vnc for preview using raspistill

1. Click top right VNC icon:
   
2. Click the top right setting in VNC server windows:
   
3. Select Options:
   
4. In Options window, select Troubleshooting:
   
   
5. Turn on  Enable direct capture mode :
   
6. 
7. Done.
   

wifi password

Because wpa_supplicant.conf contains readable wifi passwords, it can be replaced by the psk unreadable codes. 

cf: https://raspberrypi.stackexchange.com/questions/91616/wpa-supplicant-conf-in-raspberry-pi-3

1. Run wpa_passphrase "chiao-dlink842"
2. Enter password, e.g. aaa123456, Press enter

1. Some lines come out. e.g.
network={
    ssid="chiao-dlink842"
    #psk="aaa123456"
         key_mgmt=WPA-PSK
    psk=<codes>
}
3. Delete the line with #psk="aaa123456", Then, add the rest lines to  /etc/wpa_supplicant/wpa_supplicant.conf
4. Done.
5. Also, for one (or some) of the AP not connected automatically, one can add this:
disabled=1

記憶體的功能分類

cf: https://isite.tw/2016/05/20/15923

• ECC: 錯誤更正能力
• Buffered or Registered: 暫存緩衝的功能 (Registered)

1. Non-ECC Unbuffered DIMM: 一般個人電腦使用的就是這種記憶體，價格最為低廉，但是既不具備錯誤更正能力，也沒有暫存緩衝的功能ECC 
2. Unbuffered DIMM: 比起 Non-ECC Unbuffered DIMM 來說，多了一顆記憶體顆粒
3. ECC Registered DIMM: 除了錯誤更正能力，還加入了暫存器緩衝區的設計，目前 Intel 只有 Xeon E5 處理器搭配伺服器主機版才能使用這類記憶體。

 

PCIE speed

sudo lspci -vv | grep -E 'PCI bridge|LnkCap|LnkSta:' 

00:1b.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #21 (rev f0) (prog-if 00 [Normal decode])
        LnkCap:    Port #21, Speed 8GT/s, Width x4, ASPM L0s L1, Exit Latency L0s <1us, L1 <16us
        LnkSta:    Speed 8GT/s (ok), Width x4 (ok)
00:1c.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #8 (rev f0) (prog-if 00 [Normal decode])
        LnkCap:    Port #8, Speed 8GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <1us, L1 <16us
        LnkSta:    Speed 5GT/s (downgraded), Width x1 (ok)
        LnkCap:    Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L1 <8us
        LnkSta:    Speed 8GT/s (ok), Width x4 (ok)
        LnkCap:    Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <4us, L1 unlimited
        LnkSta:    Speed 5GT/s (ok), Width x1 (ok)

Check pcie gen3 or gen4 gen version

sudo lspci -vv | grep -E 'PCI bridge|LnkCap|LnkSta:' 

 

 

PCI Express 3.0
PCI-SIG 的 PCI Express 3.0 規格,新版每條 Lane 的單向頻寬增到 8Gbps.
但因為編碼方式改變了,相較於 2.0 之前採用 8b/10b (每10個bit只有8個是有效資料)而 3.0 編碼方式為 128/130,所以資料傳輸頻寬以及原始傳輸率基本當都可以算成 8Gbps.
x1 8Gbps (1GB/sec)
x4 32Gbps (4 GB/sec)
x8 64Gbps (8 GB/sec)
x16 128Gbps (16 GB/sec)

PCI-E 4.0 x4 ，提供最高 16GT/s×4=8GB/s 頻寬，

是 Gen3 NVMe SSD （ 8GT/s×4 =4GB/s ）

PCIE Gen	year		原始 傳輸率	頻寬（每個方向）
				×1	×2	×4	×8	×16
1.0	2003		2.5 GT/s	250 MB/s	0.50 GB/s	1.0 GB/s	2.0 GB/s	4.0 GB/s
2.0	2007		5.0 GT/s	500 MB/s	1.0 GB/s	2.0 GB/s	4.0 GB/s	8.0 GB/s
3.0	2010		8.0 GT/s	984.6 MB/s	1.97 GB/s	3.94 GB/s	7.88 GB/s	15.8 GB/s
4.0	2017		16.0 GT/s	1969 MB/s	3.94 GB/s	7.88 GB/s	15.75 GB/s	31.5 GB/s
5.0	2019		32.0 GT/s	3938 MB/s	7.88 GB/s	15.75 GB/s	31.51 GB/s	63.0 GB/s
6.0	2021		64.0 GT/s	7877 MB/s	15.75 GB/s	31.51 GB/s	63.02 GB/s	126.03 GB/s

Shrink the image file from dd

 cf: https://www.pragmaticlinux.com/2020/12/how-to-clone-your-raspberry-pi-sd-card-in-linux/

1. Download pishrink from GitHub 
2. pishrink pi4.img
3. (optional) gzip 9 pi4.img

Remove ibus input method 輸入法

cf: https://askubuntu.com/questions/860780/how-to-remove-old-ibus-keyboard-input-menu-items 

Enter dconf-editor and go to org.gnome.desktop.input-sources.sources then delete the input method not needed, e,g, ('ibus', 'fuzzy_table')

Inquiry about paper staus

 cf: https://www.editage.com/insights/how-do-i-write-an-inquiry-to-the-editor-about-my-manuscripts-current-status

Dear Mr./Ms. XXX [Editor's Name],

I have submitted my revised manuscript titled XXXX [manuscript id: xxxx] to your journal via the online submission system on dd/mm/yyyy [date of submission]. Two days later, the status changed to ‘with editor.’ However, the status has remained unchanged ever since.

I would be grateful if you could let me know whether there has been any further progress on my submission.

Sincerely,

XXXX [Your name and contact details]

Clean /var/log/journal

cf: https://j7.lb168.tw/2019/07/vacuum-var-log-journal/

1. sudo vim /etc/systemd/journald.conf
2. Add the lines:

3. SystemMaxUse=10M
   SystemMaxFileSize=10M

4. sudo systemctl restart systemd-journald.service

cf: https://askubuntu.com/questions/1238214/big-var-log-journal 

1. sudo journalctl --vacuum-size=10M
2. sudojournalctl --vacuum-time=10d

Configure Thunderbird for localhost

 cf :  https://gist.github.com/raelgc/6031274

1. 帳號設定　->　新增其他帳號　->　Unix Mailspool(Movemail)(U)
2. 您的大名: chiao
3. 電子郵件地址: chiao@localhost
4. 寄件伺服器: localhost

As of Thunderbird 87beta.x.x, Movemail support is removed. 

https://www.thunderbird.net/en-US/thunderbird/87.0beta/releasenotes/ 

Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"?

cf: https://stackoverflow.com/questions/54184707/warning-continue-targeting-switch-is-equivalent-to-break-did-you-mean-to-u

 

 Error while exporting excel from FAHP online system:

Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /usr/share/php/OLE.php on line 319

sudo vim +319 /usr/share/php/OLE.php

Change "continue" to "continue 2" as follows:

  default:
#chiao, 2021-12-5               
#                continue;
                continue 2;