我有一个带命令行的脚本的问题.. PHP脚本永远不会继续..

试图直接通过putty调用命令行,它输出很多错误但是立即返回/完成.为什么不返回PHP呢？

它适用于其他PDF文件,但不适用于此

PDF格式

http://docdro.id/b0M5vfw

码

$Cmd = new Command;
if($err = $Cmd->exec('/VAR/bin/poppler-0.51.0/utils/pdfimages -list /var/test.pdf')){
    echo "ERR: $err\n";
}
echo "continue\n";

类

class Command {
    PRivate $descriptorsPEc;

    private $output = '';

    private $process;
    private $pipes = [];

    public function __construct(){
        $this->descriptorspec = [
            0 => ['pipe','r'],// stdin
            1 => ['pipe','w'],// stdout
            2 => ['pipe','w']  // stderr
        ];
    }

    public function output(): string{
        return $this->output;
    }

    public function close(){
        foreach($this->pipes as $pipe){
            if(is_resource($pipe)){
                fclose($pipe);
            }
        }

        proc_close($this->process);
    }

    public function exec(string $Syntax){
        $this->process = proc_open($Syntax,$this->descriptorspec,$this->pipes);
        fclose($this->pipes[0]);

        $this->output = stream_get_contents($this->pipes[1]);

        $stderr = stream_get_contents($this->pipes[2]);

        $this->close();

        return $stderr;
    }
}

错误

# /var/bin/poppler-0.51.0/utils/pdfimages -list /var/test.pdf
page   num  type   width height color comp bpc  enc interp  object ID x-ppi y-ppi size ratio
--------------------------------------------------------------------------------------------
   1     0 image    2154   303  rgb     3   8  jpeg   yes  [inline]     289   292    -    -
Syntax Error (50560): Illegal character '>'
Syntax Error (50560): UnkNown operator '<10><07><82>;w<ad><a2><b4>2r<1f><10><07><8f>~j<c4>Hq<CF>Z<86>'
Syntax Error (50568): UnkNown operator '<0f><b5>X<8f><ae><d0>:<d7>DU<91><cb>'v'
Syntax Error (50568): Illegal character ')'

........

Syntax Error (66698): Illegal character <04> in hex string
Syntax Error (66699): Illegal character <ff> in hex string
Syntax Error (66699): Illegal character <c1> in hex string
Syntax Error (66705): UnkNown operator '<9b>'
Syntax Error (66714): Illegal character ')'
Syntax Error (66714): UnkNown operator '<bc>q<ff>'
Syntax Error (66720): UnkNown operator '<05>6<f8><c2><fa><d7><c3>?<f8>'
Syntax Error (66741): UnkNown operator '<df><ec><99><e1>-'
Syntax Error (66743): UnkNown operator ']'
Syntax Error (66762): UnkNown operator '<cc>'
Syntax Error: Unterminated string
Syntax Error: End of file inside array
Syntax Error: End of file inside array
Syntax Error: Leftover args in content stream

$Cmd = new Command;

try {
    $err = $Cmd->exec('/var/bin/poppler-0.51.0/utils/pdfimages - list/var/test.pdf')){
} catch (Exception $e) {
    var_LOG($e);
}

echo "continue\n";