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代码： 全选

#! /bin/bash

clr_dir=
clearDir()
{
	if [ -d $clr_dir ]
	then
		rm -R $clr_dir/*
		echo "$clr_dir --- cleared."
	else
		echo "$clr_dir --- not exist!"
	fi
}

clr_dir="~/.thumbnails"
clearDir

代码： 全选

+ clr_dir=
+ clr_dir='~/.thumbnails'
+ clearDir
+ '[' -d '~/.thumbnails' ']'
+ echo '~/.thumbnails --- not exist!'
~/.thumbnails --- not exist!

代码： 全选

   Tilde Expansion
       If a word begins with an unquoted tilde character  (`~'),  all  of  the
       characters  preceding  the  first unquoted slash (or all characters, if
       there is no unquoted slash) are considered a tilde-prefix.  If none  of
       the  characters  in  the tilde-prefix are quoted, the characters in the
       tilde-prefix following the tilde are treated as a possible login  name.
       If  this  login name is the null string, the tilde is replaced with the
       value of the shell parameter HOME.  If HOME is unset, the  home  direc-
       tory  of  the  user executing the shell is substituted instead.  Other-
       wise, the tilde-prefix is replaced with the home  directory  associated
       with the specified login name.

       If  the  tilde-prefix  is  a  `~+', the value of the shell variable PWD
       replaces the tilde-prefix.  If the tilde-prefix is a `~-', the value of
       the  shell variable OLDPWD, if it is set, is substituted.  If the char-
       acters following the tilde in the tilde-prefix consist of a  number  N,
       optionally  prefixed  by  a  `+' or a `-', the tilde-prefix is replaced
       with the corresponding element from the directory stack, as it would be
       displayed by the dirs builtin invoked with the tilde-prefix as an argu-
       ment.  If the characters following the tilde in the  tilde-prefix  con-
       sist of a number without a leading `+' or `-', `+' is assumed.

       If the login name is invalid, or the tilde expansion fails, the word is
       unchanged.

       Each variable assignment is checked for unquoted tilde-prefixes immedi-
       ately following a : or the first =.  In these cases, tilde expansion is
       also performed.  Consequently, one may use file names  with  tildes  in
       assignments  to  PATH,  MAILPATH, and CDPATH, and the shell assigns the
       expanded value.

代码： 全选

biff@lenovo:~$ sh a
[/home/biff]
[$HOME]
[~/]
[~/]
biff@lenovo:~$ cat a

echo "[$HOME]"
echo '[$HOME]'
echo "[~/]"
echo '[~/]'
biff@lenovo:~$

代码： 全选

tusooa@tusooa-laptop:~$ sh bashtest
/home/tusooa/
~/
/home/tusooa
/home/tusooa
tusooa@tusooa-laptop:~$