Linux basics session 2
Linux user environment
Ubuntu provides a decent graphical user interface (GUI) with most common applications available from Free Open Source Software (FOSS) sources. Window Manager (called Gnome in Ubuntu) is running on top X Server which is an ordinary daemon (service). Underlying system can always be controlled using a console - Terminal - Command Line Interface (CLI). Linux servers powering the majority of Internet sites don't have GUI installed unlike Windows servers.
Desktop
SUPER key (WIN key or COMMAND on Mac) to access "spotlight", start typing to open applications.
web browser - FireFox
PRINT SCREEN key - creates a screenshot into Pictures folder - combine with SHIFT for a snip
Calculator, LibreOffice Calc (Excel alternative)
Nautilus (files) - browsing files - home folder structure
installing programs (graphical mainly)
graphical editors - Gimp (raster graphics), Inkscape (Vector graphics)
communicators available: Slack, Teams, Skype, WhatsApp, Messenger, Telegram, ...
Remina - remote desktop
FileZilla - FTP - file transfers
openscad - 3D modeling
terminal - command line window - shell - Bash for Ubuntu - shortcut CTRL+ALT+T
Command Line Interface (CLI)
All the time use TAB key to autocomplete your command or file path - it saves time and prevents typos!
whoami, id, who - users, groups
uptime, date - time info
cal -jy 1750 - calendar - anatomy of a command: '
man cal - manual pages - documentation - how to read Usage section
for any command you don't know start with man <command> or <command> --help or <command> -h
What is my HW configuration?
free - memory info
cat /proc/cpuinfo - cpu info - command cat prints out the content of a file
df -h - disk usage info
cat /etc/issue - Linux distribution and version
uname -a - Linux kernel version and build architecture
Network configuration:
ip a l - shows IP addresses on network devices - ip address list in full - modern style of providing arguments to commands
route - routing table
hostname -f - full hostname of the machine (doesn't work well for our test machines)
Filesystem Hierarchy Standard (see Linux Brief presentation):
Everything in Linux is a file mounted under "/" (root of filesystem), unlike C: drive, E: drive, ... in Windows
Administrator user is always called "root", it's home folder is in "/root/", other users have their home directories in "/home/
Daemons (services) have configuration in "/etc/" and logs under "/var/log/".
Working in the home directory:
pwd - print current directory
ls, ls -la - file listing, hidden files starts with ".", owner, group, permissions
ls ./Downloads - relative path
ls /home/vasek/Downloads - absolute path
cd Download - change directory
cd .. - one directory up
mkdir test - create new directory
rmdir test - remove directory
touch test.txt - create empty file
rm test.txt - remove file
mv test.txt test2.txt - move or rename file - "-i" to not accidentally overwrite existing file
alias mv=mv -i adding "-i" to mv command by default
Linux command line cheat sheet: linux_cheat_sheet.pdf - from fosswire.com
Self-study
Mastering linux is mainly about mastering keyboard input, practice makes perfect.
Use the command line exclusively. In your home folder create a directory structure with files as follows.
HINT: use mkdir for directories and touch for files.
Stretch goal: instead of creating empty files, create proper content or find suitable examples on-line and put them in place (command wget for download, mv for moving/renaming file).
Solution
$ mkdir -p work/project_A/images
$ mkdir -p work/project_A/images
$ mkdir -p work/project_A/data
$ mkdir -p work/project_b
$ mkdir -p work/project_X
$ touch work/project_X/idea.txt
$ touch work/project_b/draft.doc
$ touch work/project_A/README.txt
$ touch work/project_A/data/sample.csv
$ touch work/project_A/images/01.jpg
$ tree work/
work/
├── project_A
│ ├── data
│ │ └── sample.csv
│ ├── images
│ │ └── 01.jpg
│ └── README.txt
├── project_b
│ └── draft.doc
└── project_X
└── idea.txt
5 directories, 5 files