linux mid exam ubuntu

# unix mid exam ubuntu ## Mounting a new partition first, add disk to VM use fdisk to partition ```shell $ sudo fdisk /dev/sdb ``` press `n` to create a new storage then, press`w` to save ur change use `mkfs` ```shell $ sudo mkfs -t ext4 /dev/sdb1 ``` > [!Tip] > **`mkfs`** is the abbrevation of **M**a**k**e **F**ile **S**ystem finally, use `mount` to mount the disk to dir ```shell $ sudo mount /dev/sdb1 /home/mnt1 ``` to check if mounting successful ```shell $ lsblk ``` > [!Tip] > **`lsblk`** is the abbrevation of **L**i**s**t **Bl**oc**k** ### Auto mounting on startup add disk uuid to the `/etc/fstab` > [!Tip] > **`fstab`** is the abbrevation of **F**ile **S**ystem **Tab**le find disk uuid ```shell $ lsblk -f ``` copy uuid and go to `/etc/fstab` ```shell $ sudo vim /etc/fstab ``` if u have not installed `vim` yet, use apt command ```shell $ sudo apt install vim ``` add a new line ``` UUID=<uuid> <mount_dir> ext4 default 0 1 ``` then, press `Escape` and type `:wq` in order to check whether disk is auto mounting or not, we need to reboot our system ```shell $ sudo reboot ``` or shutdown and restart ```shell $ sudo shutdown now ``` finally, use `lsblk` to check this is mounting or not ## Create new user ```shell $ sudo adduser b ``` ## Add user to sudoers ```shell $ sudo visudo ``` :::spoiler 📝 Example: give user b `apt` permission 1. run visudo 2. add b to allow apt command ```diff root ALL=(ALL) ALL + b ALL=(ALL) NOPASSWD: /usr/bin/apt ``` ::: :::spoiler 📝 Example: give user multiple command permission 1. run visudo 2. add b to allow `apt` and `vim` command ```diff root ALL=(ALL) ALL + b ALL=(ALL) NOPASSWD: /usr/bin/apt, /usr/bin/vim ``` ::: to check self permission ```shell $ sudo -l ``` if not have any sudo permission, u cannot do this search command path ```shell $ which apt ``` ## Change File Permissions create a new folder under `/home` folder ```shell $ sudo mkdir share ``` and change folder to uself ```shell $ sudo chown 'u name':'u name or share grp name' /share ``` and craete a cpp file ```shell $ cd share $ vim a.cpp $ g++ ./a.cpp -o a ``` give file permission ```shell $ chmod g+w /share/a.cpp $ chmod o+xs /share/a ``` | scope | operator | permission | | -------------- | -------- | -------- | | `u` file owner `g` group `o` others `a` all | `+` add `-` remove `=` set | `r` read `w` write `x` execute `s` setuid | switch to user b and check it ![91tiRtwMXsL](https://hackmd.io/_uploads/SJxJWxKWke.jpg) good luck