Korn/ksh - calculate percentage? (poss awk?)

[Spud1]

Just a quick question,

I've come accross a problem while writing a shell script (korn). Basically we don't have korn93 on most of our servers, so can't use the built-in floating point math to do things like work out percentages.

That leaves me with finding another way - now from what I have found on the net I can use AWK to do this? Despite having done a fair bit of work with unix before I have not yet used AWK, and while i'm sure I should learn how to use it I don't have the time at the moment - so would anyone please be able to show me how to calculate a simple percentage using it?

I have the values stored as variables in my script already, just need to evaluate them to a percentage now =)

any help would be appreciated - a different solution or an explanation of how to use awk to do it would be great.

cheers

spud/pete


edit: oh and also - this needs to be a reasonably standard unix component that I use, not perl for example (it's not set up on some of our servers) That's part of the problem, given the choice the whole script would have been done in perl lol

[aidanjt]

echo "${var1}/${var2}*100" | bc -l

would something like that not do?..

[Spud1]

because korn doesn't support floating point arithmatic by default

Otherwise i could do as you suggest - but that only works for arithmatic.

Later versions of ksh support doing TYPESET -F <varname> to mark it as floating point, but otherwise it will only do integer arithmatic (ie no decimals)

btw in most unix OS's (this is Solaris 8) sh = ksh, if you look inside /bin/sh you just have a link to /bin/ksh =)

[Spud1]

well you edited your earlier post so my above reply doesn't make much sense anymore....

But BC looks like it would do the job, wonder if it's faster than awk or not tho Still looking for an awk way to do it if anyone has one so I can compare the two, but i'll try BC tomorrow at work ty,

[aidanjt]

well you edited your earlier post so my above reply doesn't make much sense anymore....

But BC looks like it would do the job, wonder if it's faster than awk or not tho Still looking for an awk way to do it if anyone has one so I can compare the two, but i'll try BC tomorrow at work ty,

Yea, I reread your first post after I posted cos I'm half asleep and I missed that part about floating point math... sorry :/

[b0redom]

How accurate do you need to be? Can't you multiply by 100 before generating the percent ie:

57/89

Instead of doing (57/89) *100

Try (57*100)/89

The result will be the same, but you're less likely to hit FP problems?

Alternativly, how about a little C++ program? If all you need to work out a percentage, you can take in 2 inputs and drop out a percent - assuming your architectures are consistant, you can deploy a little binary across everything?

Tom

[Spud1]

thanks aidanjt - BC seems to do the job nicely

b0redom - thanks for the suggestion but BC is built in to all of our servers, so it's simplest to use that

[aidanjt]

Most welcome, it's nice to see people making good use of shell scripts, even if it's yucky solaris that they have to work with