Disk

write iso to disk

dd if=os.img of=/dev/sdX bs=1M status=progress oflag=dsync

where - oflag=dsync - synchronize I/O for data.

RAM disk

sudo mount -o size=2G -t tmpfs none my.project.com

Mounted filesystems in nice layout

mount | column -t

Create Windows USB flash

1. Install WoeUSB
2. Unmount flash drive using Disks program
3. Write ISO

   bash woeusb-5.2.4.bash --device windows.iso /dev/sdc
   

4. Reboot and install Windows

ACL

Full access for two users

setfacl -R -d -m u:user1:rwx,u:user2:rwx .   # set default ACL for specific users
setfacl -R -m u:user1:rwx,u:user2:rwx .      # set ACL for specific users
setfacl -bn .                                # remove all extended ACL entries
setfacl -R -d -m g:media:rwx .               # default ACL for media group
setfacl -R -m g:media:rwx .                  # ACL for media group
getfacl .                                    # get file access control lists

Check read-only file systems

grep "[[:space:]]ro[[:space:],]" /proc/mounts

Source: serverfault.com

Groups

usermod -aG group_name user_name    # add group to user
newgrp group_name                   # activate the changes to groups