5 MB/s | 270 kB     00:00
(2/2): timedatex-0.5-3.el8.x86_64.rpm           235 kB/s |  32 kB     00:00
--------------------------------------------------------------------------------
Total                                           265 kB/s | 302 kB     00:01
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                        1/1
  Installing       : timedatex-0.5-3.el8.x86_64                             1/2
  Running scriptlet: timedatex-0.5-3.el8.x86_64                             1/2
  Running scriptlet: chrony-3.5-2.el8.x86_64                                2/2
  Installing       : chrony-3.5-2.el8.x86_64                                2/2
  Running scriptlet: chrony-3.5-2.el8.x86_64                                2/2
  Verifying        : chrony-3.5-2.el8.x86_64                                1/2
  Verifying        : timedatex-0.5-3.el8.x86_64                             2/2

Installed:
  chrony-3.5-2.el8.x86_64               timedatex-0.5-3.el8.x86_64

Complete!

修改 /etc/chrony.conf , 改成你習慣的 ntp server
[root@example ~]# vi /etc/chrony.conf
#pool 2.centos.pool.ntp.org iburst
server time.stdtime.gov.tw iburst

重啟 chronyd 服務
[root@example ~]# systemctl restart chronyd

完成
 

1. 建立帳號密碼檔
1.1 初次建立，或是想清空之前紀錄，請加參數 -c
htpasswd -c /etc/httpd/.htpasswd user1
New password: <輸入user1的密碼>
Re-type new password: <確認密碼>
Adding password for user user1

1.2 接著建立第二位以上的user，千萬不要加參數 -c 
htpasswd /etc/httpd/.htpasswd user2
New password: <輸入user1的密碼>
Re-type new password: <確認密碼>
Adding password for user user2

2. 編輯 .htaccess
2.1 假設網站路徑是 /var/www/html/admin
vi /var/www/html/admin/.htaccess
AuthName "admin login"
AuthUserFile /etc/httpd/.htpasswd
AuthType Basic
require valid-user

開啟網頁測試，正確的話，會跳出一個帳號密碼對話框
輸入剛剛建立的帳號密碼即可登入