之前稍微了解过shopt命令，但用的较少，所以印象不深，这次无意中碰到了，刚好学习学习。
怎样遍历移除项目中的所有 .pyc 文件 ？
如果你使用的是linux或者mac，在终端执行这样的操作：
find /tmp -name "*.pyc" | xargs rm -rf
如果提示Permission denied，则使用：
sudo find /tmp -name "*.pyc" | xargs rm -rf
将上面的/tmp替换成工程目录即可。这个命令会遍历删除工程目录（含子目录）下的pyc文件。
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rm **/*.pyc
补充说明：在bash下要在~/.bashrc中添加shopt -s globstar
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在打包时忽略 .pyc 文件或许是个更方便的办法。
tar和zip都可以加上 –exclude=*.pyc 参数来排除 pyc 文件
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find -iname "*.pyc" -exec rm -f {} ;
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find . -type f -name "*.py[co]" -delete
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上面的几个find命令的示例其实我都知道，这里感兴趣的主要在于：
rm **/*.pyc
这个方法，补充说明有“在bash下要在~/.bashrc中添加shopt -s globstar”
刚好前段时间看到过一篇文章：
需求：
一个日志目录，里头存着很多 00, 01, 02 … 31 的日期目录，如何列示出00到12号之间的所有目录？也就是说，如何在文件名上面，使用正则？
解法：
# shopt -s extglob # ls -al +(0[0-9]|1[0-3])
说明：
Ø 平时shell的通配符，只是通配语义，不是正则语义
Ø 加上这个 extglob 之后，才能是正则语义
Ø 语法格式是 +(正则)
—————————-
去Ubuntu上看看（Bash的版本为：GNU bash, version 4.3.11(1)-release (i686-pc-linux-gnu)）：
# shopt -s autocd execfail lastpipe cdable_vars expand_aliases lithist cdspell extdebug login_shell checkhash extglob mailwarn checkjobs extquote nocaseglob checkwinsize failglob nocasematch cmdhist force_fignore no_empty_cmd_completion compat31 globasciiranges nullglob compat32 globstar progcomp compat40 gnu_errfmt promptvars compat41 histappend restricted_shell compat42 histreedit shift_verbose complete_fullquote histverify sourcepath direxpand hostcomplete xpg_echo dirspell huponexit dotglob interactive_comments
搜索关键字：
找到的有效链接{extglob}：
- scripting – What does the syntax on this shell command with extglob mean? – Unix & Linux Stack Exchange
- Patterns and pattern matching [Bash Hackers Wiki]
- glob – Greg’s Wiki
- bash – How can I use inverse or negative wildcards when pattern matching in a unix/linux shell? – Stack Overflow
GNU官方说明：Bash Reference Manual: The Shopt Builtin
另一个shopt的选项{globstar}：
better, simpler searching and scripting with bash globstar « ShellRunner
Globstar is a feature not typically enabled, but present in bash 4+, and it allows you to do more easily select files in bash, using a double star **.
For example, if you want to every .text file, in all subdirectories, you no longer even need to use the find command.
ls **/*.text
The ** here will traverse any number of directories, not just the current directory. Here’s another very useful, easy to remember example. Ever want to find a line of text somewhere in a huge pile of files, but you know some part of the file name? You can do a recursive grep to easily find it, without some abstruse find command.
grep -r needle **/*haystack*
To begin using globstar, you need to enable it. It should be the default, if you ask me, but enabling is simple. From the terminal, type:
shopt -s globstar
You’ll probably want to add that line to your ~/.bashrc file, too, so it’s enabled every time you open a terminal or login.
在我的VPS上globstar默认是关闭的：
# shopt globstar globstar off
而，extglob默认却是开启的：
# shopt extglob extglob on
- bash4 – Unable to enable globstar in Bash 4 – Stack Overflow
- Globstar: New Bash Globbing Option | Linux Journal
在Stackoverflow上有一个问题对我而言很有启发意义：
http://stackoverflow.com/questions/17191622/why-would-i-not-leave-extglob-enabled-in-bash
提问者给出了一个思考：
All the answers that used ‘shopt -s extglob’ also mentioned ‘shopt -u extglob’ to turn it off. Why would I want to turn something so useful off? Indeed why isn’t it on by default? Presumably it has the potential for giving some nasty surprises. What are they?
所有的答案都告诉我使用“shopt -s extglob”打开extglob，使用“shopt -u extglob”关掉extglob，但是为什么我还是想将这么有用的一个选项关掉呢？为什么这么有用的选项在默认状态下没有被开启？难道是因为这可能会导致一些糟糕的意外？如果是的话，会导致哪些问题呢？
—
回答简洁明了：
No nasty surprises — default-off behavior is only there for compatibility with traditional, standards-compliant pattern syntax.
默认状态下没有开启不代表这是不好的特性，仅仅只是兼容性的需要而已。
查看shopt的选项都是些什么状态，直接输入：shopt然后回车即可
# shopt autocd off cdable_vars off cdspell off checkhash off checkjobs off checkwinsize on cmdhist on compat31 off compat32 off compat40 off compat41 off compat42 off complete_fullquote on direxpand off dirspell off dotglob off execfail off expand_aliases on extdebug off extglob on extquote on failglob off force_fignore on globstar off globasciiranges off gnu_errfmt off histappend on histreedit off histverify off hostcomplete off huponexit off interactive_comments on lastpipe off lithist off login_shell on mailwarn off no_empty_cmd_completion off nocaseglob off nocasematch off nullglob off progcomp on promptvars on restricted_shell off shift_verbose off sourcepath on xpg_echo off