Is `return` within function a compulsory requirement?

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?

1 Answer

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(){ ps -ef | grep -w "$1" | 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

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