Is it possible to run two loops at the same time? - bash

Question

So I have a project in my cyber security class to make a bash game. I like to make one of those medieval games where you make farms and mines to get resources. Well I like to make something like that. To do that I have to have two while loops running. Like this
while [ blah ]; do
blah
done
while [ blah ]; do
blah
done
Is it possible to run two while loops at the same time and if I am writing it wrong how do I write it?

Answer 1

If you put a & after each done, like done&, you will create new processes in the background that run the while loops. You will have to be careful to realize what this means though, since the bash script will continue executing commands after creating those new processes even if they are not finished. You might use the wait command to prevent this from happening, but I'm not too used to using that so I cannot vouch for it.

Answer 2

Yes, but you will have to fork a new process for each while loop to be executing in. Technically, they won't both run at the same time (unless you consider multiple cores, but this isn't even garaunteed).
Below is a link to how to fork multiple processes using bash.
Forking / Multi-Threaded Processes | Bash
Since you mention this is a school project, I'll stop here lest I help you "not learn".
R

Answer 3

First things first, wrap the loop into a function and then fork it.
This is done when you want to split a process, for example, if I'm processing a CSV with 160,000+ lines, single process/"thread" will take hours. If you wrap the loop into a function and simply fork it, you will have x amount of processes running, then add wait/kill defunct process loop and you are done. here what you are looking at.
while loop with nested loop:
function jobA() {
while read STR;
do
touch $1_temp
key=$(IFS="|";set -- $STR; echo $1)
for each in ${blah[#]};
do
#echo "$each"
done
done <$1;
}
for i in ${blah[#]};
do
echo "$i"
$(jobRDtemp $i) &
child_pid=$!
parent_pid=$$
PIDS+=($child_pid)
echo "forked process $child_pid with parent $parent_pid"
done
for pid in ${PIDS[#]};
do
wait $pid
done
echo "all jobs done"
sleep 1
Now this is wrapped, here is example of a FORKED loop. this means you will have parallel processes run in the background, WAIT will wait for ALL to complete before proceeding. This is important for some type of scripts.
Also, DO NOT use nested FOR loops written C style like presented above, example:
for (( i = 1; i <= 5; i++ )) ### Outer for loop ###
This is VERY slow. use THIS type:
for each in ${blah[#]};
do
#echo "$each"
if [ "$key" = "$each" ]; then
# echo "less than $keyValNeed..."
echo $STR >> $1_temp
fi
done

Answer 4

You could also use nested for loops
for (( i = 1; i <= 5; i++ )) ### Outer for loop ###
do
for (( j = 1 ; j <= 5; j++ )) ### Inner for loop ###
do
echo -n "$i "
done
echo "" #### print the new line ###
done
EDIT: I thought you meant Nested Loop but reading again you said running both loops "at the same time". I will leave my answer here though.