pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perlbrew use perl-5.8.9 A sub-shell is launched with perl-5.8.9 as the activated perl. Run 'exit' to finish it. pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl pos2.pl F1.DAT int2 2147483648 int4 4294967296 int8 8589934592 int16 17179869184 File F1.DAT cached 1073741824 bytes in 9 seconds @ 119304647.111111 bs pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl pos2.pl F1.DAT P@2 int2 2147483648 int4 4294967296 int8 8589934592 int16G17179869184 File F2.DAT cached -2147483648 bytes in 18 seconds @ -119304647.111111 bs pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ exit exit pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perlbrew use perl-5.10.1 A sub-shell is launched with perl-5.10.1 as the activated perl. Run 'exit' to finish it. pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl pos2.pl F2.DAT 1 int2 2147483648 int4 4294967296 int8 8589934592 int16 17179869184 File F1.DAT cached 1073741824 bytes in 8 seconds @ 134217728 bs pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl pos2.pl F1.DAT P@2 int2 2147483648 int4 4294967296 int8 8589934592 int16 17179869184 File F2.DAT cached -2147483648 bytes in 18 seconds @ -119304647.111111 bs pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ exit exit pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl -v This is perl 5, version 20, subversion 2 (v5.20.2) built for i586-linux-gnu-thread-multi-64int (with 51 registered patches, see perl -V for more detail) Copyright 1987-2015, Larry Wall Perl may be copied only under the terms of either the Artistic License or the GNU General Public License, which may be found in the Perl 5 source kit. Complete documentation for Perl, including FAQ lists, should be found on this system using "man perl" or "perldoc perl". If you have access to the Internet, point your browser at http://www.perl.org/, the Perl Home Page. pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl pos2.pl F1.DAT int2 2147483648 int4 4294967296 int8 8589934592 int16 17179869184 File F1.DAT cached 1073741824 bytes in 8 seconds @ 134217728 bs pme@pme-notebook: ~/Develop/workpme@pme-notebook:~/Develop/work$ perl pos2.pl F1.DAT P@2 int2 2147483648 int4 4294967296 int8 8589934592 int16 17179869184 File F2.DAT cached 2147483648 bytes in 17 seconds @ 126322567.529412 bs