1.shopt介绍
linux内建命令shopt允许shell在空闲时修改shell选项，它经常出现在启动文件中。但是，在一般脚本中也常出现，不过需要在版本2之后的bash中才支持。
2.样例
-->shopt用法
命令：
help shopt
[root@elasticsearch ~]# help shopt
shopt: shopt [-pqsu] [-o] [optname ...]
Set and unset shell options.
Change the setting of each shell option OPTNAME. Without any option
arguments, list all shell options with an indication of whether or not each
is set.
Options:
-o restrict OPTNAMEs to those defined for use with `set -o'
-p print each shell option with an indication of its status
-q suppress output
-s enable (set) each OPTNAME
-u disable (unset) each OPTNAME
Exit Status:
Returns success if OPTNAME is enabled; fails if an invalid option is
given or OPTNAME is disabled.
[root@elasticsearch ~]#样例：
[root@elasticsearch ~]# shopt -s cdspell #设置使用cd命令时，允许产生少量的拼写错误
[root@elasticsearch ~]# cd /hpme #应该是"/home"
/home
[root@elasticsearch home]# pwd
/home #正常进入/home目录，说明拼写错误被纠正了
[root@elasticsearch home]#-->被允许修改的shell选项
[root@elasticsearch home]# shopt
autocd off
cdable_vars off
cdspell on #常用
checkhash off
checkjobs off
checkwinsize on
cmdhist on
compat31 off
compat32 off
compat40 off
compat41 off
direxpand off
dirspell off
dotglob off #常用
execfail off
expand_aliases on
extdebug off
extglob off #常用
extquote on
failglob off
force_fignore on
globstar off
gnu_errfmt off
histappend on
histreedit off
histverify off
hostcomplete on
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 #常用
progcomp on
promptvars on
restricted_shell off
shift_verbose off
sourcepath on
syslog_history off
xpg_echo off
[root@elasticsearch home]#
