#!/usr/bin/perl -w
use strict;
use Getopt::Long;

my $VAR        = 'PATH';
my $OFFSET     = 0;
my $LENGTH     = 0;
my $EXECUTABLE = '';
my $EVAL       = 1;

my @LIST;

GetOptions(
    '-variable=s'   => \$VAR,
    '-offset=i'     => \$OFFSET,
    '-length=i'     => \$LENGTH,
    '-executable=s' => \$EXECUTABLE,
    '-bashsource!'  => \$EVAL,
);

exit(1) unless $ENV{$VAR};

my @P = split ':', $ENV{$VAR};
local $" = ':';
if ($EXECUTABLE) {
    @LIST = `$EXECUTABLE`;
    chomp @LIST;
}
else {
    @LIST = @ARGV;
}
splice @P, $OFFSET, $LENGTH, @LIST;
if ($EVAL) {
    print "$VAR=@P;export $VAR";
}
else {
    print "@P";
}

__END__

=head1 NAME

splicepath - Returns a string with the spliced PATH

=head1 SYNOPSIS

  $ eval `splicepath -v PERL5LIB -o 0 -l 1 ~/src/perl/Parse-Eyapp-1.113/lib`

=head1 DESCRIPTION

Works like Perl splice but with environment variables that follow
the C<:> separation convention (like C<PATH> or C<PERL5LIB>)

The mening of the options are as follows:

=over 2

=item *  C<-variable>

The environment variable (by default C<PATH>)

=item * C<-offset #number>

The offset. Like in Perl C<splice>

=item * C<-length #number>

The length. Like in Perl C<splice>

=item * C<-executable scriptname>

The script C<scriptname> will be executed and
the lines of its output  inserted in the variable

=item *  C<-bashsource>

True by default. The output is bash source to set the environment
variable

=back

=head1 EXAMPLES

Assuming the path:

  $ echo $PATH
  .:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

The command

  $ splicepath -o 2 -l 1 ~/bin

produces the output:

  PATH=.:/usr/local/sbin:/home/username/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games;export PATH