本篇文章主要目的是：通过一个实例说明 where 命令的用途。

今天，在项目目录下执行svn info突然报错：

ccc ➤ svn info
svn: E155021: This client is too old to work with the working copy at
'/Users/luzuheng/PhpstormProjects/vagrant/data/ccc' (format 31).
You need to get a newer Subversion client. For more details, see
  http://subversion.apache.org/faq.html#working-copy-format-change

提示svn版本不够高。

ccc ➤ svn --version
svn, version 1.7.22 (r1694152)
   compiled Feb 10 2016, 16:22:46

Copyright (C) 2015 The Apache Software Foundation.
This software consists of contributions made by many people; see the NOTICE
file for more information.
Subversion is open source software, see http://subversion.apache.org/

The following repository access (RA) modules are available:

* ra_neon : Module for accessing a repository via WebDAV protocol using Neon.
  - handles 'http' scheme
  - handles 'https' scheme
* ra_svn : Module for accessing a repository using the svn network protocol.
  - handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
  - handles 'file' scheme
* ra_serf : Module for accessing a repository via WebDAV protocol using serf.
  - handles 'http' scheme
  - handles 'https' scheme

看来确实是版本低了，但是奇怪的是前两天还可以用的，说明我的机器上肯定有多个版本的svn。

确定当前用的是哪个svn：

ccc ➤ which svn
/usr/bin/svn

查看机器上有哪些svn:

ccc ➤ where svn
/usr/bin/svn
/usr/local/bin/svn
/usr/bin/svn

果然有多个，至于为啥显示了两次/usr/bin/svn，后面再解决。

ccc ➤ /usr/local/bin/svn --version
svn, version 1.8.11 (r1643975)
   compiled Jan 18 2015, 06:42:12 on x86_64-apple-darwin14.1.0

Copyright (C) 2014 The Apache Software Foundation.
This software consists of contributions made by many people;
see the NOTICE file for more information.
Subversion is open source software, see http://subversion.apache.org/

The following repository access (RA) modules are available:

* ra_svn : Module for accessing a repository using the svn network protocol.
  - with Cyrus SASL authentication
  - handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
  - handles 'file' scheme
* ra_serf : Module for accessing a repository via WebDAV protocol using serf.
  - using serf 1.3.8
  - handles 'http' scheme
  - handles 'https' scheme

/usr/local/bin/svn下的是1.8的，再去项目里执行svn info:

ccc ➤ /usr/local/bin/svn info
Path: .
Working Copy Root Path: /XXXXXXXXX/ccc
URL: http://svnXXXXXXXX/trunk
Relative URL: ^/XXX/trunk
Repository Root: http://XXXXX/
Repository UUID: xxx
Revision: xxxx
Node Kind: directory
Schedule: normal
Last Changed Author: aaa
Last Changed Rev: xxxx
Last Changed Date: 2016-09-21 17:50:31 +0800 (三, 21  9 2016)

果然可以了！

设置一下别名。vim ~/.zshrc 增加一行 alias svn=/usr/local/bin/svn，source一下，再执行svn --version

➜  ccc  svn --version
svn, version 1.8.11 (r1643975)
   compiled Jan 18 2015, 06:42:12 on x86_64-apple-darwin14.1.0

Copyright (C) 2014 The Apache Software Foundation.
This software consists of contributions made by many people;
see the NOTICE file for more information.
Subversion is open source software, see http://subversion.apache.org/

The following repository access (RA) modules are available:

* ra_svn : Module for accessing a repository using the svn network protocol.
  - with Cyrus SASL authentication
  - handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
  - handles 'file' scheme
* ra_serf : Module for accessing a repository via WebDAV protocol using serf.
  - using serf 1.3.8
  - handles 'http' scheme
  - handles 'https' scheme

OK了！

再回头看where svn的时候为啥显示了两次/usr/bin/svn。怀疑跟环境变量PATH有关

ccc ➤ echo $PATH
/usr/local/Cellar/php55/5.5.22/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin

果然有两个 /usr/bin,同样/bin 和 /usr/sbin 和 /sbin 也有两个。

查看zsh配置:

ccc ➤ cat ~/.zshrc|grep PATH
export PATH="/usr/local/Cellar/php55/5.5.22/bin:/usr/bin:/bin:/usr/sbin:/sbin:$PATH"

原来问题出在这，修改文件后, source ~/.zshrc,然后再看

➜  ccc  where svn
svn: aliased to /usr/local/bin/svn
/usr/local/bin/svn
/usr/bin/svn

OK了，因为svn的问题发现环境变量配置的错误，也算XXXX。 求XXXX这个成语……想不出来。。。

后续：

隔了两个小时，突然想到where svn结果显示顺序是按照PATH环境变量优先级来的，前两天项目中svn info还是可用的，今天突然不能用的原因就是昨天我调整了PATH，也就是说现在我修复完PATH之后不用别名也是优先使用的1.8版本的svn。 确认一下，先删除alias,然后：

└─[$]> where svn
/usr/local/bin/svn
/usr/bin/svn

─[$]> svn --version
svn, version 1.8.11 (r1643975)
   compiled Jan 18 2015, 06:42:12 on x86_64-apple-darwin14.1.0

Copyright (C) 2014 The Apache Software Foundation.
This software consists of contributions made by many people;
see the NOTICE file for more information.
Subversion is open source software, see http://subversion.apache.org/

The following repository access (RA) modules are available:

* ra_svn : Module for accessing a repository using the svn network protocol.
  - with Cyrus SASL authentication
  - handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
  - handles 'file' scheme
* ra_serf : Module for accessing a repository via WebDAV protocol using serf.
  - using serf 1.3.8
  - handles 'http' scheme
  - handles 'https' scheme

果然啊…… 原来PATH错误才是导致项目里svn突然用不了的罪魁祸首！！！

之前还在庆幸因为svn问题发现了PATH错误……

蜜汁尴尬。。。

继续求一发 XXXX 成语...

语死早。。。