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Re: bash null conditional



Words by Craig White [Mon, Mar 30, 2009 at 11:41:11AM -0700]:
> On Mon, 2009-03-30 at 11:33 -0700, Agile Aspect wrote:
> > Craig White wrote:
> > > I'm in my bash book and looking on web but can't seem to resolve this
> > > simple problem.
> > >
> > > $ if [ -n "grep A121 myfile.csv" ]; then echo "null"; fi
> > > null
> > >
> > > $ if [ -n "grep A125 myfile.csv" ]; then echo "null"; fi
> > > null
> > >
> > > A125 definitely is null when I just run the grep command in the quotes
> > > but A121 definitely is not null.
> > >
> > > What am I missing on the if/null operator here?
> > >
> > > Craig
> > >
> > >   
> > I believe it's
> > 
> >     if [ -z "grep A121 myfile.csv" ]; then echo "null"; fi
> ----
> not working for me...
> 
> $ if [ -z "grep A121 ARdebtorsmaster.csv" ]; then echo "null"; fi
> $ if [ -z "grep A125 ARdebtorsmaster.csv" ]; then echo "null"; fi

No, 

if [ -z "`grep A121 ARdebtorsmaster.csv`" ]; then echo "null"; fi
if [ -z "`grep A125 ARdebtorsmaster.csv`" ]; then echo "null"; fi

or

[ -z "`grep A121 ARdebtorsmaster.csv`" ] && echo "null"
[ -z "`grep A125 ARdebtorsmaster.csv`" ] && echo "null"

-- 
Jose Celestino | http://japc.uncovering.org/files/japc-pgpkey.asc
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"One man’s theology is another man’s belly laugh." -- Robert A. Heinlein


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