Learned about vertical tabs today…
3 Likes
We all love ls but what if you want a tree like view, just type:
ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//--/g' -e 's/^/ /' -e 's/-/|/'
Enjoy your output.
1 Like
Nice use of the cascading sed substitutions!
1 Like
Maze Game
I created a timed maze game that reads a player defined map using arbitrary text. Has hit detection and a timed win condition.
Add an X for the player, an E for the exit, spaces are where the player can travel and anything else blocks movement.
I’ve been working with arrays so much the idea popped into my head so I put it into code. You can copy/paste in any text based map you find on the Internet (so long as traversable areas are spaces) and the script will make it work. Just add an X for the player and E for exit.
#!/usr/bin/env bash
#
# === USER DEFINED MAP ===
#
# Map key:
# - X for the player
# - E for exit
# - Space for traversable
# - Any other character blocks the player's movement
{ MAP_DATA=$(</dev/stdin); } <<\EOF
Movement: AWSD or HJKL
█████████████████████████/E\█
█ █ █ █
█ █ █ █ █ █ █ █
█ █ █ █ █ █ █ █
█ █ █ █████ █ █ █
█ █ █ █ █
█ █ █████████ █████ █
█ █ █ █ █ █
█ █████ █ █ █ █████
█ █ █ █
█████ █████████████ █ █
█ █ █ █ █ █
█ █ █ █ █ █████ █
█ X █ █ █
█ ^ █████████████████████████
EOF
# === DEFINE FUNCTIONS ===
MOVE_PLAYER(){
# Define where the player is attempting to move
ATTEMPT_X=$(( $1 + $PLAYER_X ))
ATTEMPT_Y=$(( $2 + $PLAYER_Y ))
ATTEMPT_MAP_Y_LINE=${MAP_Y[$ATTEMPT_Y]}
# Prevent out of bounds travel
if [ "$ATTEMPT_X" = "-1" -o "$ATTEMPT_Y" = "-1" ]; then return 1; fi
# Is the player moving onto a win condition?
if [ "${ATTEMPT_MAP_Y_LINE:$ATTEMPT_X:1}" = "E" ]; then
# Get the finish time, print victory statement and exit
FINISH_TIME=$(( SECONDS - GAME_START ))
printf "You escaped in %s seconds" $FINISH_TIME
if [ $PLAYER_Y == 0 ]; then printf " using \e[0;91mrule 0\e[0m"; fi
printf "!\n\n"
exit 1
fi
# Is the player attempting to move into an empty space?
if [ "${ATTEMPT_MAP_Y_LINE:$ATTEMPT_X:1}" = $EMPTY_BLOCK ]; then
# Erase current player location
PLAYER_MAP_Y_LINE=${MAP_Y[$PLAYER_Y]}
MAP_Y[$PLAYER_Y]="${PLAYER_MAP_Y_LINE:0:$PLAYER_X}${EMPTY_BLOCK}${PLAYER_MAP_Y_LINE:$(($PLAYER_X+1))}"
# Move player coordinates
PLAYER_X=$ATTEMPT_X
PLAYER_Y=$ATTEMPT_Y
# Draw new player location on updated and/or different PLAYER_MAP_Y_LINE
PLAYER_MAP_Y_LINE=${MAP_Y[$PLAYER_Y]}
MAP_Y[$PLAYER_Y]="${PLAYER_MAP_Y_LINE:0:$PLAYER_X}X${PLAYER_MAP_Y_LINE:$(($PLAYER_X+1))}"
# Print map
PRINT_MAP
fi
}
PRINT_MAP(){
clear
#printf '\e[0;92m' # Make green
printf '%s\n' "${MAP_Y[@]}"
#printf '\e[0;0m' # Reset color
}
USER_INPUT_LOOP(){
# Wait for the user to press a key and define it as $KEY
read -s -n 1 KEY
# Move the player according to the KEY's associated movement value in KEY_TO_MOVEMENT
MOVE_PLAYER ${KEY_TO_MOVEMENT[$KEY]}
USER_INPUT_LOOP
}
# === STARTUP ===
# Declare human input keys with movement modifiers
declare -A KEY_TO_MOVEMENT=( [w]="0 -1" [d]="1 0" [a]="-1 0" [s]="0 1" [k]="0 -1" [l]="1 0" [h]="-1 0" [j]="0 1" )
EMPTY_BLOCK="." # Special ANSI invisible character
IFS_OLD="$IFS";
IFS=""
# Replace all spaces with the EMPTY_BLOCK to simplify sequencing and add map to MAP_Y array.
MAP_DATA=$(echo $MAP_DATA | sed "s/ /$EMPTY_BLOCK/g")
readarray -t MAP_Y <<< "$MAP_DATA"
# Get player location by counting prior new lines and prior characters on the player's MAP_Y line.
PLAYER_Y=$(( `echo ${MAP_DATA%X*} | wc -l` - 1 ))
PLAYER_X=$(( `echo ${MAP_Y[$PLAYER_Y]%X*} | wc -m` -1 ))
IFS="$IFS_OLD"
GAME_START=$SECONDS
PRINT_MAP
USER_INPUT_LOOP
ncat: Hosting a public website with a single command
sudo dnf install nmap-ncat # Fedora/CentOS/RHEL
sudo apt install ncat # Debian/Ubuntu
ncat -klp 8080 --send-only -c 'printf "HTTP/1.1 200 OK\n\n%s" "<html><body><h1>Terminal Tuesday !!</h1></body></html>";'
# (Ctrl-C to quit)
# Options in use:
# -k, --keep-open Accept multiple connections in listen mode
# -l, --listen Bind and listen for incoming connections
# -p, --source-port port Specify source port to use
# --send-only Only send data, ignoring received; quit on EOF
# -c, --sh-exec <command> Executes the given command via /bin/sh
# Test in another terminal or Web browser:
curl http://127.0.0.1:8080
curl http://YOUR_LAN_OR_PUBLIC_IP:8080
Other Examples:
Similar to rm -rf these scripts are a great way to get yourself in trouble. Close off port 8080 on your firewall before playing, think before you type, know that any website can send you to a local address like 127.0.0.1:8080 in a hidden iframe and consider security is hard even for sysadmins.
# Introducing option: --allow <host>
# Allow only given hosts to connect to Ncat
# Return all environment variables accessible to the process (yikes)
ncat -klp 8080 --allow 127.0.0.1 --send-only -c 'printf "HTTP/1.1 200 OK\n\n"; printenv;'
# Run a local script and return the output (yikes)
ncat -klp 8080 --allow 127.0.0.1 --send-only -c 'printf "HTTP/1.1 200 OK\n\n"; ./run.sh;'
# Return an HTML page
ncat -klp 8080 --send-only -c 'printf "HTTP/1.1 200 OK\n\n"; cat ./index.html;'
# IP Lookup Server:
ncat -klp 8080 --send-only -c 'printf "HTTP/1.1 200 OK\n\n%s" "$NCAT_REMOTE_ADDR";'
# More ncat env variables: https://secwiki.org/w/Ncat/Environment_variables
Bash can look very sexy sometimes:
for n in {1..5}; do echo $n; done
And the output:
1
2
3
4
5
1 Like
Something I learned recently…
If any amount of leading zeros are added, the output will always be equal to the maximum number of possible digits.
for n in {01..10000}; do echo $n; done
00001
00002
…
09999
10000
for n in {1..010000}; do echo $n; done
000001
000002
…
009999
010000
2 Likes
This might be the coolest usage of an old terminal with a modern Linux machine I have yet seen. This is purely entertainment but something I have watched more than once, purely for the smiles.
This is part 2 where it is actually being employed.
For what it is worth, he is using Kubuntu for his Linux distribution.
Because it isn’t nice to just post a part 2, here is the Part 1
6 Likes
If this worked with Fusion 360… (insert dream sequence here)…
1 Like
If Fusion360 was fully supported on Linux by Autodesk… (insert dream sequence here)…
That video made me want to check out openSCAD, any time I can do something from the terminal I’m all in. So far it is really neat. Thanks for sharing!
2 Likes
I think I need to try to understand openSCAD too. It’s on the list… but not high on the list.
I use openSCAD – it just requires you to break an object down into shapes that produce the whole. I think one of the best features of it is that it’s parametric. You can search scad files on thingiverse – I have discovered some mind-blowing mathematical functions – which reminded me that there are people in the world who have forgotten more math than I have ever known.
what does a simple part, like a screw, look like? or a keyboard cap for example?
I’ll first show you the simplicity of the code with this very simple design of a push pin for the plastic inner fender for a car. The parametric nature of openSCAD allows me to return to the code and change a variable easily and with great precision.
// Push Rivet for Car
// Mark Cain
// August 22, 2020
// Revision 0.3 //
// Revision 0.2 // measurements in mm height=16, cone_base=14, cone_tip=6
// Revision 0.1 // measurements in mm height=20, cone_base=15, cone_tip=5
cone_base = 14;
cone_height = 16;
cone_tip = 6;
ring_elevation = 6;
ring_height = 4;
connector_height =10;
rotate([0, 0 , 0]){
difference() {
union() { // beginning of the visible union
cylinder(h=cone_height, d1=cone_base, d2=cone_tip);
}; // end of the visible union
union() { // beginning of the cut union
translate([0, 0, ring_elevation])
cylinder(h=ring_height, d=cone_base);
}; // end of the cut union
}; // end of project difference
// inside column for the ring's center
cylinder(h=connector_height, d=cone_tip+2);
}; // end of rotate
// variables
$fn=360;
2 Likes
Here is a more complex part – an auger that I incorporated into a design I’m making. For complex models like this, I rely on finding these functions online.
// Parametric Printable Auger
// It is licensed under the Creative Commons - GNU GPL license.
// 2013 by William Gibson
// http://www.thingiverse.com/thing:96462
use <utils/build_plate.scad>
////////////
//Examples//
////////////
//Simple Example
// auger(r1=1/8*inch, r2=.75*inch, h=1*inch,
// turns=2, multiStart=1, flightThickness = 0.6,
// overhangAngle=20, supportThickness=0.0);
//Multistart example
// auger(r1=1/2*inch, r2=2*inch, h=2*inch,
// turns=1, multiStart=3, flightThickness = 0.6,
// overhangAngle=20, supportThickness=0.0);
//Support
// auger(r1=1/2*inch, r2=2*inch, h=2*inch,
// turns=2, multiStart=1, flightThickness = 0.6,
// overhangAngle=10, supportThickness=0.4);
//////////////////////
//CUSTOMIZER OPTIONS//
//////////////////////
/* [Auger] */
//The total amount of twist, in degrees
Auger_twist = 877; //[90:1080]
//The radius of the auger's "flight" past the shaft
Auger_flight_radius = 20; //[5:50]
//The number of "flights"
Auger_num_flights = 2; //[1:5]
//The height, from top to bottom of the "shaft"
Auger_flight_length = 100; //[10:200]
/* [Printer] */
//The overhang angle your printer is capable of
Printer_overhang_capability = 20; //[0:40]
//The thickness of perimeter support material
Auger_perimeter_thickness = 0.0; //[0:None, 0.8:Thin, 2:Thick]
/* [Uninteresting] */
//The radius of the auger's "shaft"
Auger_shaft_radius = 10; //[1:25]
//The thickness of the "flight" (in the direction of height)
Auger_flight_thickness = 1; //[0.2:Thin, 1:Medium, 10:Thick]
Auger_handedness = "right"; //["right":Right, "left":Left]
/* [Build plate] */
//for display only, doesn't contribute to final object
build_plate_selector = 3; //[0:Replicator 2,1: Replicator,2:Thingomatic,3:Manual]
//when Build Plate Selector is set to "manual" this controls the build plate x dimension
build_plate_manual_x = 200; //[100:400]
//when Build Plate Selector is set to "manual" this controls the build plate y dimension
build_plate_manual_y = 200; //[100:400]
build_plate(build_plate_selector,build_plate_manual_x,build_plate_manual_y);
/* [Hidden] */
M_PI = 3.14159;
mm = 1;
inch = 25.4 * mm;
auger(
r1 = Auger_shaft_radius,
r2 = Auger_shaft_radius + Auger_flight_radius,
h = Auger_flight_length,
overhangAngle = Printer_overhang_capability,
multiStart = Auger_num_flights,
flightThickness = Auger_flight_thickness,
turns = Auger_twist/360,
pitch=0,
supportThickness = Auger_perimeter_thickness,
handedness=Auger_handedness,
//$fn=50,
$fa=12,
$fs=5
);
//////////////////////
//Auger Library Code//
//////////////////////
//Notes:
//Specify 'pitch' OR 'turns' (pitch overrides turns)
//r1 >= 1mm please
//flightThickness >= extrusion thickness of your printer
//supportThickness >= 2 * extrusion width of your printer, or zero to turn off.
module auger(r1 = 0.5*inch, r2 = 0.75*inch, h=1*inch, multiStart=1,
turns=1, pitch=0,
flightThickness = 0.2*mm, overhangAngle=20, supportThickness=0*mm,
handedness="right" /*"left"*/)
{
assign(_turns = ((pitch>0?h/(pitch+flightThickness):turns)))
{
if(pitch != 0)
{
echo("Pitch defined - ignoring turns parameter");
//Each 1 turn is a height of (pitch+flightThickness)
//A height of h will make x turns where x = h / (pitch+flightThickness)
echo("Calculated turns = ", _turns);
}
else
{
if(turns < 0)
{
echo("ERROR: Cannot handle negative turns. Use handedness='left' instead to reverse rotation.");
}
}
assign(extraFlight = tan(overhangAngle)*(r2-r1))
{
difference()
{
auger_not_truncated(r1=r1, r2=r2, h=h, turns=_turns,
flightThickness=flightThickness, overhangAngle=overhangAngle,
multiStart=multiStart, supportThickness=supportThickness,
handedness=handedness=="right"?1:-1);
//Cut off bottom of auger so it's printable.
translate([0,0,-extraFlight])
cube([r2 * 3,r2 * 3,2*extraFlight], center=true);
}
}
}
}
module auger_not_truncated(r1 = 0.5*inch, r2 = 0.75*inch, h=1*inch, turns=1, flightThickness = 0.2*mm, overhangAngle=20, multiStart=1, supportThickness=0*mm, handedness=1)
{
assign(extraFlight = tan(overhangAngle)*(r2-r1))
{
if(supportThickness > 0)
{
difference()
{
cylinder(h=h, r=r2+0.1, $fs=0.5);
translate([0,0,-1])
cylinder(h=h+2, r=r2-supportThickness+0.1, $fs=0.5);
}
}
cylinder(r=r1, h=h,$fs=0.5); //Central shaft
for(start=[1:1:multiStart]) //render each flight
{
rotate([0,0,handedness*360*(start-1)/multiStart])
augerFlight(flightThickness=flightThickness, turns=turns, rHidden=(r1>6?r1-5:1), r1=r1, r2=r2, h=h, extraFlight=extraFlight, handedness=handedness);
}
}
}
module augerFlight(flightThickness, turns, rHidden, r1, r2, h, extraFlight, handedness)
{
if($fs < 0.1)
{
echo("WARNING: $fs too small - clamping to 0.1");
}
if($fa < 0.1)
{
echo("WARNING: $fa too small - clamping to 0.1");
}
//Calculate numSteps based on $fn, $fs, $fa
assign($fs = max(0.1, $fs), $fa = max(0.1, $fa),
numSteps=($fn > 0.0) ? $fn :
max(5,
max(h/(max($fs,0.1)),
max(360.0 * turns / $fa,
r2*2*M_PI*turns / max($fs,0.1)))))
{
echo("Number of Steps calculations:");
echo("minimum",5);
echo("height step", h/(max($fs,0.1)));
echo("angle", 360.0 * turns / $fa);
echo("perimeter size", r2*2*M_PI*turns / max($fs,0.1));
echo("numSteps = maximum: ", numSteps);
assign(heightStep=((h-(flightThickness))/numSteps))
{
translate([0,0,-extraFlight]) //Move down so the extraFlight material is below z=0
{
for(step=[0:1:numSteps-1]) //For each step in a flight
{
rotate([0,0,handedness*turns*step/numSteps*360])
translate([0,0,heightStep*step])
if(handedness==1)
augerPolyhedron(flightThickness=flightThickness, extraFlight=extraFlight, rHidden=rHidden, r1=r1, r2=r2, turns=turns, numSteps=numSteps, heightStep=heightStep);
else
mirror([1,0,0])
augerPolyhedron(flightThickness=flightThickness, extraFlight=extraFlight, rHidden=rHidden, r1=r1, r2=r2, turns=turns, numSteps=numSteps, heightStep=heightStep);
}
}
}
}
module augerPolyhedron(flightThickness, extraFlight, rHidden, r1, r2, turns, numSteps, heightStep)
{
//_1 is first angle, _2 is second angle
//_I is inside, _O is outside
assign(top_1_I=flightThickness+extraFlight, bot_1_I=0,
top_1_O=flightThickness+extraFlight, bot_1_O=extraFlight,
degOverlap=0.1,
rHiddenCorrection=(r1-rHidden)/(r2-r1)
)
{
//echo(rHidden, r1, r2);
//echo("rHiddenCorrection=",rHiddenCorrection);
//echo("rHiddenCorrection*extraFlight=",rHiddenCorrection*extraFlight);
//echo("heightStep=",heightStep);
polyhedron(
points=[
[0,rHidden,bot_1_I-rHiddenCorrection*extraFlight], //0
[0,rHidden,top_1_I], //1
[0,r2, bot_1_O], //2
[0,r2, top_1_O], //3
[-rHidden*sin(360*turns/numSteps+degOverlap), //4
rHidden*cos(360*turns/numSteps+degOverlap),
bot_1_I+heightStep-rHiddenCorrection*extraFlight], //+rHiddenCorrection*heightStep-rHiddenCorrection*extraFlight],
//
[-rHidden*sin(360*turns/numSteps+degOverlap), //5
rHidden*cos(360*turns/numSteps+degOverlap),
top_1_I+heightStep],
[-r2*sin(360*turns/numSteps+degOverlap), //6
r2*cos(360*turns/numSteps+degOverlap),
bot_1_O+heightStep],
[-r2*sin(360*turns/numSteps+degOverlap), //7
r2*cos(360*turns/numSteps+degOverlap),
top_1_O+heightStep]
],
triangles=[
[0,1,2], //"triangle" 1
[2,1,3],
[4,6,5], //"triangle" 2
[6,7,5],
[1,4,5],
[1,0,4], //Inner "square"
[3,7,6],
[3,6,2], //Outer "square"
[0,2,4],
[4,2,6], //Bottom "square"
[1,5,3],
[5,7,3], //Top "square"
]);
}
}
module augerPolyhedronBackup(flightThickness, extraFlight, r1, r2, turns, numSteps, heightStep)
{
//_1 is first angle, _2 is second angle
//_I is inside, _O is outside
assign(top_1_I=flightThickness+extraFlight, bot_1_I=0, top_1_O=flightThickness+extraFlight, bot_1_O=extraFlight, degOverlap=0.1)
{
polyhedron(
points=[
[0,r1,bot_1_I], //0
[0,r1,top_1_I], //1
[0,r2, bot_1_O], //2
[0,r2, top_1_O], //3
[-r1*sin(360*turns/numSteps+degOverlap), //4
r1*cos(360*turns/numSteps+degOverlap),
bot_1_I+heightStep],
[-r1*sin(360*turns/numSteps+degOverlap), //5
r1*cos(360*turns/numSteps+degOverlap),
top_1_I+heightStep],
[-r2*sin(360*turns/numSteps+degOverlap), //6
r2*cos(360*turns/numSteps+degOverlap),
bot_1_O+heightStep],
[-r2*sin(360*turns/numSteps+degOverlap), //7
r2*cos(360*turns/numSteps+degOverlap),
top_1_O+heightStep]
],
triangles=[
[0,1,2], //"triangle" 1
[2,1,3],
[4,6,5], //"triangle" 2
[6,7,5],
[1,4,5],
[1,0,4], //Inner "square"
[3,7,6],
[3,6,2], //Outer "square"
[0,2,4],
[4,2,6], //Bottom "square"
[1,5,3],
[5,7,3], //Top "square"
]);
}
}
}
2 Likes
Clean old configuration files from your Debian based system:
apt purge $(dpkg -l | awk '/^rc/ { print $2 }')
It is very useful after doing an in-place release upgrade. Though be careful and read the output before proceeding.
2 Likes
These are pretty cool and def above my head, Thank you!
Really cool. We need to move this to a dedicated SCAD thread.
watch
Execute a program periodically. Can be handy for working on scripts.
# Display date & time each second:
watch --no-title date
# Display output of a script every 0.5 seconds:
watch --interval 0.5 --no-title ./MY_PROJECT.sh
Usage:
watch [options] command
Options:
-b, --beep beep if command has a non-zero exit
-c, --color interpret ANSI color and style sequences
-d, --differences[=<permanent>]
highlight changes between updates
-e, --errexit exit if command has a non-zero exit
-g, --chgexit exit when output from command changes
-n, --interval <secs> seconds to wait between updates
-p, --precise attempt run command in precise intervals
-t, --no-title turn off header
-x, --exec pass command to exec instead of "sh -c"
-h, --help display this help and exit
-v, --version output version information and exit