当我尝试使用curl和管道操作符直接传给php的去执行下载回来的install的时候报错了：

$ curl -s https://getcomposer.org/installer | php
#!/usr/bin/env php
All settings correct for using Composer
Downloading...
The download is corrupt, retrying...
Downloading...
The download is corrupt, retrying...
Downloading...
The download is corrupt (internal corruption of phar "/work/doc/composer.phar" (truncated entry)), aborting.

然后我手动下载了install：

$ curl -s https://getcomposer.org/installer > composer

然后手动跟踪错误出在了哪里，然后跟踪到了一个try...catch语句：

......

try {
            // test the phar validity
            echo $file;
            $phar = new Phar($file);
            // free the variable to unlock the file
            unset($phar);
            break;
        } catch (Exception $e) {
            if (!$e instanceof UnexpectedValueException && !$e instanceof PharException) {
                throw $e;
            }
            unlink($file);
            if ($retries) {
                if (!$quiet) {
                   out('The download is corrupt, retrying...', 'error');
                }
            } else {
                out('The download is corrupt ('.$e->getMessage().'), aborting.', 'error');
                exit(1);
            }
        }

......

当 new Phar的时候出现了错误，于是我把这段代码拿出来，单独执行之后，php报了这样的错误：

$ cat test.php 
<?php

$file = '/work/doc/composer.phar';

$phar = new Phar($file);

unset($phar);

然后执行这个test.php,看到这样的错误：

$ php test.php 
PHP Fatal error:  Uncaught exception 'UnexpectedValueException' with message 'internal corruption of phar "/work/doc/composer.phar" (__HALT_COMPILER(); not found)' in /work/doc/test.php:5
Stack trace:
#0 /work/doc/test.php(5): Phar->__construct('/work/doc/compo...')
#1 {main}
  thrown in /work/doc/test.php on line 5

Fatal error: Uncaught exception 'UnexpectedValueException' with message 'internal corruption of phar "/work/doc/composer.phar" (__HALT_COMPILER(); not found)' in /work/doc/test.php:5
Stack trace:
#0 /work/doc/test.php(5): Phar->__construct('/work/doc/compo...')
#1 {main}
  thrown in /work/doc/test.php on line 5

但是我已经有一份下载回来的脚本命名为 composer.phar,我把test.php命名为composer.phar也不行，下边是我的php的编译参数：

./configure --prefix=/opt/php/default --with-config-file-path=/opt/php/default/etc --with-mysql --with-mysqli --with-iconv-dir --with-freetype-dir --with-jpeg-dir --with-png-dir --with-zlib --with-libxml-dir --enable-xml --disable-rpath --enable-bcmath --enable-shmop --enable-sysvsem --enable-inline-optimization --with-curl --with-curlwrappers --enable-mbregex --enable-fpm --enable-mbstring --with-mcrypt --with-gd --enable-gd-native-ttf --with-openssl --with-mhash --enable-pcntl --enable-sockets --with-ldap --with-ldap-sasl --with-libdir=lib64 --with-xmlrpc --enable-zip --enable-soap --with-pear --enable-pdo --with-pdo-mysql --with-gettext --enable-exif --enable-wddx --enable-calendar --enable-ftp --enable-dba --enable-sysvmsg --enable-sysvshm --enable-debug --enable-maintainer-zts --with-pcre-regex --enable-gd-jis-conv --with-apxs2=/opt/apache/default/bin/apxs