How to create a bash script in Linux that does multiple tasks at once

Question

I would like to create a bash script that would contain the following:

I/O redirection
Pipes
Symbolic Link
Wild cards
Add a user to multiple groups.

I know how to execute the commands to create each of them individually, but I can't figure it out how I could create a bash script that would execute all of them at once. Can someone help me please? I would greatly appreciate it.

    #/bin/bash

    cd /home

    mkdir testdir &&

    cd testdir

    touch testfile.txt | ln -s /etc/passwd symboliclink && cd .. | mkdir things && cp -rf /testdir /things | usermod -aG admins,hr,payroll test

Jameson · Accepted Answer · 2017-03-19 18:58:59Z

3

Put each thing you want to do in a function, and then background the execution of each:

do_redirection_stuff() {
    # your stuff here
}

do_wild_card_stuff() {
    # your stuff here
}

do_symbolic_link_stuff() {
    # kool stuff
}

do_parallel_tasks() {
    do_redirection_stuff &
    do_wild_card_stuff &
    do_symbolic_link_stuff &

    wait # For all of them to finish
}

do_parallel_tasks

Update (code was added to OP's question)

It seems like you're confused about how shell redirection is used. In the code you provided, you should just serially execute each command. Likewise, none of these commands are likely to block for very long, so executing them in parallel is overkill.

#!/bin/bash
cd /home
mkdir testdir
cd testdir
touch testfile.txt
ln -s /etc/passwd symboliclink
cd ..
mkdir things
cp -rf /testdir /things
usermod -aG admins,hr,payroll test

edited Mar 19, 2017 at 18:58

answered Mar 18, 2017 at 1:56

Jameson

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4 Comments

shabam Over a year ago

Jameson, thank you for your example. But I'm still having difficulties to understand the whole process! Would it be there an easier approach to accomplish this task?

Jameson Over a year ago

@shabam you should post the code you have so far so there can be a concrete discussion.

shabam Over a year ago

I have added to my question what I did so far. Your help is very much appreciated.

shabam Over a year ago

At the end of the script I was trying to create an alias. So,what I did is: echo "alieas test='cd && ./myscript.sh'" >> ~/.bashrc . ~/.bashrc It does add the line to the .bashrc but it seems that the . ~/.bashrc it's not working. Can you please help. I don't know what I'm doing wrong!

Cris Luengo · Accepted Answer · 2017-03-18 02:00:40Z

0

I learned about a tool yesterday called parallel: https://www.gnu.org/software/parallel/

It makes it really easy to run any number of tasks in parallel, and sorts their output too. Take some time to look through the tutorial, it'll be time well spent!

answered Mar 18, 2017 at 2:00

Cris Luengo

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