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!
qq274980 写了：不要用 ~/.thum ，改用 $HOME/.thum
代码： 全选
Tilde Expansion
If a word begins with an unquoted tilde character (`~'), all of the
characters preceding the first unquoted slash (or all characters, if
there is no unquoted slash) are considered a tilde-prefix. If none of
the characters in the tilde-prefix are quoted, the characters in the
tilde-prefix following the tilde are treated as a possible login name.
If this login name is the null string, the tilde is replaced with the
value of the shell parameter HOME. If HOME is unset, the home direc-
tory of the user executing the shell is substituted instead. Other-
wise, the tilde-prefix is replaced with the home directory associated
with the specified login name.
If the tilde-prefix is a `~+', the value of the shell variable PWD
replaces the tilde-prefix. If the tilde-prefix is a `~-', the value of
the shell variable OLDPWD, if it is set, is substituted. If the char-
acters following the tilde in the tilde-prefix consist of a number N,
optionally prefixed by a `+' or a `-', the tilde-prefix is replaced
with the corresponding element from the directory stack, as it would be
displayed by the dirs builtin invoked with the tilde-prefix as an argu-
ment. If the characters following the tilde in the tilde-prefix con-
sist of a number without a leading `+' or `-', `+' is assumed.
If the login name is invalid, or the tilde expansion fails, the word is
unchanged.
Each variable assignment is checked for unquoted tilde-prefixes immedi-
ately following a : or the first =. In these cases, tilde expansion is
also performed. Consequently, one may use file names with tildes in
assignments to PATH, MAILPATH, and CDPATH, and the shell assigns the
expanded value.
不完全正确，简单试试就知道了，linuxleio 写了：shell script里‘ ’与“ ”惹的祸。虽然单双引用的作用都禁止特殊字符扩展，' '比“ ”禁止更加严格，在'~'里～只是一个普通字符～;而“~”未被禁止扩展，代表$HOME
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:~$
代码： 全选
] ls -ld //