My Tech Notes: linux

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Compress sparse files preserving their holes

use -S option for tar

tar -Sczvf sparse_file.tar.gz sparse_file

Find FIFO (named pipe) in Linux

 find ./ -type p

Find sparse files in Linux

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print}'

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print $2}'

To find and remove the sparse files:

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print $2}' | xargs rm -f

To find and compress the sparse files:

find ./ -type f -printf "%S\t%p\n" | awk '$1 < 1.0 {print $2}' | xargs -I {} sh -c "tar -Sczvf {}.tar.gz {}; rm -f {}"

SSH public key authentication rejected with debug message: no mutual signature algorithm

ssh user@remote-server -vvvv

debug1: no mutual signature algorithm

Cause

The RSA SHA-1 hash algorithm is being quickly deprecated across operating systems and SSH clients because of various security vulnerabilities, with many of these technologies now outright denying the use of this algorithm.

Solution

Generate SSH key using ED25519 algorithm:

ssh-keygen -t ed25519

Use GNU grep to count the length of substring between two words

Note: the command below requires GNU grep, it is available on Linux by default. On Mac OS, you need to install it manually using

brew install grep

and command is called ggrep instead of grep.

Get the substring between two words

echo "<person><name>abc</name></person>" | grep -o -P '(?<=<name>).*(?=</name>)'

Output should be:

abc

Count the length of substring

echo "<person><name>abc</name></person>" | grep -o -P '(?<=<name>).*(?=</name>)' | wc -c

Output should be:

Count substring lengths for each line

cat multi-lines.txt | while read line; do echo $line | grep -o -P '(?<=<name>).*(?=</name>)' | wc -c; done

Use grep to count number of occurs of a specific element in a single line XML text

For example, I can input.txt below, three lines of XML text, I want to count the number of id elements for each line:

<result><id>1</id><id>5</id><id>7</id></result>
<result><id>71</id></result>
<result><id>15</id><id>33</id></result>

I use grep -o:

cat input.txt | while read line; do echo $line | grep -o '<id>' | wc -l; done

The output should be:

3
1
2

Install Starcraft on Ubuntu Linux 22.04 LTS

1. Enable 32 bit (i386) arcitecture

sudo dpkg --add-architecture i386

2. Install wine-staging

Add WineHQ gpg key

wget -nv https://dl.winehq.org/wine-builds/winehq.key -O - | sudo apt-key add -

Add WineHQ repository

sudo add-apt-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ jammy main'
sudo apt update

Install winehq-staging

sudo apt install --install-recommends winehq-staging

wine-staging will be installed into /opt/wine-staging

3. Install required packages

sudo apt update
sudo apt install libgl1-mesa-glx:i386 libasound2:i386 libasound2-plugins:i386 libc6:i386 libncurses5:i386 libstdc++6:i386 libxtst6:i386 libldap-2.5-0:i386 libfreetype6:i386

4. Download StarCraft-Setup.exe

Download StarCraft-Setup.exe from https://us.battle.net/download/getInstaller?os=win&installer=StarCraft-Setup.exe

5. Install StarCraft

Run the commands below in a Terminal window to install StarCraft:

export WINEDLLPATH=/opt/wine-staging/lib/wine/fakedlls
export LD_LIBRARY_PATH="/opt/wine-staging/lib:$LD_LIBRARY_PATH"
WINEDEBUG=-all WINEPREFIX="${HOME}/.wine" /opt/wine-staging/bin/wine ./StarCraft-Setup.exe

While installation, you may be asked to install "Mono" and "Gecko" packages for the wine prefix.

6. Fix QT platform plugin error

Installation may be failed with error: This application failed to start because it could not find or load the QT platform plugin "Windows"

To work around this, you need to install attr package and use setfattr command to removed the atrribute: user.DOSATTRIB

6.1. Install attr package

sudo apt install attr

6.2. Remove file attribute

find "${HOME}/.wine/drive_c/Program Files (x86)/Battle.net" -name qwindows.dll -exec setfattr -x user.DOSATTRIB {} \;

setfattr -x user.DOSATTRIB "${HOME}/.wine/drive_c/Program Files (x86)/Battle.net/Battle.net.13894/platforms/qwindows.dll"

More details about this issue: see

6.3. Continue the installation

After removing the attribute, you can then continue the installation by executing the command below in the Terminal window:

WINEDEBUG=-all WINEPREFIX="${HOME}/.wine" /opt/wine-staging/bin/wine "${HOME}/.wine/drive_c/Program Files (x86)/Battle.net/Battle.net.exe"

7. Create StarCraft startup script

After installation, you can start StarCraft using the command below:

WINEDEBUG=-all WINEPREFIX="${HOME}/.wine" /opt/wine-staging/bin/wine "${HOME}/.wine/drive_c/Program Files (x86)/StarCraft/x86/StarCraft.exe"

You can also create a wrapper script at ~/.local/bin/starcraft and add contents below

#!/bin/bash
export WINEDLLPATH=/opt/wine-staging/lib/wine/fakedlls
export LD_LIBRARY_PATH="/opt/wine-staging/lib:$LD_LIBRARY_PATH"
WINEDEBUG=-all WINEPREFIX="${HOME}/.wine" /opt/wine-staging/bin/wine "${HOME}/.wine/drive_c/Program Files (x86)/StarCraft/x86/StarCraft.exe"

You need to make the script executable:

chmod +x ~/.local/bin/starcraft

You can now start StarCraft with command

starcraft

AND OR NOT operators for grep

grep OR

use '\|'
```
grep 'pattern1\|pattern2' file
```
use -E
```
grep -E 'pattern1|pattern2' file
```
use -e
```
grep -e pattern1 -e pattern2 file
```

grep AND

use pattern1.*pattern2

grep -E 'pattern1.*pattern2|pattern2.*pattern1' file

use multiple (piped) grep commands
```
grep pattern1 file | grep pattern2
```

grep NOT (invert) option

use -v option
```
grep -v pattern file
```

Install Chinese Input Method on Kubuntu 22.04

```
sudo apt install ibus-libpinyin
```
Right click IBus icon in the system tray, select Restart
Right click IBus icon in the system tray, select Preferences
In Preferences window, activate Input Method tab, click Add button, select Chinese, then Inteligent Pinyin

Install missing library for Cisco AnyConnect VPN client on Linux

After install Cisco AnyConnect VPN clinet on Kubuntu Linux, got the error when starting the application:

"You are missing the required libraries for the authentication method you requested"

To fix the issue, install the library: libwebkit2gtk-4.0-37

sudo apt install libwebkit2gtk-4.0-37

Install SimpleNote on Ubuntu Linux

Download SimpleNote for Linux from https://github.com/Automattic/simplenote-electron/releases/tag/v2.21.0

Install it:

sudo apt install ~/Downloads/Simplenote-linux-2.21.0-amd64.deb

Start SimpleNote:

/opt/SimpleNote/simplenote

It may fail to start with errors:

libva error: /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so init failed

Adding --disable-gpu-sandbox could work around the issue.
```
/opt/SimpleNote/simplenote --disable-gpu-sandbox
```

/usr/share/applications/simplenote.desktop also need to editted to add the arg:

[Desktop Entry]
Name=Simplenote
Exec=/opt/Simplenote/simplenote --disable-gpu-sandbox %U

Remove CTRL-M characters from a file in Linux or MacOS

You may need to do this when you import a text file from MS-DOS (or MS-Windows), and forget to transfer it in ASCII or text mode. Here are several ways to do it; pick the one you are most comfortable with.

The easiest way is probably to use sed to remove the ^M characters. Type this command:
```
% sed -e "s/^M//" filename > newfilename
```
To enter ^M, type CTRL-V, then CTRL-M. That is, hold down the CTRL key then press V and M in succession.
You can also do it in vi: % vi filename
Inside vi [in ESC mode] type: :%s/^M//g
To enter ^M, type CTRL-V, then CTRL-M. That is, hold down the CTRL key then press V and M in succession.
You can also do it inside Emacs. To do so, follow these steps:
Go to the beginning of the document
Type: M-x replace-string RET C-q C-m RET RET
where "RET" means <press the return key> and C-q and C-m mean <hold the CTRL key and press the m (or q) key>.

File name encoding on Linux

Linux File Name Encoding

check LANG environment variable
- echo $LANG
See also
- How to tell the language encoding
- Encoding of file names in Java

iocharset option of mount

iocharset=value
Character set to use for converting between 8 bit characters and 16 bit Unicode characters. 
The default is iso8859-1. Long filenames are stored on disk in Unicode format.

See also
- https://linux.die.net/man/8/mount

convmv - converts filenames from one encoding to another

https://linux.die.net/man/1/convmv

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Cause

Solution

See also

Get the substring between two words

Count the length of substring

Count substring lengths for each line

see also

1. Enable 32 bit (i386) arcitecture

2. Install wine-staging

3. Install required packages

4. Download StarCraft-Setup.exe

5. Install StarCraft

6. Fix QT platform plugin error

6.1. Install attr package

6.2. Remove file attribute

6.3. Continue the installation

7. Create StarCraft startup script

See also

grep OR

grep AND

grep NOT (invert) option

see also

See also

See also

see also

Linux File Name Encoding

iocharset option of mount

convmv - converts filenames from one encoding to another

See also

Install openconnect and openconnect-sso

Connect to VPN

Uninstall openconnect and openconnect-sso

See also

see alos