Thanks to everybody for your help and explainations. I ended up with what
I needed and an explaination of how somethings work. I also have a
direction on where to learn more
thanks again
david
On Wed, 11 Dec 2002, Robert P. J. Day wrote:
> On Wed, 11 Dec 2002, dbrett wrote:
>
> > Now I am really confused!
> >
> > This works:
> > #!/bin/bash
> >
> > if [ -z $1 ]; then
> > echo ''
> > echo "format is $0 'math equation'"
> > echo "i.e. $0 (2+2)*3"
> > echo ''
> > exit
> > fi
> >
> > echo $1 | /usr/bin/bc -l
>
> assuming that all you're doing is asking a shell script to run
> "bc" for you, here's a possible solution:
>
> -------------
>
> #!/bin/bash
>
> function usage {
> cat <<-EOF
> Usage: $0 equation.
> Aborting now.
> exit
> EOF
> }
>
> [[ $# -eq 1 ]] || usage
>
> echo $1 | /usr/bin/bc -l 2> /dev/null
>
> -------------
>
> notes:
>
> 1) the usage() function keeps that stuff out of the way, so you can call
> it more than once
>
> 2) [[ $# -eq 1 ]] is the recognized way to test the number of
> parameters
>
>
> and if all you're doing is simple arithmetic, this is already
> built into bash with the $(( )) construct, as in:
>
> $ echo $(((2+3)*10))
> 50
>
> using this built-in construct, you need not worry about whitespace
> since the construct is an inherent part of the shell.
>
> rday
>
>
>
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