bash - 通过 Cygwin Grepping 不可打印的字符

Question

Grepping 不可打印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 ~

Answer 1

根据 grep 手册页，您可以将 -U 或 --binary 指定为:

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