run commands in parallel

[Lobster]

In this prog, the music plays then when it stops
the image is displayed
How to run at the same time?

Code: Select all

#! /bin/bash
madplay ivy.mp3 "$@"
xcowsay --cow=Lobster6 --time=1 --dream=puppylogo96.png "$@"

Sure I have asked this before - can not find reply

[ken geometrics]

In this prog, the music plays then when it stops
the image is displayed
How to run at the same time?

Code: Select all

#! /bin/bash
madplay ivy.mp3 "$@"
xcowsay --cow=Lobster6 --time=1 --dream=puppylogo96.png "$@"

Sure I have asked this before - can not find reply

Many things will run in multiple tasks if you put the "&" on the end of the line.

Try:

Code: Select all

madplay ivy.mp3 "$@" &
xcowsay --cow=Lobster6 --time=1 --dream=puppylogo96.png "$@" &

echo "And this too"

[Lobster]

Thanks ken geometrics,

I will just put on my dunce hat
and go stand in the corner . . .

[Pizzasgood]

As mentioned, sticking an ampersand on the end of a command will background it, so that it runs in parallel. However, what if you have a group of commands that should execute sequentially, but you want the group to run in parallel to the rest of the script? Well, you could put it into a function and run the function in parallel. Another option is to put it into a subshell by wrapping it in parenthesis, and then stick an ampersand after the closing paren.

The following is an example of that. It has a block of code at the top that will run in parallel to the rest of the code. That first part just opens four terminals.

The second part of the code, which will run at the same time as the first part (indeed, it will probably finish first), draws a picture in your terminal. For best results, use a terminal with a black background. With most terminals, that can be achieved by running them with the the -bg black -fg white options.

I got a bit carried away on that second part

Code: Select all

#!/bin/sh
#This opens several terminals, one per second.  At the same time, a
#Different set of code gradually draws an image on the screen.

#Create the files
(
        #try to find a terminal
        for i in xterm rxvt urxvt sakura; do
                which $i >/dev/null && terminal=$i
        done
        for i in {0..3}; do
                urxvt &
                sleep 1
        done
) &

########################################################################

#This part does the drawing of cool things.
#Note:  If you want to use this independently of this example, just cut
#everything below the following line.  All the above is irrelevant.
###--------- CUT AFTER THIS --------------------------------------------
#!/bin/sh
#Draws a pretty picture

#This looks best in a terminal with a black background.  For example:
#    rxvt -bg black -fg white

h=12
tw=4 #even for alignment
th=3
#increasing this dehances the chrome factor
scarcity=9

###################################################
#define a bunch of colors
#the capitalized versions are "bold" or "bright"

 black='\033[0;30m'
 BLACK='\033[1;30m'
 white='\033[0;37m'
 WHITE='\033[1;37m'

   red='\033[0;31m'
   RED='\033[1;31m'
 green='\033[0;32m'
 GREEN='\033[1;32m'
yellow='\033[0;33m'
YELLOW='\033[1;33m'
  blue='\033[0;34m'
  BLUE='\033[1;34m'
purple='\033[0;35m'
PURPLE='\033[1;35m'
  cyan='\033[0;36m'
  CYAN='\033[1;36m'

    NC='\033[0m'
  grey=$BLACK
###################################################

char1="${green}/${NC}"
char2="${green}^${NC}"
char3="${green}\\\\${NC}"
chart1="${yellow}|${NC}"
chart2="${yellow}=${NC}"
chart3="${yellow}|${NC}"

function draw_bulb(){
        char="*"
        color_pool=($RED $YELLOW $BLUE $CYAN $PURPLE)
        let "index=RANDOM%${#color_pool[@]}"
        echo "${color_pool[$index]}${char}${NC}"
}

function draw_item(){
        boring="$1"
        let 'decision=RANDOM%scarcity'
        if [ $decision -eq 0 ]; then
                draw_bulb
        else
                echo "$boring"
        fi
}

let 'w=h*2'

let 'cx=w/2'
let 'cy=h/2'

for x in $(seq 0 $cx); do
        line_start="${line_start} "
done
echo -e "${line_start}${WHITE} _A_ ${NC}"
echo -e "${line_start}${WHITE} /^\ ${NC}"

for y in $(seq 1 $h); do
        let 'x1=cx-y+1'
        let 'x2=cx+y-1'
        line=''
        for x in $(seq 0 $x1); do
                line="${line} "
        done
        line="${line} $(draw_item "$char1")"
        let 'start=x1+1'
        let 'end=x2-1'
        for x in $(seq $start 2 $end); do
                line="${line} $(draw_item "$char2")"
                #line="${line} ${char2}"
        done
        line="${line} $(draw_item "$char3")"
        echo -e "$line"
        let 'y++'
done
for y in $(seq 1 $th); do
        let 'x1=cx-tw/2'
        line=''
        for x in $(seq 0 $x1); do
                line="${line} "
        done
        line="${line} ${chart1}"
        let 'start=x1+1'
        let 'end=x1+tw'
        for x in $(seq $start 2 $end); do
                line="${line} ${chart2}"
        done
        line="${line} ${chart3}"
        echo -e "$line"
done

[Iguleder]

There's another method, in plain C. It was originally written for my own distro to speed up init so it starts things in parallel ... works great

Code: Select all

//dr 0.1 by Iguleder

// To compile:
// gcc -lpthread -o dr dr.c

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

void *runThread(void *command)
{

  system(command);

}

int main(int argc, char** argv) {
    
  pthread_t commandThreads[argc-1];
  long i;

  for(i=1; i<=argc-1; i++)
  {

    pthread_create(&commandThreads[i-1], NULL, runThread, (void *)argv[i]);
      
  }

  pthread_exit(NULL);

}

To use it: compile, put in /usr/bin, then do "dr <command 1> <command 2> <command 3> [ ... ]".

In your case:
dr "madplay ivy.mp3 $@" "xcowsay --cow=Lobster6 --time=1 --dream=puppylogo96.png $@"

[potong]

Xargs has a -P n option which will run maximum number of n jobs at a time or use -P 0 to run all ( I don't think this option is available on BusyBox).

GNU parallel is more fancy and can do all manner of clever things on single/multiple processor machine(s) see here for a screen cast
and here for the home page

HTH

Potong