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From: | Linda Walsh |
Subject: | Re: status on $[arith] for eval arith vsl $((arith))?? |
Date: | Wed, 11 Apr 2012 22:01:12 -0700 |
User-agent: | Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.8.1.24) Gecko/20100228 Lightning/0.9 Thunderbird/2.0.0.24 Mnenhy/0.7.6.666 |
Greg Wooledge wrote:
On Wed, Apr 11, 2012 at 02:34:01AM -0700, Linda Walsh wrote:- for ((vl=$((v_level - 1)); $vl > 0; --vl))The inside of the for ((...)) is already a math context. You don't need another $((...)) inside it. for ((vl = v_level - 1; vl > 0; --vl)) Or is that another "irrelevant detail"?
Um... Why do you think I included it -- I NEVER saw anything like that where [] was used... people seem to not understand the (()) is arith, but you need $(()) to get the value out of the insides... But the examples of use of $(()) are leaning far more toward the perverse side than simple use of $[].. a few examples: - options="$(expr "${options}" : "\(.\{$((${last_option_index}-1))\}\)")" - YESTERDAY=$(date -r $((`date +%s` - 86400 )) +%d/%m/%Y - PREGAP=$(($(echo $OFFSETS | cut -f1 -d' '))) - for ((vl=$((v_level - 1)); $vl > 0; --vl)) --------------------- It's irrelevant to 'function', but not to efficiency or readability. But hey, gold star for paying attention! ;-) (those are all examples from various system scripts in /usr...
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