git-worktree

 

 Since 2015 git added a command git-worktree. This command could be used  when you have a repository  and each branch represent an old Versions of the code, one feature_branch or simple using the main branch.  This command generate a new tree, and you can avoid doing checkout on branches every  time you have to do an urgent bug fix or edit without doing changes on the main tree locally. 

Advantages.

•     the Time spent by you IDE to reindex the switched branch, so you save a little of Time If you use some jetbrains IDE or eclipse.
•     No need to fetch ,if you don't want to.
•     By each tree you Will have a new project in the IDE .
•     This command use a new directory un your file system, AND use the same .git/config file.
•     You could compare the code by tree, branches, and directories.

In the old fashion way you Will have to clone each repo in diferents directories, and check or set manually  same config on .git/config,  each directory Will be a project in you IDE. In this way you only could compare by directory and by branch.

Another way was use git stash to save what are you working on, and do the checkout to the branch version  with the bug on production, this way you have a Lot of context switch (to make an hotfix) , cos you Will need to do the reindex on you IDE (in case you use eclipse or some jetbrains IDE ), and later checkout to your branch_feature, unstash, AND again reindex, and always don't forget to clean cache!

Some examples:

(base) ┌─[j3nnn1@caracas] - [~/git/tools] - [Sun Nov 28, 13:26] └─[$] <git:(master)> git worktree add /home/j3nnn1/git/tools2 Preparing worktree (new branch 'tools2') Updating files: 100% (2887/2887), done. HEAD is now at db7534a Update paquetes.txt

When hotfix is ready and the fix it’s in production:

└─[$] <git:(master)> git worktree remove /home/j3nnn1/git/tools2

$ git worktree add <path> <branch>

With -d  throwaway working tree

git worktree prune

To clean up any stale administrative files.

git worktree lock

To not delete, remove, or prune when gc.worktreePruneExpire passes.

List all trees

└─[$] <git:(master)> git worktree list /home/j3nnn1/git/tools   db7534a [master] /home/j3nnn1/git/tools2  db7534a [tools2]

 

chezmoi saving your config files versioned

 

pacman -Syu chezmoi

chezmoi init (make a new dir  ~/.local/share/chezmoi)

chezmoi add ~/.bashrc

chezmoi [add|edit|update]  ~/.bashrc

chezmoi cd (~/.local/share/chezmoi)

git remote add origin https://github.com/j3nnn1/dotfiles.git

git branch -M main

git push -u origin main 

 

Additional config:

git config pull.ff true

git config pull.rebase true

and that's all.

udev events, making an udev rule and debugging rules.

udev is a device manager for the linux kernel.

when you connect some device (pendrive, camera, microphone) on a linux machine, you have a daemon listen to events that are fired when the kernel register a new device. All devices are mapped to a file on /dev so you could check some info about the device with this command:

udevadm info -a -n  /dev/DEVICE_NAME

i.e.: udevadm info -a -n  /dev/ttyUSB2

udevadm info -a -n  /dev/ttyUSB2 | grep '{devpath}' | head -n 1
udevadm info -a -n  /dev/ttyUSB2 | grep '{idVendor}' | head -n 1
udevadm info -a -n  /dev/ttyUSB2 | grep '{idProduct}' | head -n 1
udevadm info -a -n  /dev/ttyUSB2 | grep '{serial}' | head -n 1

knowing the device info we could make a rule based in the information and execute a new action: make a file, make a symlink or execute a script. For example I want to create a rule that match with the attributes devpath, idVendor, idProduct, serial and generate a new symlink.

we need to create a file into:

/etc/udev/rules.d/99-some-rule.rules

- in this file we need to use "" in the values.
- each line is a rule.
- each line has many or one attribute and one action. When the attributes matched  the action is executed, that's all.
- if you edit or create a new rule, you need to load and trigger all rules again.

udevadm control --reload-rules && udevadm trigger

- so sometimes is tricky check why some rule is not executed. For debug you have:

    - udevadm test /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.3/1-1.3:1.0/ttyUSB0/tty/ttyUSB0

      the devices path you could obtain with the comand udevadm info.

    - udevadm monitor

      show the events that are fired.
    
    - udevadm control --log-priority=debug

      set the environment on debug mode.

    - udevadm test $(udevadm info --query=path --name=ttyUSB0)
      
      test all rules associated to the device name ttyUSB0

- when you have an syntax error on some rules file, this will appear in the logs:
    - journalctl -f

- restart service:
    - systemctl restart systemd-udevd
 

- kernel messages
    - dmesg

- example: file called 99-new-rule.rules:

SUBSYSTEM=="tty", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", ATTRS{devpath}=="1.2", ATTRS{bcdDevice}=="0264", SYMLINK+="FANCY_NAME"

The 99 number indicated the priority for execution. in this case would be the last one to execute.

It's important to put double quotes instead single quote.