system function not handling string properly

hermes1908 has asked for the wisdom of the Perl Monks concerning the following question:

Hey guys, I am trying to run a system command on a string extracted from an sql database. The string appears to be extracted correctly (it prints fine), however whenever I try an run an external program on it (using system), the program only receives the first character. I have posted the code I am using below.

#!/usr/bin/env perl

use strict;
use warnings;
use DBI;

my $file="sample";
my $dbh=DBI->connect("dbi:SQLite:dbname=$file","","") or die "Unable t
+o establish connection to $file\n";

my ($link)=$dbh->selectrow_array("SELECT value FROM ItemTable WHERE ke
+y='link'");

print "\$link is $link\n";
system("echo", $link);
$dbh->disconnect;
[download]

A sample sql file can be found at http://qpls.devio.us/sample Any help would be much appreciated,

Thanks,
Hermes

Comment on system function not handling string properly Download Code

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Re: system function not handling string properly by choroba (Cardinal) on Sep 06, 2013 at 21:02 UTC
Can you show what `$link` contains? It seems to work pretty well with `echo`, the only problem on my system is if `$link` is one of `-n`, `-e`, `-E`, or their combination (e.g.`-eEn`), which are interpreted as options to bash's builtin `echo`. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re^2: system function not handling string properly by hermes1908 (Novice) on Sep 06, 2013 at 21:21 UTC
$link does not contain any such characters. If you run the script on the sample sql file I linked to, the result is "www.youtube.com/watch?v=mark"	[reply]
Re^3: system function not handling string properly by choroba (Cardinal) on Sep 06, 2013 at 21:31 UTC
Try running a hexdump on the string. It seems it is UTF-16 encoded, there is a zero byte after each character. `echo` probably takes the null char as the end of string as in C. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^4: system function not handling string properly by McA (Priest) on Sep 06, 2013 at 21:45 UTC
Re^5: system function not handling string properly by choroba (Cardinal) on Sep 06, 2013 at 21:50 UTC
Some notes below your chosen depth have not been shown here
Re^2: system function not handling string properly by Anonymous Monk on Sep 08, 2013 at 09:27 UTC
Actually, since `system` is called correctly, the shell won't be invoked and it'll be the real `echo(1)` which only parses the `-n` option (AFAIK). Anyway, it's better to use something like `printf(1)` since it tends not to have surprising behaviour: `system('printf', '%s', $link);`	[reply] [d/l] [select]
Re: system function not handling string properly by McA (Priest) on Sep 06, 2013 at 21:02 UTC
Hi, what's about simply inserting a `print Dumper($link);` [download] to show us what you get from the database? McA	[reply] [d/l]
Re^2: system function not handling string properly by hermes1908 (Novice) on Sep 06, 2013 at 21:19 UTC
The script includes a print statement for this purpose. The print statement prints the contents of $link correctly, but system("echo", $link) only prints w. If you download the sample file I included and put it in the same directory of the script you can see the result yourself.	[reply]
Re^3: system function not handling string properly by McA (Priest) on Sep 06, 2013 at 21:36 UTC
Excuse me, I've overlooked that line. What is your OS? What shows 'which echo' on your system? This code works pretty well on my system: `#!/usr/bin/env perl use strict; use warnings; use 5.010; my $url = '"www.youtube.com/watch?v=mark"'; system('echo', $url); $url = "www.youtube.com/watch?v=mark"; system('echo', $url);` [download] McA	[reply] [d/l]