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Full Discussion: Correct bash substitution
Top Forums Shell Programming and Scripting Correct bash substitution Post 302449095 by teresaejunior on Saturday 28th of August 2010 01:00:14 PM
Old 08-28-2010
Correct bash substitution
Hello!

I'm writing a shell script using #!/bin/bash instead of #!/bin/sh because of the substitution: ${!variable}, which won't work with sh. My main problem is the following (just a summarized example, the script is much more complex):

Code:
# sourced from a configuration file, we have a lot of options
opt_1="My file"
opt_2="My option"
opt_3="My variable..."

# then we use a gui to request the new value, which will return:
form="New File Name|option 2|option 3"

x=1
printf "$form\n" | sed 's/|/\n/g' | while read option; do
    export opt_$x="$option" # we use export, which works with other scripts
    x=$((x+1))
done

for number in $(seq 1 3); do
    opt=opt_$number
    echo "$opt=${!opt}" # ${!opt} returns the old value, not the new exported!
done

Thank you!

---------- Post updated at 02:00 PM ---------- Previous update was at 12:32 PM ----------

At least someone to tell me the POSIX alternative for ${!variable}, please:

Code:
$ value=hello
$ greeting=value
$ echo $greeting
value
$ echo ${!greeting}
hello

Last edited by teresaejunior; 08-28-2010 at 02:12 PM.. Reason: You could paste this now in a terminal
 

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LEARN ABOUT SUSE

tk::optionmenu

Optionmenu(3)						User Contributed Perl Documentation					     Optionmenu(3)

NAME

       Tk::Optionmenu - Let the user select one of some predefined options values

SYNOPSIS

	   use Tk::Optionmenu;

	   $opt = $w->Optionmenu(
			       -options => REFERENCE_to_OPTIONLIST,
			       -command => CALLBACK,
			       -variable => SCALAR_REF,
			       );

	   $opt->addOptions( OPTIONLIST );

	   # OPTION LIST is
	   #   a)  $val1, $val2, $val3,...
	   #   b)  [ $lab1=>$val1], [$lab2=>val2], ... ]
	   #   c)  combination of a) and b), e.g.,
	   #	   val1, [$lab2=>val2], val3, val4, [...], ...

DESCRIPTION

       The Optionmenu widget allows the user chose between a given set of options.

       If the user should be able to change the available option have a look at Tk::BrowseEntry.

OPTIONS

       -options
	   (Re)sets the list of options presented.

       -command
	   Defines the callback that is invokes when a new option is selected.

       -variable
	   Reference to a scalar that contains the current value of the selected option.

       -textvariable
	   Reference to a scalar that contains the text label of the current value of the selected option.

METHODS

       addOptions
	   Adds OPTION_LIST to the already available options.

EXAMPLE

	use Tk;
	my $mw = MainWindow->new();

	my ($var, $tvar);
	my $opt = $mw->Optionmenu(
	       -options => [[jan=>1], [feb=>2], [mar=>3], [apr=>4]],
	       -command => sub { print "got: ", shift, "
" },
	       -variable => $var,
	       -textvariable => $tvar
	      )->pack;

	$opt->addOptions([may=>5],[jun=>6],[jul=>7],[aug=>8]);

	my $f = $mw->Frame(-relief=>'groove', -borderwidth => 2)->pack;
	$f->Label(-textvariable=>$tvar)->pack(-side => 'left');
	$f->Label(-text => " -> ")->pack(-side => 'left');
	$f->Label(-textvariable=>$var)->pack(-side => 'left');

	$mw->Button(-text=>'Exit', -command=>sub{$mw->destroy})->pack;

	MainLoop;

SEE ALSO

       Tk::Menubutton, Tk::BrowseEntry

perl v5.12.1							    2007-05-05							     Optionmenu(3)
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