Very Computer

Hi All,

In the short example below, I've tried various quotes and
escapes with no luck.  Is this impossible, or am I
just tired???  I want to put a command inside a variable,
but the command references a variable thaty is not
yet defined.  Boy am I rusty on this stuff!

Any info is appreciated...
-Lou V.

#!/bin/ksh

##########################################################
# Is it possible to store a command in a variable, with
# an embedded variable in that command and assign a value
# to the embedded variable LATER, and then execute the
# command?
#
# I want the 'for loop' to literally translate to:
#
#      for item in `grep cookies /some/file | cut -d: -f1`
#
##########################################################

command="grep $string /some/file | cut -d: -f1"

# Set $string value  a bit later...

string=cookies

for item in `$command`
do
    echo $item is the first field in a line that has cookies.
done

Since you put the string in double quotes, the variable is expanded at
the time of the assignment.

If you want it to be expanded later, you must use single quotes in the
assignment, and use the "eval" command when you execute it.

Quote:

> #!/bin/ksh

> ##########################################################
> # Is it possible to store a command in a variable, with
> # an embedded variable in that command and assign a value
> # to the embedded variable LATER, and then execute the
> # command?
> #
> # I want the 'for loop' to literally translate to:
> #
> #      for item in `grep cookies /some/file | cut -d: -f1`
> #
> ##########################################################

> command="grep $string /some/file | cut -d: -f1"

> # Set $string value  a bit later...

> string=cookies

> for item in `$command`
> do
>     echo $item is the first field in a line that has cookies.
> done

--

Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Thanks, Barry.  I would have gotten the quoting right eventually if I
had thought about eval.  I was presuming the shell could handle this
directly.

Cheers,
Lou