[SOLVED] bash functions

Valkyrie_of_valhalla · 05-03-2010, 01:40 AM

I am trying to get pretty much the same thing as a:
du -bc | grep total | cut -f1

but using a recursive function in bash (learning exercise).

Trying to figure out what I did wrong.

Here is what I've written:

Code:

#!/bin/bash

#du -bc | grep total | cut -f1

function calcul
{
#    echo $1
    local sum=0

    sum=$(($sum+$(ls -l $1 | cut -d" " -f5)))

    cd $1
    
    for f in $( ls -1 ) ; do                    
        if [ -f $f ] ; then                    
             sum=$(($sum+$(ls -l $f | cut -d" " -f5)))
    
#            echo $f
#            echo $sum
        else
            sum=$(($sum+$(ls -l $f | cut -d" " -f5)))
            calcul $f
            sumrec=$?
            sum=$(($sum+$sumrec))
        fi
    done

    cd ..
    echo $sum
    return $sum
    
}

calcul .
sumfinal=$?
echo $sumfinal

The output of this script is:

Quote:

4
4106
9273
57

Aka, when returning from the function, it does not display the correct value...

I can't seem to figure out what I did wrong... any suggestions are welcomed.

catkin · 05-03-2010, 04:39 AM

The return command is limited to 255 as this command prompt session demonstrates

Code:

c@CW8:~$ function fun {
> return $1
> }
c@CW8:~$ fun 255; echo $?
255
c@CW8:~$ fun 256; echo $?
0

H_TeXMeX_H · 05-03-2010, 08:44 AM

Some recommendations:

What if you encounter a symlink ? You probably should take that into account because you could go into infinite recursion.

I would use 'stat -c %s' to determine file size not 'ls'.

Don't use return, just have a variable that holds the total and add it the total.

It's neater if you do 'let sum+=sumrec'.

I hate recursion, I recommend you don't use it in real life unless you have no other choice.

Valkyrie_of_valhalla · 05-03-2010, 09:03 AM

Thank you both for your replies.

I understand now, and I fixed it by doing an echo $sum instead of return $sum, and recalling the function by sum=$(($sum+$(calcul $f))).

And yes, I know it is bad practice... I would just use du, but unfortunately this was my task... thankfully solved now, and I fully understood my error

grail · 05-03-2010, 09:41 AM

Don't forget to mark the thread as SOLVED

tuxdev · 05-03-2010, 12:12 PM

What are you *really* trying to do? I have a strong suspicion that this could be done trivially and far more robustly with "find".