Overview



• Processes communicate via files

ps aux | grep udevd

# To view a list of file system
df -h


• In Ubuntu, you can run ifconfig from any user but not in Debian

# Examples
/sbin/ifconfig


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File System Layout


• Important directories for sysadmin
◇ /etc
▪ pronouced as “et - c”
▪ contains configuartion data for applications
- /etc/apt
- /etc/crontab
- /etc/ssh
◇ /sbin
▪ contains secured binaries, critical files
◇ /bin
▪ contains binaries of the base OS or links to binaries

• Others
◇ /dev
▪ contains all your devices
◇ /home
▪ home for all users that is not root
◇ /root
▪ /home directory for root
◇ /lib
◇ /lib64
▪ system libraries (like dll in windows)
◇ /media
▪ automatic mount
◇ /mnt
▪ manual mount
◇ /opt
▪ commercial programs e.g. dropbox
▪ packages not installed via package manager
▪ compiled programs
- make a link from /bin to /opt
◇ /proc
▪ kernel files (virutal fs)
▪ one directory for each process running on the machine
◇ /tmp
▪ clear when you reboot the machine
◇ /usr
▪ /usr/local
- compiled programs
▪ /usr/sbin
- system admin commands
▪ /usr/share
- configuration files, themes, icons, wallpapers, sound files
→ /usr/share/doc
⇒ documentation files
→ /usr/share/applications
⇒ .desktop files
◇ /var
▪ various files - files that change all the time
▪ /var/log - log files
◇ /lost+found
▪ found in ext4 file system

# Reference
# Descriptions of filesystem hierarchy
man hier


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File Types


• As shown in permission bits from ls command
◇ ordinary (-)
◇ links (l)
◇ directory (d)
◇ block device (b)
◇ character device (c)
◇ named pipes
◇ local sockets

ls -l /dev | grep sd            # show block device files
ls -l /dev/input/mouse0         # show character device file



Index