Console Tricks Seminar

# Reset example files and folders
cd ${HOME}
mkdir -p exampledirectory1 exampledirectory2
rm -f exampledirectory?/*
rm -f examplefile2
echo "File1" > exampledirectory1/file1
echo "File2" > exampledirectory1/file2
echo "File3" > exampledirectory1/file3
echo -e "This Is Line1\nThis Is Line2\nThis Is Line3\nThis Is Line4" > examplefile
chmod 755 exampledirectory1 exampledirectory2
chmod 644 examplefile

Outline / TODO

1. Theory: What is a shell etc.
2. Getting Started: The Basics
   • filesystem hierarchy standard
   • ls, pwd, cd
   • man
   • File permissions, chmod
   • Editing and listing files: vi (nano), less, cat
   • Basic file operations: cp, mv, rm
3. Bash
   • Readline, shell history
   • Environment variables, expansion & substitution
   • Globbing
   • Basic scripting
     • hashbang line
     • basic control structures
   • Standard streams, Redirection, Pipes
     • pv (pipe viewer)
   • background jobs
4. Tasks & Tools
   • Text wrangling with sed, grep, cut & co
   • tmux / screen
   • Searching things: find, grep -R, etc.
   • Monitoring/processes: htop, pgrep, pkill, ...
   • xargs
   • netcat (use case: simple file copy with tar -c FILES | pv | nc foo 2342 --> nc -l 2342 | tar -x)
     • (OpenBSD netcat vs. GNU netcat ??)
   • Advanced SSH usage: public keys, forwarding (-L, -R, -D), per-host config, ProxyCommand, etc.
   • scp, rsync & co
   • curl / wget
   • networking tools: ping, traceroute, ip, whois, dig, ...
   • fuser, lsof, netstat

1. Introduction: What Is a Shell?

Confused?

Maybe this looks more like what you expected:

But is that a shell?

Yes and no. Let's have a look at the definition of a shell:

In computing, a shell is a user interface for access to an operating system's services. In general, operating system shells use either a command-line interface (CLI) or graphical user interface (GUI), depending on a computer's role and particular operation. Wikipedia

Maybe you wouldn't expect it, but the Windows Desktop, including the Windows Explorer, is a shell (and Microsoft actually calls it so).

On Linux systems we usually mean CLIs (command-line interfaces) when we're talking about shells. That doesn't mean that there aren't graphical shells. The X window system + your desktop environment is also a shell.

Back to our Linux “shell”…

What we see here are actually two things:

• A graphical terminal emulator
• A shell command prompt

The terminal window is basically a software version of this little fellow here: a very modern VT100 terminal (therefore the name “terminal emulator”).