Perl Perl脚本中的一个内衬不起作用

Question

my text file contents

vi /root/text.conf

node.session.auth.authmethod = hello

so my one liner perl command replaces the above file contents by commenting with #. Works fine when run as single command

perl -pi -e 's/^(node.session.auth.authmethod\s*=\s*).*$/#\1hello/g' /root/text.conf

when the perl one liner code is executed inside perl script, it does not comment out the text.conf file contents.

$cmd ="perl -pi -e 's/^(node.session.auth.authmethod\s*=\s*).*$/#\1hello/g' /root/text.conf"

$line = `$cmd 2>&1`;$ret = $?;

Am I missing something while executing Perl one liner inside a Perl script.

Answer 1

Yes, use current perl process instead of forking new one. This is equivalent of your

perl -pi -e 's/^(node.session.auth.authmethod\s*=\s*).*$/#\1hello/g' /root/text.conf

one-liner,

use strict;
use warnings;

local $^I = "";
local @ARGV = "/root/text.conf";

while (<>) { 
  s/^(node.session.auth.authmethod\s*=\s*).*$/#\1hello/g;
  print;
}

Answer 2

Defining your $cmd the Variable $/ will be replaced by it's value (the line separator). Then the regex will not match your line.

Try using single quotes (along with proper escaping):

$cmd ='perl -pi -e \'s/^(node.session.auth.authmethod\s*=\s*).*$/#\1hello/g\' /root/text.conf'

$line = `$cmd 2>&1`;$ret = $?;

This will prevent perl from expanding variables.

Nevertheless mpapec's answer is right, why forking a new process?