Gfilui

The the simpler form of a function is:

name () commands return 

I find no difference in a function with and without return.

Suppose the minimal code:

step_forward ()
 echo "step one;"
 return

turn_around() 
 echo "turn around."
 return


step_forward
turn_around

Run and check the exit status:

$ bash testing.sh
step one;
turn around.
$ echo $?
0

Run it again after commenting out return

$ bash testing.sh
step one;
turn around.
$ echo $?
0

In what circumstances should a function end with a return?

A return value is not required in a function. Normally a return would be used in a script for an exit value to be returned. Exit values are normally like a 1 or a 0 where a lot of scripters might use it for a 0 as successful and a 1 as not successful.

#!/bin/bash
#The following function returns a value of 0 or 1
function if_running() grep -v grep > /dev/null
 if [[ $? == 0 ]]; then
 return 0
 else
 return 1
 fi


#Read in name of a running process
read -p "Enter a name of a process: "

#Send REPLY to function
if_running $REPLY

#Check return value and echo appropriately
if [[ $? == 0 ]]; then
 echo "Return value is $?"
 echo "$REPLY is running..."
else
 echo "Return value is $?"
 echo "$REPLY is not running..."
fi

Examples:

~$ ./ps_test.bsh 
Enter a name of a process: ls
Return value is 1
ls is not running...

~$ ./ps_test.bsh 
Enter a name of a process: bash
Return value is 0
bash is running...

And this answer I wrote a little bit ago does not have return values but still gives output https://askubuntu.com/a/1023493/231142

#!/bin/bash
function area()
 circ=$(echo "3.14 * $1^2" 

#Read in radius
read -p "Enter a radius: "

#Send REPLY to function
area $REPLY

#Print output
echo "Area of a circle is $circ"

Example:

terrance@terrance-ubuntu:~$ ./circ.bsh 
Enter a radius: 6
Area of a circle is 113.04

Hope this helps!