bash – 由Cygwin打印不可打印的字符

发布时间：2020-12-15 21:07:25 所属栏目：安全来源：网络整理

导读：Grepping不可打印的字符似乎不适用于回车(控制键^ M). usr@R923047 ~$head -3 test.ctlrow 1row 2row 3usr@R923047 ~$head -3 test.ctl | cat -nv 1 row 1^M 2 row 2^M 3 row 3usr@R923047 ~$head -3 test.ctl | grep '[^[:print:]]'usr@R923047 ~$head -3 t

Grepping不可打印的字符似乎不适用于回车(控制键^ M).

usr@R923047 ~
$head -3 test.ctl
row 1
row 2
row 3
usr@R923047 ~
$head -3 test.ctl | cat -nv
     1  row 1^M
     2  row 2^M
     3  row 3
usr@R923047 ~
$head -3 test.ctl | grep '[^[:print:]]'

usr@R923047 ~
$head -3 test.ctl | grep '[[:cntrl:]]'

usr@R923047 ~

解决方法

根据grep man-page,您可以指定-U或–binary：

Treat the file(s) as binary. By default,under MS-DOS and MS-Windows,grep guesses the file
type by looking at the contents of the first 32KB read from the file. If grep decides the
file is a text file,it strips the CR characters from the original file contents (to make
regular expressions with ^ and $ work correctly). Specifying -U overrules this guesswork,
causing all files to be read and passed to the matching mechanism verbatim; if the file is a
text file with CR/LF pairs at the end of each line,this will cause some regular expressions
to fail. This option has no effect on platforms other than MS-DOS and MS-Windows.

所以：

$head -3 test.ctl
row 1
row 2
row 3
$head -3 test.ctl | cat -nv
     1  row 1^M
     2  row 2^M
     3  row 3
$head -3 test.ctl | grep '[^[:print:]]'

$head -3 test.ctl | grep '[[:cntrl:]]'

$head -3 test.ctl | grep -U '[^[:print:]]'
row 1
row 2

$head -3 test.ctl | grep -U '[[:cntrl:]]'
row 1
row 2

（编辑：李大同）

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