Technology Tales

Adventures & experiences in contemporary technology

On numeric for loops in Korn shell scripting

18th October 2007

The time hounoured syntax for a for loop in a UNIX script is what you see below and that is what works with the default shell in Sun’s Solaris UNIX operating system, ksh88.

for i in 1 2 3 4 5 6 7 8 9 10
do
        if [[ -d dir$i ]]
        then
            :
        else
            mkdir dir$i
        fi
done

There is a much nicer syntax supported syntax the advent of ksh93. It follows C language conventions found in all sorts of places like Java, Perl, PHP and so on. Here is an example:

for (( i=1; i<11; i++ ))
do
        if [[ -d dir$i ]]
        then
            :
        else
            mkdir dir$i
       fi
done

Add a Comment

Your email address will not be published. Required fields are marked *

Please be aware that comment moderation is enabled and may delay the appearance of your contribution.

  • All the views that you find expressed on here in postings and articles are mine alone and not those of any organisation with which I have any association, through work or otherwise. As regards editorial policy, whatever appears here is entirely of my own choice and not that of any other person or organisation.

  • Please note that everything you find here is copyrighted material. The content may be available to read without charge and without advertising but it is not to be reproduced without attribution. As it happens, a number of the images are sourced from stock libraries like iStockPhoto so they certainly are not for abstraction.

  • With regards to any comments left on the site, I expect them to be civil in tone of voice and reserve the right to reject any that are either inappropriate or irrelevant. Comment review is subject to automated processing as well as manual inspection but whatever is said is the sole responsibility of the individual contributor.