Last year's stuff

bash_course/.gitignore

+*.toc
+*.log
+*.aux
+*.nav
+*.snm
+*.out
+*.pdf
+*.synctex.gz
+
+*.vrb
+
+*~
+*.swp
+
+
+guide/bashguide.html

bash_course/TODO

+- Reformulate PATH exercise for increased security and decreased chance of bricking system
+- Meditate over the brightness script

bash_course/buildall.sh

+#!/bin/bash
+
+echo 'Guide'
+(
+    cd guide
+    ./build.sh | sed 's/^/- /'
+)
+echo 'Presentation'
+(
+    cd pres
+    ./build.sh | sed 's/^/- /'
+)
+echo 'Exercise sheet'
+(
+    cd exercisesheet
+    ./build.sh | sed 's/^/- /'
+)

bash_course/exercisesheet/build.sh

+#!/bin/bash
+echo "Building exercises pdf..."
+pandoc sheet.md --listings --toc -V links-as-notes -H listings-setup.tex -o sheet.pdf \
+    && echo "Build successful"
+echo "Building solutions pdf..."
+pandoc sol.md --listings -H listings-setup.tex -o sol.pdf \
+    && echo "Build successful"

bash_course/exercisesheet/listings-setup.tex

+\usepackage{xcolor}
+\usepackage[margin=2cm]{geometry}
+
+%various gray colors
+\definecolor{slg}{gray}{0.25}
+\definecolor{lg}{gray}{0.55}
+\definecolor{vlg}{gray}{0.73}
+\definecolor{tlg}{gray}{0.9}
+
+
+%TheAlt colors
+\definecolor{ldorange}{HTML}{F18A20}
+\colorlet{ldbright}{ldorange!70!white} % tinted version of orange
+\definecolor{ldblue}{HTML}{254471}
+
+%%Theme colors
+%\definecolor{thgreen}{HTML}{A1A92C}
+%\definecolor{thmauve}{HTML}{97284D}
+
+%Theme colors
+\definecolor{thgreen}{HTML}{539727}
+\definecolor{thmauve}{HTML}{572272}
+
+
+\lstdefinestyle{custombash}{
+    belowcaptionskip=1\baselineskip,
+    captionpos=,
+    breaklines=true,
+    frame=L,
+    xleftmargin=\parindent,
+    language=bash,
+    morestring=[b]',
+    morekeywords=[2]{sudo,zypper,notify-send,feh,youtube-dl,sort,tee,head,tail,shuf,mpv,find,convert,xrandr,curl,wget,grep,xdotool,rm,cp,mv,touch,bash,chmod,mkdir,rsync,mplayer,mpv,xdotool,jshon},
+    showstringspaces=false,
+    basicstyle=\scriptsize\ttfamily,
+    rulecolor=\color{tlg},
+    backgroundcolor=\color{tlg},
+    fillcolor=\color{tlg},
+    rulesepcolor=\color{tlg},
+    commentstyle=\itshape\color{thmauve!60!black},
+    keywordstyle=\bfseries\color{thgreen},
+    identifierstyle=\color{ldblue},
+    stringstyle=\color{thmauve},
+}
+
+
+\lstset{
+    basicstyle=\ttfamily,
+    backgroundcolor=\color{black!10},
+    showspaces=false,
+    showstringspaces=false,
+    showtabs=false,
+    tabsize=2,
+    captionpos=b,
+    breaklines=true,
+    breakatwhitespace=true,
+    breakautoindent=true,
+    linewidth=\textwidth,
+    style=custombash
+}
+

bash_course/exercisesheet/sol.md

+# Master solutions 
+## Your first script
+
+    #!/bin/bash
+    echo 'Hello, World!'
+
+## Count to 100
+
+Make sure the parameter expansion is quoted properly. It may not be necessary here, but it is good practice.
+
+    #!/bin/bash
+    for i in {1..100}
+    do
+        echo "$i"
+    done
+
+Here, we use brace expansion, so we can't use quotes.
+
+    #!/bin/bash
+    echo {1..100}
+
+## Set up a script directory for your user
+
+The following line should be added to either `~/.profile` or `~/.bashrc`. You have to log out and back in to make it work.
+
+    export PATH="$PATH:/home/user/scripts"
+
+You can test whether it worked by running
+
+    echo "$PATH"
+
+in your terminal.
+
+## Parse some options
+
+    #!/bin/bash
+	while getopts 'h?abc:' opt; do
+		case "$opt" in 
+		h|\?)
+			echo 'Available options: -h, -a, -b, -c ARGUMENT'
+			exit 0
+			;;
+		a)
+			echo 'Option a selected'
+			;;
+		b)
+			echo 'Option b selected'
+			;;
+		c) 
+			echo "Option f selected with argument $OPTARG"
+			;;
+		esac
+	done
+
+	shift $((OPTIND-1))
+
+The shift line at the end is important! If you have more arguments (that aren't options), you can't access them otherwise.
+
+## Output all your arguments
+
+	#!/bin/bash
+	for i in "$@"
+	do
+		echo "$i"
+	done
+
+Make sure all quotes are put correctly. Especially the expression `"$@"` MUST be quoted.
+
+## Find big files
+
+	#!/bin/bash
+
+	usage() {
+		echo "usage: $0 directory"
+		exit 1
+	}
+
+	# We want exactly one argument
+	if [[ "$#" -ne 1 ]]; then
+		usage
+	fi
+
+	dir="$1"
+
+    # Test whether argument is a directory
+	if ! [[ -d "$dir" ]]
+    then
+		usage
+	fi
+
+    # Find files in dir, sort by size and print largest 5
+	find "$dir" -printf '%s %p\n' | sort -nr | head -n 5
+
+The use of a function for `usage` is not required, but it's good practice.
+
+## Self-reproducing script
+
+    #!/bin/bash
+    cp "$0" backup.sh
+
+
+This second example also works, but is bad practice: it is discouraged to use `cat` to get the contents of a file in a bash script. There are almost always better ways to do that.
+
+    #!/bin/bash
+    cat "$0" > backup.sh
+
+
+## Make your bash prompt fancy
+
+Not much to say here, all solutions will be individual
+
+## Maze generator
+
+`RANDOM` is an environment variable that takes on a different numeric value every time you read it.
+
+    #!/bin/bash
+    while true
+    do 
+        (( $RANDOM % 2 ))  \
+            && echo -n '/' \
+            || echo -n '\' \
+        sleep 0.07
+    done
+
+## Simple backup script
+
+The `find` option `-type f` makes sure only files are listed (and not directories). The `-ctime -1` option makes sure only files not older than 1 day (24 hours) are listed.
+
+	#!/bin/bash
+	find . -type f -ctime -1 | xargs tar -czf 'backup.tar.gz'
+
+## Screen brightness control
+
+	#!/bin/bash
+
+	(( $# == 0 )) && {
+		echo "No argument given; exiting"
+		exit 1;
+	}
+
+	# -z tests whether string is empty (zero length). We search for + or - in the string.
+	if [[ -z $( echo $1 | grep -Eo "\+|-" ) ]]
+	then
+		newbrightness="$1"
+	else
+		brightness="$(cat /sys/class/backlight/intel_backlight/brightness)"
+		newbrightness="$(( $brightness $1 ))" # becomes for example 10 +1
+	fi
+
+	# prevent screen from going all black. The threshold value might vary,
+	# since the scale of brightness values is different on every system
+	if (( $newbrightness < 10 ))
+	then
+		newbrightness=10
+	fi
+
+	# use tee instead of redirections because we need sudo
+	echo "$newbrightness" | sudo tee /sys/class/backlight/intel_backlight/brightness > /dev/null
+
+The file path might of course vary. If you don't find a brightness file in `/sys/class/backlight`, chances are this script is not possible on your system.
+
+## Automatic update script
+
+This script is designed to be used with `sudo`, i.e. `sudo updatescript`. If you use it like that, you don't need `sudo` for zypper inside the script.
+
+    #!/bin/bash
+    # First, move old files out of the way safely. Discard error messages.
+    mv -b /home/user/updatelog /home/user/updatelog-old > /dev/null 2>&1
+
+    { zypper up > /home/user/updatelog } \
+        && rm /home/user/updatelog
+
+    poweroff
+
+Of course, the zypper command is for openSUSE, and other distros require other commands.
+
+## Disable/Enable external monitor output
+
+These are some examples. It depends on your setup what you need.
+	
+	#!/bin/bash
+	xrandr --output HDMI-0 --auto --left-of LVDS-0
+	
+<!-- -->
+
+	#!/bin/bash
+	xrandr --output HDMI-0 --auto
+	xrandr --output LVDS-0 --off
+
+<!-- -->
+
+	#!/bin/bash
+	# detect a monitor
+	if xrandr | grep 'HDMI-0 connected' > /dev/null
+	then
+		xrandr --output HDMI-0 --right-of LVDS-0
+	fi
+
+## Display a random headline from Reddit
+
+This exercise requires you to parse strings to display them nicely. That can be quite tedious, and the commands used for it are often cryptic (cf. `sed`). Don't be scared.
+
+    #!/bin/bash
+    curl -A 'Mozilla/5.0 (Windows; U; MSIE 7.0; Windows NT 6.0; en-US)' -s https://www.reddit.com/r/showerthoughts.json \
+        | jshon -e data -e children -a -e data -e title \
+        | shuf -n 1 \
+        | sed 's/\\//g' \
+        | sed 's/^"//' \
+        | sed 's/"$//'
+
+The three `sed`s are merely for pretty printing. The first removes backslashes, the second removes the first quote and the last removes the last quote.
+
+In a `sed` expression, `^` matches the beginning of a line and `$` matches the end. Also, backslashes (among other characters) have to be *escaped* using yet another backslash.
+
+## Wallpaper change every 10 minutes
+
+You can run this script in the background, like this: `./wallpaperscript &`
+
+	#!/bin/bash
+	while true
+	do
+		feh --bg-fill --randomize ~/pictures/wallpaper/*
+		sleep $(( 60 * 10 ))
+	done
+
+## Your own TODO program
+
+	#! /bin/bash
+	# use a subshell to contain the directory change
+	(
+		# we work in .config, this isn't mandatory. ~/.config is where many
+        # programs store user configuration.
+		mkdir -p ~/.config/todo
+		cd ~/.config/todo
+		touch todolist # touch creates a file if it doesn't exist yet
+
+		while getopts 'i:d:h' opt; do
+			case "$opt" in
+				h|\?)
+					echo 'Valid flags: -i -d -h'
+					;;
+				i)
+					echo "$OPTARG" >> todolist
+					;;
+				d)
+					# sed '3d' deletes the 3rd line from a file.
+					sed -e "${OPTARG}d" todolist > /tmp/todolist
+					cp /tmp/todolist todolist
+					;;
+			esac
+		done
+		# the -n option adds line numbers
+		cat -n todolist
+	)
+
+## Reminder script
+
+	#!/bin/bash
+    mins="$1"
+    shift 1
+
+    echo notify-send "'$@'" | at now + "$mins" min &>/dev/null
+    echo "Reminder: $@ set for $mins mins from now."
+
+## Youtube downloader
+
+	#!/bin/bash
+	
+	query="$@"
+
+	# get youtube search results page 
+	# search for links that contain 'watch\?v=' followed by 11 characters
+	# take the first one
+	ytid=$( \
+		curl -s --data-urlencode "search_query=$query" https://www.youtube.com/results \
+		| grep -oE 'watch\?v=.{11}' \
+		| head -n 1 \
+	)
+
+	echo "$ytid"
+
+	youtube-dl -f bestaudio -o "%(title)s_%(id)s.%(ext)s" "https://www.youtube.com/$ytid"
+
+## Web radio
+
+	#!/bin/bash
+
+	# tidy up first
+	killall mpv
+
+	# The & is not required but useful. Cache size is increased for lag free streaming
+	mpv http://213.251.190.165:9000 -cache 1024 &
+
+## Image resizer
+
+	#!/bin/bash
+
+	mkdir -p resized
+
+	for i in *
+	do
+		# The > indicates that ImageMagick should only shrink larger images 
+		convert "$i" -resize '100x100>' resized/"$i"
+	done
+
+
+## Assignment-fetcher
+
+	#!/bin/bash
+
+	while getopts 'h?lf:u:p:' opt; do
+		case "$opt" in 
+		h|\?)
+			echo "usage: $0 [-l] [-f FILTER] [-u USER] [-p PASSWORD] URL"
+			exit 0
+			;;
+		f) 
+			filter="$OPTARG"
+			;;
+		u)
+			user="$OPTARG"
+			;;
+		p)
+			pass="$OPTARG"
+			;;
+		l) 
+			list=true
+		esac
+	done
+
+	shift $((OPTIND-1))
+
+	url=$1
+
+	
+	# Bare url up to the first slash. 
+    # The grep first finds all characters up to the first dot, and then from there on finds
+    # all characters that are NOT slashes up to the first slash.
+    # The sed is used to escape all slashes within the url. / becomes \/
+	baseurl=$( \
+		echo $url \
+		| grep -oe '.*\.[^/]*/' \
+		| sed -e 's/\//\\\//g' \
+	)
+
+	# URL without file name (up to the last slash). 
+    # The grep just finds everything up to a slash. By default it uses greedy matching,
+    # which means that it finds the longest fitting sequence.
+    # The sed is used to escape all slashes within the url.
+	longurl=$( \
+		echo $url \
+		| grep -oe '.*/' \
+		| sed -e 's/\//\\\//g' \
+	)
+
+    # The last command used in the command chain below depends on an option.
+	# if -l was passed, we just echo the found pdfs. Otherwise download them.
+	if [ $list == true ]
+	then
+		# the -n option is for xargs
+		lastcmd="-n 1 echo"
+	else
+		lastcmd="wget --user $user --password $pass"
+	fi
+
+	# First, find strings that end in .pdf
+	# Then, prepend the base url to all strings that are relative urls
+	# Then, apply the filter
+	# Then, if an url starts with // (relative to root), prepend the longurl
+	# last, download or display the urls
+	curl -s $url \
+		| grep -oe '[^"]*\.pdf' \
+		| sed -e "s/^\//$baseurl\//" 
+		| grep -e "/[^/]*$filter[^/]*\.pdf" \
+		| awk "{ if ( \$0 !~ /\/\// ) { print \"$longurl\" \$0 } else {print} }" 2>/dev/null \
+		| xargs $lastcmd

bash_course/guide/build.sh

+#!/bin/bash
+echo "Building pdf..."
+pandoc guide.md --listings --toc -N -V links-as-notes -H listings-setup.tex -o guide.pdf \
+    && echo "Build successful"
+
+echo "Building html..."
+pandoc --toc -N --template template.html --highlight-style tango guide.md | sed 's/<code>/<code class="prettyprint">/g' > bashguide.html \
+    && echo "Build successful"

bash_course/guide/listings-setup.tex

+\usepackage{xcolor}
+\usepackage[margin=2cm]{geometry}
+
+%various gray colors
+\definecolor{slg}{gray}{0.25}
+\definecolor{lg}{gray}{0.55}
+\definecolor{vlg}{gray}{0.73}
+\definecolor{tlg}{gray}{0.9}
+
+
+%TheAlt colors
+\definecolor{ldorange}{HTML}{F18A20}
+\colorlet{ldbright}{ldorange!70!white} % tinted version of orange
+\definecolor{ldblue}{HTML}{254471}
+
+%%Theme colors
+%\definecolor{thgreen}{HTML}{A1A92C}
+%\definecolor{thmauve}{HTML}{97284D}
+
+%Theme colors
+\definecolor{thgreen}{HTML}{539727}
+\definecolor{thmauve}{HTML}{572272}
+
+
+\lstdefinestyle{custombash}{
+    belowcaptionskip=1\baselineskip,
+    captionpos=,
+    breaklines=true,
+    frame=L,
+    xleftmargin=\parindent,
+    language=bash,
+    morestring=[b]',
+    morekeywords=[2]{sudo,zypper,notify-send,feh,youtube-dl,sort,tee,head,tail,shuf,mpv,find,convert,xrandr,curl,wget,grep,xdotool,rm,cp,mv,touch,bash,chmod,mkdir,rsync,mplayer,mpv,xdotool,jshon},
+    showstringspaces=false,
+    basicstyle=\scriptsize\ttfamily,
+    rulecolor=\color{tlg},
+    backgroundcolor=\color{tlg},
+    fillcolor=\color{tlg},
+    rulesepcolor=\color{tlg},
+    commentstyle=\itshape\color{thmauve!60!black},
+    keywordstyle=\bfseries\color{thgreen},
+    identifierstyle=\color{ldblue},
+    stringstyle=\color{thmauve},
+}
+
+
+\lstset{
+    basicstyle=\ttfamily,
+    backgroundcolor=\color{black!10},
+    showspaces=false,
+    showstringspaces=false,
+    showtabs=false,
+    tabsize=2,
+    captionpos=b,
+    breaklines=true,
+    breakatwhitespace=true,
+    breakautoindent=true,
+    linewidth=\textwidth,
+    style=custombash
+}
+

bash_course/guide/template.html

+<div id="bashnav" class="left">
+<div id="bashnav-scroll">
+<div id="bashnav-wrap">
+$toc$
+</div>
+</div>
+</div>
+<div id="bashguide">
+<?prettify?>
+$body$
+</div>

bash_course/pres/build.sh

+#!/bin/bash
+echo "Building pdf..."
+pandoc -t beamer --template template.tex --listings pres.md -o pres-part.pdf --pdf-engine pdflatex \
+    && pandoc -t beamer --template template.tex --listings firstslide.md -o firstslide.pdf --pdf-engine pdflatex \
+    && pdfunite firstslide.pdf pres-part.pdf pres.pdf \
+    && rm firstslide.pdf pres-part.pdf \
+    && echo "Build successful"

bash_course/pres/firstslide.md

+# Welcome to the Bash Workshop!
+
+  * If you prefer to work on your own, already know programming or are confident in your abilities, please **sit in the back**.
+
+<!-- -->
+
+ * If you prefer guided exercises, are completely new to programming, or want to have your hands held, please **sit in the front**.
+

bash_course/pres/header.tex

+\usepackage[T1]{fontenc} %pipes don't display properly without this
+\usepackage[utf8]{inputenc}
+\usepackage{listings}
+\usepackage{color}
+\usepackage{datapie}
+\usepackage{multicol}
+\usepackage{siunitx} %pretty measurement unit rendering
+\usepackage{hyperref} %enable hyperlink for urls
+\usepackage{caption} % needed to tweak caption size
+
+
+\usefonttheme[onlymath]{serif}
+\setcounter{MaxMatrixCols}{20}
+
+\DeclareSIUnit\pixel{px}
+
+\usecolortheme[RGB={37,68,113}]{structure}
+\usetheme{Dresden}
+
+\newenvironment{figurehere}
+{\def\@captype{figure}}
+{}
+\makeatother
+
+%commands to exclude sections from miniframes
+\makeatletter
+\let\beamer@writeslidentry@miniframeson=\beamer@writeslidentry
+\def\beamer@writeslidentry@miniframesoff{%
+   	\expandafter\beamer@ifempty\expandafter{\beamer@framestartpage}{}% does not happen normally
+   	{%else
+   		% removed \addtocontents commands
+   		\clearpage\beamer@notesactions%
+   	}
+}
+\newcommand*{\miniframeson}{\let\beamer@writeslidentry=\beamer@writeslidentry@miniframeson}
+\newcommand*{\miniframesoff}{\let\beamer@writeslidentry=\beamer@writeslidentry@miniframesoff}
+\beamer@compresstrue
+\makeatother
+
+
+%various gray colors
+\definecolor{slg}{gray}{0.25}
+\definecolor{lg}{gray}{0.55}
+\definecolor{vlg}{gray}{0.73}
+\definecolor{tlg}{gray}{0.9}
+
+%TheAlt colors
+\definecolor{ldorange}{HTML}{F18A20}
+\colorlet{ldbright}{ldorange!70!white} % tinted version of orange, used in miniframes
+\definecolor{ldblue}{HTML}{254471}
+
+%reduce caption font size:
+\captionsetup{font={scriptsize,color=lg}}
+
+%do not prepend numbering/lettering to figures/subfigures
+\captionsetup{labelformat=empty} %do not prepend letters to figure captions
+
+%Apply TheAlt colors to theme
+ % section titles in top navigation bar
+\setbeamercolor{section in head/foot}{parent=palette tertiary,fg=ldorange}
+\setbeamertemplate{section in head/foot shaded}{\color{ldbright}\usebeamertemplate{section in head/foot}}
+ % miniframes (little navigation circles)
+\setbeamercolor*{mini frame}{fg=ldorange,bg=ldbright}
+\setbeamertemplate{mini frame in other section}[default][0]
+\setbeamertemplate{mini frame in other subsection}[default][0]
+ % others
+\setbeamercolor{author in head/foot}{fg=white}
+\setbeamercolor{subsection in head/foot}{fg=white}
+\setbeamercolor{caption name}{fg=vlg}
+\setbeamercolor{caption}{fg=vlg}
+\setbeamercolor{frametitle}{fg=ldblue}
+
+\setbeamertemplate{caption}{\raggedright\insertcaption\par}
+\setbeamertemplate{navigation symbols}{}
+\setbeamertemplate{bibliography item}[text]
+
+\definecolor{mygreen}{rgb}{0,0.6,0}
+\definecolor{mygray}{rgb}{0.5,0.5,0.5}
+\definecolor{mymauve}{rgb}{0.58,0,0.82}
+
+\lstdefinestyle{custombash}{
+	belowcaptionskip=1\baselineskip,
+	captionpos=,
+	breaklines=true,
+	frame=L,
+	xleftmargin=\parindent,
+	language=bash,
+	showstringspaces=false,
+	basicstyle=\scriptsize\ttfamily,
+	rulecolor=\color{tlg},
+	backgroundcolor=\color{tlg},
+	fillcolor=\color{tlg},
+	rulesepcolor=\color{tlg},
+	commentstyle=\itshape\color{purple!60!black},
+	keywordstyle=\bfseries\color{ldorange!80!black},
+	%keywordstyle=\bfseries\color{green!40!black},
+	identifierstyle=\color{blue},
+	stringstyle=\color{orange},
+}
+
+\lstset{language=Bash,style=custombash,caption={Descriptive Caption Text},label=DescriptiveLabel}
+
+\title{Bash Workshop}
+\author{Aline Abler}
+
+\institute{\includegraphics[width=0.35\textwidth]{img/logo_blue.pdf}}