perl - 奇怪的 perl 行为与 glob

Question

use strict;
use warnings;
#only linux
#use diagnostics;

# - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - -
sub in_function {
    my $file = shift;

    glob($file) or die ("$file file was not found\n"); #this fails second time called

    # this is ok second time called
    #my @dummy = glob($file) or die ("$file file was not found\n");
}
# - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - -
my $file = "/tmp/file1*.pdf";
glob($file) or die ("$file file was not found\n");
in_function($file);
$file = "/tmp/file2*.pdf";
glob($file) or die ("$file file was not found\n");
in_function($file);

第一个 glob 没问题 第一个 in_function glob 没问题 第二个球没问题 第二个 in_function glob 失败 为什么在函数内调用时需要将 glob 分配给变量？

Answer 1

来自perldoc -f glob

In scalar context, glob iterates through such filename expansions, returning undef when the list is exhausted.

下面的方法可以解决这个问题:

() = glob($file) 
   or die ...;

但是您可能想知道匹配项是什么，因此您可以使用

my @matches = glob($file) 
   or die ...;