Re: Bypassing variable substitution

Rajan wrote:

> This does work. If the string has as string has something like $item
shell
> is trying to expand it. Since I am double quoting it. If I single quote
> it, the single quotes inside of the string are causing a problem.

$ ex****t var="value"
$ awk 'BEGIN {system("echo \"$var\"")}'
value
$ awk -v sq="'" 'BEGIN {system("echo "sq"$var"sq)}'
$var

Where are you getting errors? Post some example.

> Let us make this more simple and generic.  The question is can I run a
> command with arguments containing $HOME , single quote and *s without a
> lot of hopping in and out of  quotes. Something like the system in perl
> (http://perldoc.perl.org/functions/system.html)
which when multiple
> arguments are passed sends all the strings as is to the first element
> without passing them through the shell?  To be more generic, does system
> command always pass the command through the shell or is there a way the
> command can be invoked directly without shell looking at its arguments?
> Any information would help.

AFAIK system() should invoke sh -c <command>, so the shell interprets the
arguments.

-- 
All the commands are tested with bash and GNU tools, so they may use
nonstandard features. I try to mention when something is nonstandard (if
I'm aware of that), but I may miss something. Corrections are welcome.