perl - Passing a quoted string to system() keeping quotes intact -

-

this problem applies perl v5.24.0 on windows 10

except simplest cases. problem passing command lines , parameter lists between programs. taking account effects of whitespace , shell metacharacters, possibly data remains intact on several levels of calls, can involve mess of escapes , quotation marks

the panacea has been use multiple-parameter form of system (which tries avoid calling shell intermediary) each parameter reliably separated without resorting quotes

a call this

system("dir \"c:\\program files\\\"")

is easier on eye written this

system('dir', 'c:\program files\\')

however, can see no way pass values include enclosing quotes

if write test program

show.pl

use data::dump; dd \@argv;

and call

system('show', 'xxx')

then output expect

["xxx"]

however, suppose want pass string "xxx". if try

system('show', '"xxx"')

then quotes stripped @ point along way , output identical preceding example

how make call system such output ["\"xxx\""]?

i have tried manner of escaping, solution evades me

the problem:

system($^x, '-e', 'say @argv', '"test"');

output:

test

that's broken![1]

solution:

use win32::shellquote qw( quote_system );  system(quote_system($^x, '-e', 'say @argv', '"test"'));

output:

"test"

  1. perl needs build command line if shell isn't used. unlike unix system call execute program takes path program , list of arguments, windows system call execute program takes command line, command line must built if shell avoided. appears perl builds command lines incorrectly.[2] why using system block list syntax doesn't help.

  2. in fact, it's application parse command line arguments! thankfully, there's system call that, standard has formed.


Comments

Post a Comment

Popular posts from this blog

sequelize.js - Sequelize group by with association includes id -

-
so when requesting group sequelize follows: return models.workingcalendar .findall({ attributes: [ 'workingcalendar.periodid', 'workingcalendar.date', 'period.name' ], include: [ { model: models.period, attributes: [] } ], where: { getsudoid: currentgetsudo.id, unitplantid: unitplantid }, group: ['workingcalendar.periodid', 'workingcalendar.date', 'period.name'], }); sequelize run query: select [workingcalendar].[id], [workingcalendar].[periodid], [workingcalendar].[date], [period].[name] [workingcalendars] [workingcalendar] left outer join [periods] [period] on [wor...
Read more

delphi - Take screenshot in webcam using VFrames in Console Application -

-
i'm doing program take picture of webcam using delphi xe2 , vframes achieve this, problem have figured out, in graphic application works fine, when use unit in console application, returns me error saying first chance exception @ $76b6b727. exception class eaccessviolation message 'access violation @ address 004a271b in module 'console.exe'. read of address 00000260'. process console.exe (3676) my unit : unit webcam; interface uses sysutils, windows, vcl.imaging.jpeg, vcl.graphics, vsample, vframes, classes; type twebcam = class private procedure newvideoframeevent(sender: tobject; width, height: integer; dataptr: pointer); public constructor create; destructor destroy; override; procedure capture_webcam(take_name: string); end; var web_image: tvideoimage; name_screen: string; implementation constructor twebcam.create; begin inherited create; end; destructor twebcam.destroy; begin inherited destroy; end; ...
Read more

php - Few issues in voting -

-
<?php include_once 'dbconnect.php'; include_once 'index_header.php'; $article_id = $_get['id']; $counter = 0; // select article db $sql = $con->query("select * posts post_id = '$article_id'"); if ($sql){ while($row = mysqli_fetch_assoc($sql)) { $select_title = $row['title']; $select_article = $row['article']; }} if(isset($_post['downvote'])){ $counter = $counter - 1; } if(isset($_post['upvote'])){ $counter = $counter + 1; if($counter<=1){ $insert_query = $con->query("insert votes(vote_count,post_id) values(1,'$article_id')"); } } $selet_votes = $con->query("select sum(vote_count) vote_count_sum votes post_id= '$article_id'"); if ($selet_votes){ $row_votes = mysqli_fetch_assoc($selet_votes); $votes = $r...
Read more