Re: bash script problems

[Chris F.A. Johnson]

On Thu, 12 May 2005, Tony Jo wrote:

> "Chris F.A. Johnson" <cfajohnson@rogers.com> wrote in message
> news:mailman.4693.1115841231.2819.bug-bash@gnu.org...
> >     When quoting parts of a script or error messages, please be
> >     accurate (cut and paste rather than retyping). You used:
> >
> > temp=`expr $val1 + $val2`
> >
> >     or you wouldn't have received that error. The line you have would
> >     have assigned the literal value to $temp.
>
> Oh those were meant to be single quotes.
> temp='expr $val1 + $val2'

    You had single quotes in your post. They should be backticks.

> >     What are the values of $val1 and $val2? Use this command to see
> >     them:
> >
> > printf ":%s:%s:\n" "$val1" "$val2"
> >
> >     What is the result of:
> >
> > echo $(( $val1 + $val2 ))
> >
> >     What command did you use to fill those variables?
>
> Those lines didn't seem to print out anything unforunately

    Impossible.

    The first command would have printed, at the very least, ":::".

    The second would either have printed a number or an error message.

> It prints out values when I simply type the variable name though.
> The variable holds the following:
> val1='cut -c8-9 usrTime'
> val2='cut -c7-8 sysTime'

    If those were the values, then the first command would have
    printed:

:cut -c8-9 usrTime;cut -c7-8 sysTime:

    What you presumably wanted was for those variables to hold the
    results of the commands, not the commands themselves. For that,
    you enclose the command in backticks, not single quotes:

val1=`cut -c8-9 usrTime`
val2=`cut -c7-8 sysTime`

    Or:

val1=$(cut -c8-9 usrTime)
val2=$(cut -c7-8 sysTime)


--
    Chris F.A. Johnson                     <http://cfaj.freeshell.org>
    ==================================================================
    Shell Scripting Recipes: A Problem-Solution Approach, 2005, Apress
    <http://www.torfree.net/~chris/books/ssr.html>