Is it bad practise to exit in function?

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11-27-2009

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Is it bad practise to exit in function?

Question is title, I don't understand why all examples I am reading return constants error values instead of just exiting under certain conditions... then back in main script test return value and exit if true, to me seems like a lot of extra typing and test conditions which can make for bulky and buggy code...
this is a test I just did, that shows you can exit from functions.... so I don't really understand what is wrong with the code below.

file: xxx

Code:

# function to exit
tstexit()
{
    echo "exiting now!"
    exit 1
}

file: zzz

Code:

#test for exit in function
. xxx
tstexit
echo "this is beyond the function will it echo?"
exit 0

output:

Code:

exiting now!

Last edited by gcampton; 11-27-2009 at 10:10 AM..

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It depends on your needs if you want to exit immediately from the function or want some processing of return codes 1st as kind of summary and central processing of these. I think that's totally up to you.

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See The Rule of Repair in the 'Art of Unix Programming' by Eric S Raymond

here:
Basics of the Unix Philosophy

jim mcnamara

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Quote:

Originally Posted by jim mcnamara

See The Rule of Repair in the 'Art of Unix Programming' by Eric S Raymond

here:
Basics of the Unix Philosophy

So going by that, I should be exiting in the function anyway rather than carrying on returning values back to main script to exit from there...

basically the examples have for instance, test on read/write file condition:
errors:

Code:

NOERROR=0
FILENOEXIST=1
FILENOREAD=3
FILELOCKED=9

readonly NOERROR FILENOEXIST FILENOREAD FILELOCKED

fnctns:

Code:

function chkread
{
    if [ ! -w $file ]
    then
        return $NOREAD
    fi
}

main script:

Code:

.fnctns

chkread
stat=$?

if [ "$stat" -eq "$NOREAD" ]
then
    echo "Unable to read/write, check permissions"
    echo  $usage
    exit 1
fi

seems a bit silly when you can have it just say in functions;

fnctns:

Code:

function chkread
{
    if [ ! -w $file ]
    then
        echo "Unable to read/write, check permissions"
        echo  $usage
        exit 1
    fi
}

main script:

Code:

.fnctns

chkread

Thanks for the link.

Last edited by gcampton; 11-27-2009 at 11:01 AM..

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IMO

ckread means: check to see if I can read a file

Code:

if [ ! -w $file ]

does not check to see if a file is readable or not.

jim mcnamara

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slip.... -r for read, -w for write, my script is testing just about every test possible, however when posting I was typing quick and only giving basic examples.

Last edited by gcampton; 11-27-2009 at 07:35 PM..

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