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Article #1081

Re: bourne shell query

#1081
From: Scott Yelich
Date: Thu, 06 Sep 1990 16:08
39 lines
2119 bytes
>cwns1$ foo -r -r
>test: too many arguments
>cwns1$ foo -r
>[: argument expected
> >4) eval ${1:+'echo "Yup!"'}

Right, if I am at all worried about a variable evr starting with a dash,
I do something as ugly as:
test "${var:+:}"

See, most ALL of my internal variables I SET and they will never be -something.
And if they ever get to be -something then the value is invalid.

>This *is* a nice way to test whether or not a variable is set.
I use it for cases when there MIGHT be a -something.

For instance, I have special routines which parse command line options.

>  Nobody seems to consider the case statement, which avoids these problems:
>	   "$2")	return 0
>	   *)	return 1

Yeah, perhaps test should just be smarter, but we can't wait for that.

>>Now, does anyone have and BOURNE SHELL (ie: /bin/sh) routines to do math?
>Well, the shell running as /bin/sh on my machine is bash, and it has
>$[] to do arithmetic substitution.

I am looking for ART styles here... not shell substitutions!  Arrraugh!

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 Scott D. Yelich                         scott@[xanth.]cs.odu.edu [128.82.8.1]
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!abcfd20.larc.nasa.gov!tab00.larc.nasa.gov!scott
From: scott@tab00.larc.nasa.gov (Scott Yelich)
Newsgroups: comp.unix.shell
Subject: Re: bourne shell query
Message-ID: <SCOTT.90Sep6120809@tab00.larc.nasa.gov>
Date: 6 Sep 90 16:08:09 GMT
References: <75@iconsys> <925@hls0.hls.oz>
 <SCOTT.90Sep5124415@tab29.larc.nasa.gov>
 <1990Sep6.141133.3391@usenet.ins.cwru.edu>
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In-Reply-To: chet@cwns1.CWRU.EDU's message of 6 Sep 90 14:11:33 GMT