This is a pure Perl parameters passing issue. I cannot use Get::Opt as it is not installed on every machine.
I need to pass parameters with spaces and other special chars sometimes. Three scripts to demo the process. Is there a better way to do this?
[gliang#www stackoverflow]$ perl parameter_wrapper.pl
prep.pl #<5> parameters
prep_v2.pl #<5> parameters
<aaa_777-1>
<bbb-6666-2>
<Incomplete QA>
<-reason>
<too long, mail me at ben#example.com :)>
cat parameter_wrapper.pl
#!/usr/bin/perl -w
use strict;
# call prep.pl with 5 parameters
my $cmd = "./prep.pl aaa_777-1 bbb-6666-2 'Incomplete QA' -reason 'too long, mail me at ben\#example.com :)\n'";
system($cmd);
cat prep.pl
#!/usr/bin/perl -w
use strict;
my #parameters = #ARGV;
my $count = scalar(#parameters);
my #parameters_new = wrap_parameters(#parameters);
my $cmd = "./prep_v2.pl #parameters_new";
print "prep.pl #<$count> parameters\n";
system($cmd);
sub wrap_parameters {
my #parameters = #_;
my #parameters_new;
foreach my $var(#parameters) {
$var = quotemeta($var);
push(#parameters_new, $var);
}
return #parameters_new;
}
cat prep_v2.pl
#!/usr/bin/perl -w
use strict;
my #parameters = #ARGV;
my $count = scalar(#parameters);
print "prep_v2.pl #<$count> parameters\n";
foreach my $var (#parameters) {
#print "<$var>\n";
}
Getopt::Long has been part of the Perl core since Perl 5 was first released in 1994. Are you sure it's not available on the machines you're looking to deploy on? In your comment you refer to it as "Get::Opt", so could you have made a mistake while checking the machines?
Related
I am trying to pass arguments from one Perl script to another. Some of the arguments contain spaces.
I am reading in a comma-delimited text file and splitting each line on the comma.
my ($jockey, $racecourse, $racenum, $hnamenum, $trainer, $TDRating, $PRO) = split(/,/, $line);
The data in the comma-delimited text file look as follows:
AARON LYNCH,WARRNAMBOOL,RACE 1,DAREBIN (8),ERIC MUSGROVE,B,1
When I print out each variable, from the parent script, they look fine (as above).
print "$jockey\n";
print "$racecourse\n";
print "$racenum\n";
print "$hnamenum\n";
print "$trainer\n";
print "$TDRating\n";
print "$PRO\n";
AARON LYNCH
WARRNAMBOOL
RACE 1
DAREBIN (8)
ERIC MUSGROVE
B
1
When I pass the arguments to the child script (as follows), the arguments are passed incorrectly.
system("perl \"$bindir\\narrative4.pl\" $jockey $racecourse $racenum $hnamenum $trainer $TDRating $PRO");
AARON
LYNCH
WARRNAMBOOL
RACE
1
DAREBIN
(8)
As you can see, $ARGV[0] becomes AARON, $ARGV[1] becomes LYNCH, $ARGV[2] becomes WARRNAMBOOL, and so on.
I have investigated adding quotes to the arguments using qq, quotemeta and Win32::ShellQuote, unfortunately, even if I pass qq{"$jockey"}, the quotes are still stripped before they reach the child script, so they must be protected in some way.
I not sure if either of the aforementioned solutions is the correct but I'm happy to be corrected.
I'd appreciate any suggestions. Thanks in advance.
Note: I am running this using Strawberry Perl on a Windows 10 PC.
Note2: I purposely left out use strict; & use warnings; in these examples.
Parent Script
use Cwd;
$dir = getcwd;
$bin = "bin"; $bindir = "$dir/$bin";
$infile = "FINAL-SORTED-JOCKEY-RIDES-FILE.list";
open (INFILE, "<$infile") or die "Could not open $infile $!\n";
while (<INFILE>)
{
$line = $_;
chomp($line);
my ($jockey, $racecourse, $racenum, $hnamenum, $trainer, $TDRating, $PRO) = split(/,/, $line);
print "$jockey\n";
print "$racecourse\n";
print "$racenum\n";
print "$hnamenum\n";
print "$trainer\n";
print "$TDRating\n";
print "$PRO\n";
system("perl \"$bindir\\narrative4.pl\" $jockey $racecourse $racenum $hnamenum $trainer $TDRating $PRO");
sleep (1);
}
close INFILE;
exit;
Child Script
$passedjockey = $ARGV[0];
$passedracecourse = $ARGV[1];
$passedracenum = $ARGV[2];
$passedhnamenum = $ARGV[3];
$passedtrainer = $ARGV[4];
$passedTDRating = $ARGV[5];
$passedPRO = $ARGV[6];
print "$passedjockey\n";
print "$passedracecourse\n";
print "$passedracenum\n";
print "$passedhnamenum\n";
print "$passedtrainer\n";
print "$passedTDRating\n";
print "$passedPRO\n\n";
That whole double-quoted string that is passed to system is first evaluated and thus all variables are interpolated -- so the intended multi-word arguments become merely words in a list. So in the end the string has a command to run with individual words as arguments.
Then, even if you figure out how to stick which quotes in there just right, so to keep those multi-word arguments "together," there's still a chance of a shell being invoked, in which case those arguments again get broken up into words before being passed to the program.
Instead of all this use the LIST form of system. The first argument is then the name of the program that will be directly executed without a shell (see docs for some details on that), and the remaining arguments are passed as they are to that program.
parent
use warnings;
use strict;
use feature 'say';
my #args = ('first words', 'another', 'two more', 'final');
my $prog = 'print_args.pl';
system($prog, #args) == 0
or die "Error w/ system($prog, #args): $!";
and the invoked print_args.pl
use warnings;
use strict;
use feature 'say';
say for #ARGV;
The #ARGV contains arguments passed to the program at invocation. There's more that can be done to inspect the error, see docs and links in them.†
By what you show you indeed don't need a shell and the LIST form is generally easy to recommend as a basic way to use system, when the shell isn't needed. If you were to need shell's capabilities for something in that command then you'd have to figure out how to protect those spaces.
† And then there are modules for running external programs that are far better than system & Co. From ease-of-use to features and power:
IPC::System::Simple, Capture::Tiny, IPC::Run3, IPC::Run.
I want to take arguments as an array of hashes by using Getopt::Long in my script.
Consider the following command line example:
perl testing.pl --systems id=sys_1 ip_address=127.0.0.1 id=sys_2 ip_address=127.0.0.2
For the sake of simplicity, I'm using two systems and only two sub arguments of each system, i.e., id and ip_address. Ideally, the number of systems is dynamic; it may contain 1, 2 or more and so with the number of arguments of each system.
My script should handle these arguments in such a way that it will store in #systems array and each element will be a hash containing id and ip_address.
Is there any way in Getopt::Long to achieve this without parsing it myself?
Following is pseudocode for what I'm trying to achieve:
testing.pl
use Getopt::Long;
my #systems;
GetOptions('systems=s' => \#systems);
foreach (#systems) {
print $_->{id},' ', $_->{ip_address};
}
Here is an attempt, there might be more elegant solutions:
GetOptions('systems=s{1,}' => \my #temp );
my #systems;
while (#temp) {
my $value1 = shift #temp;
$value1 =~ s/^(\w+)=//; my $key1 = $1;
my $value2 = shift #temp;
$value2 =~ s/^(\w+)=//; my $key2 = $1;
push #systems, { $key1 => $value1, $key2 => $value2 };
}
for (#systems) {
print $_->{id},' ', $_->{ip_address}, "\n";
}
Output:
sys_1 127.0.0.1
sys_2 127.0.0.2
I actually think this is a design problem, more than a problem with GetOpt - the notion of supporting multiple, paired arguments passed as command line arguments I think is something that you'd be far better off avoiding.
There's a reason that GetOpt doesn't really support it - it's not a scalable solution really.
How about instead just reading the values from STDIN?:
#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
my %systems = do { local $/; <DATA> } =~ m/id=(\w+) ip_address=([\d\.]+)/mg;
print Dumper \%systems;
And then you'd be able to invoke your script as:
perl testing.pl <filename_with_args>
Or similar.
And if you really must:
my %systems = "#ARGV" =~ m/id=(\w+) ip_address=([\d\.]+)/g;
Both of the above work for multiple parameters.
However, your comment on another post:
I can't because I'm fetching parameters from database and converting them into command line and then passing it to the script using system command $cmd_lines_args = '--system --id sys_1 --ip_address 127.0.0.0.1'; system("perl testing.pl $cmd_lines_args"); $cmd_lines_args I'll generate dynamically using for loop by reading from database
.. that makes this an XY Problem.
Don't do it like that:
open ( my $script, '|-', "perl testing.pl" );
print {$script} "id=some_id ip_address=10.9.8.7\n";
print {$script} "id=sys2 ip_address=10.9.8.7\n";
etc.
What you are describing,
--systems id=sys_1 ip_address=127.0.0.1 id=sys_2 ip_address=127.0.0.2
appears to be one option that takes a variable number of arguments that are pairs, and come in multiples of two. Getopt::Long's "Options with multiple values" lets you do the following:
GetOptions('systems=s{2,4}' => \#systems);
This lets you specify 2, 3 or 4 arguments, but it does not have syntax for "any even number of arguments" (to cover an arbitrary number of pairs beyond two), and you still have to unpack the id=sys_1 manually then. You can write a user-defined subroutine that handles the processing of --systems' arguments (but does not take into account missing id=...s):
my $system;
my %systems;
GetOptions('systems=s{,}' => sub {
my $option = shift;
my $pair = shift;
my ($key, $value) = split /=/, $pair;
$system = $value if $key eq 'id';
$systems{$system} = $value if $key eq 'ip_address';
});
I would however prefer one of the following schemes:
--system sys_1 127.0.0.1 --system sys_2 127.0.0.1
--system sys_1=127.0.0.1 --system sys_2=127.0.0.1
They're achieved with the following:
GetOptions('system=s{2}', \#systems);
GetOptions('system=s%', \#systems);
I would just parse the --systems arg and quote the "hashes" like this:
perl testing.pl --systems "id=s1 ip_address=127.0.0.1 id=s2 ip_address=127.0.0.2"
Parse like perhaps so:
my($systems,#systems);
GetOptions('systems=s' => \$systems);
for(split/\s+/,$systems){
my($key,$val)=split/=/,$_,2;
push #systems, {} if !#systems or exists$systems[-1]{$key};
$systems[-1]{$key}=$val;
}
print "$_->{id} $_->{ip_address}\n" for #systems;
Prints:
sys_1 127.0.0.1
sys_2 127.0.0.2
I have a Perl script which I am trying to understand. I am quoting first few lines of the script (abc.pl)
#!/usr/bin/perl
use strict;
use DateTime;
use File::Temp;
use Math::Complex;
use Getopt::Long;
use TauP::Time;
use Seed::Response;
use lib '/usr/lib/perl5';
use Seismogram::SAC;
my(#input,$output);
GetOptions('input=s{,}' => \#input, 'output=s' => \$output);
open my $out_fp,">$output";
foreach my $file (<#input>)
{
my $phase = 'S';
if ( $file =~ /BHZ/ ) { $phase = 'P';}
my $decData = File::Temp->new();
decimateData($file,$decData);
my($sac) = readSAC($decData);
my($resp) = readResponse($sac);
}
I have a few files which I have listed in "list".
Can anyone please let me understand how should I input "list" and output filenames to the perl script.
my(#input,$output);
This line declares variables used on next line (#input is an array of input files, $output is scalar for output filename)
GetOptions('input=s{,}' => \#input, 'output=s' => \$output);
GetOptions is a function from module Getopt::Long and this line parses commandline options and fills previously declared variables. You should read module documentation
Is there a (best) way to check, if $uri was passed in single quotes?
#!/usr/local/bin/perl
use warnings;
use 5.012;
my $uri = shift;
# uri_check
# ...
Added this example, to make my problem more clear.
#!/usr/local/bin/perl
use warnings;
use 5.012;
use URI;
use URI::Escape;
use WWW::YouTube::Info::Simple;
use Term::Clui;
my $uri = shift;
# uri check here
$uri = URI->new( $uri );
my %params = $uri->query_form;
die "Malformed URL or missing parameter" if $params{v} eq '';
my $video_id = uri_escape( $params{v} );
my $yt = WWW::YouTube::Info::Simple->new( $video_id );
my $info = $yt->get_info();
my $res = $yt->get_resolution();
my #resolution;
for my $fmt ( sort { $a <=> $b } keys %$res ) {
push #resolution, sprintf "%d : %s", $fmt, $res->{$fmt};
}
# with an uri-argument which is not passed in single quotes
# the script doesn't get this far
my $fmt = choose( 'Resolution', #resolution );
$fmt = ( split /\s:\s/, $fmt )[0];
say $fmt;
You can't; bash parses the quotes before the string is passed to the Perl interpreter.
To expand on Blagovest's answer...
perl program http://example.com/foo?bar=23&thing=42 is interpreted by the shell as:
Execute perl and pass it the arguments program and http://example.com/foo?bar=23
Make it run in the background (that's what & means)
Interpret thing=42 as setting the environment variable thing to be 42
You should have seen an error like -bash: thing: command not found but in this case bash interpreted thing=42 as a valid instruction.
The shell handles the quoting and Perl has no knowledge of that. Perl can't issue an error message, it just sees arguments after shell processing. It never even sees the &. This is just one of those Unix things you'll have to learn to live with. The shell is a complete programming environment, for better or worse.
There are other shells which dumb things down quite a bit so you can avoid this issue, but really you're better off learning the quirks and powers of a real shell.
I have a hosts file that looks like this:
10.10.10.1 myserver1 myserver1alias
10.10.10.2 myserver2 myserver2alias
I'm looking for a way using perl to pass in an argument of myserver1 and have it return myserver1alias, likewise if I pass in myserver2 it should return myserver2alias. Any suggestions?
From the command line:
$ perl -lane 'print $F[-1] if $F[1] eq "myserver1"' /etc/hosts
while(<>){
if (/myserver1/){
#s = split /myserver1/,$_,2;
print $s[-1];
}
}
The quick-and-dirty way is:
perl -nE 'say $1 if /myserver1\s+(\w+)$/' path/to/hostfile
You might need to do queries similar to this from time to time, so you could probably make a reusable chunk of code to do this for you. Something like:
#!/usr/bin/perl
use strict;
use warnings;
use 5.10;
use HostFileParser;
my $host = HostFileParser->parse("path/to/hostfile")
my $server = $host->find(server => "myserver1")
say $server->alias;
Of course, I'm not going to "give you teh codez" for all of that. ;)
(These answers assume Perl 5.10, but if you don't have it the changes are just say $x => print "$x\n", or sub say { print "#_\n" }.)