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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