_     _                  
| |   (_)_ __  _   ___  __
| |   | | '_ \| | | \ \/ /
| |___| | | | | |_| |>  < 
|_____|_|_| |_|\__,_/_/\_\

Sysfs Notes

  • Link: https://www.kernel.org/doc/ols/2005/ols2005v1-pages-321-334.pdf
  • Notes: Sysfs
  • For action with Lid or powerbutton with systemd-logind
Edit /etc/systemd/logind.conf and make sure you have

HandleLidSwitch=ignore
which will make it ignore the lid being closed. (You may need to also undo the other changes you've made.)

Then, you'll want to reload logind.conf to make your changes go into effect (thanks to Ehtesh Choudhury for pointing this out in the comments):

systemctl restart systemd-logind
  • For disabling linux laptop keyboard
You can use xinput to float the input device under X.

Execute the command xinput list to list your input devices.
Locate AT Translated Set 2 keyboard and take note of its id number; this will be used to disable the keyboard. Also, take note of the number at the end, [slave keyboard (#)]; this is the id number of the master, which will be used to re-enable your keyboard.
To disable the keyboard, execute the command xinput float <id#>, where <id#> is your keyboard's id number. For example, if the id was 10, then the command would be xinput float 10.
To re-enable the keyboard, execute the command xinput reattach <id#> <master#>, where master is that second number we noted down. So if the number was 3, you would do xinput reattach 10 3.

Remaking Grub entry

  • In case grub got borked somehow
sudo mkdir -p /mnt/boot/efi
sudo mount /dev/sda1 /mnt/boot/efi
cd /mnt/boot/efi
cat Recovery.txt
cd efi
sudo grub-install --target=x86_64-efi --efi-directory=/mnt/boot/efi
sudo grub-install --target=x86_64-efi --efi-directory=/mnt/boot/efi --bootloader-id=grub
sudo grub-mkconfig -o /mnt/boot/efi
os-prober
sudo os-prober

Importing a CA cert in Arch

Use the trust command provided by the p11-kit package:

sudo trust anchor --store ~/my-ca-cert.crt

## Source: https://unix.stackexchange.com/questions/373492/installing-certificates-on-arch

Sending Notifications from Cron

Simply add this to your crontab -e

# From stack overflow
# https://unix.stackexchange.com/questions/560724/unable-to-send-notifications-from-cron-job
DISPLAY=":0.0"
XAUTHORITY="/home/me/.Xauthority"
XDG_RUNTIME_DIR="/run/user/1000"
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus

Deleted files taking up space

  • Space not being freed from disk after deleting a file in Linux

This mostly happens because rm unlinks the file, but filesystem doesn’t reflects the changes. Which leads to taking up of space, even though the files have been deleted.

So as to check for it, simply run lsof | grep "deleted" This will show the files list and then you can manually do any of these:

  1. Restart the system
  2. Restart the process
  3. Truncate the file from proc memory location, this allows dealing with issue much more effectively. ``` root@pewpewnotes # lsof | grep -i deleted tuned 778 root 7u REG 202,2 4096 0 8827610 /tmp/ffikEo5nz (deleted)

root@pewpewnotes # file /proc/778/fd/7 /proc/778/fd/7: broken symbolic link to /tmp/ffikEo5nz (deleted)

root@pewpewnotes # > /proc/778/fd/7 truncate -s 0 /proc/778/fd/7


### Fixing Touchpad on i3wm

git clone https://github.com/Trumeet/X-Touch-Touchpad cd X-Touch-Touchpad makepkg -ci reboot


### Setting Up auto mount at boot

`Created by Jay Ta'ala, last modified on Nov 02, 2021`

*Guide to mount a drive in linux (deb/ubuntu) and set to auto-mount at boot.*

* Mount drive
* Make a folder (will be mount point)

sudo mkdir /media/data sudo mount /dev/sdb1 /media/data Now you can access the drive at /media/data.

*** 
#### Auto-mount at boot
We want the drive to auto-mount at boot.  This usually means editing /etc/fstab.

* Firstly, it's always best to use the drives UUID.  To find the drive's UUID do

`ls -al /dev/disk/by-uuid/`
* Copy the resultant UUID (for your disk) and then open fstab for editing (note I'm using vim here but use whatever editor you prefer):

`sudo vim /etc/fstab`
You want to add an entry for the UUID and mount point.  Below is an example of an fstab file with an entry added for the mount above:

/etc/fstab: static file system information.

#

Use ‘blkid’ to print the universally unique identifier for a

device; this may be used with UUID= as a more robust way to name devices

that works even if disks are added and removed. See fstab(5).

#

/ was on /dev/sdb1 during installation

UUID=63a46dce-b895-4c1f-9034-b1104694a956 / ext4 errors=remount-ro 0 1

swap was on /dev/sdb5 during installation

UUID=b9b9ee49-c69c-475b-894b-1279d44034ae none swap sw 0 0

data drive

UUID=19fa40a3-fd17-412f-9063-a29ca0e75f93 /media/data ext4 defaults 0 0 Note: the entry added is the last line.


#### Test fstab
* We always want to test the fstab before rebooting (an incorrect fstab can render a disk unbootable).  To test do:

findmnt –verify check the last line for errors. Warnings can help in improving your fstab.

Unmounting drive with umount
You can unmount drives using umount.  For example, to unmount the data drive above mount at /media/data you would do:

sudo umount /media/data

#### Make java applications look good
* Just import these

export _JAVA_OPTIONS=’-Dawt.useSystemAAFontSettings=gasp’


### Redirecting Everything to NULL
* Here:

By default:

stdin ==> fd 0 stdout ==> fd 1 stderr ==> fd 2 In the script, you use > /dev/null causing:

stdin ==> fd 0 stdout ==> /dev/null stderr ==> fd 2 And then 2>&1 causing:

stdin ==> fd 0 stdout ==> /dev/null stderr ==> stdout ```

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