如何正确操作: grep -ri '->‘

Question

cat a.txt | grep -ri '->'

我想用文本箭头->来grep行。但是在linux shell中，-意味着一个选项的开始。

>表示通过管道输出到文件。

所以在执行了上面给出的命令后，我得到了错误

[root@rs169 document_root]# cat a.txt | grep -ri '->'
grep: invalid option -- '>'
Usage: grep [OPTION]... PATTERN [FILE]...
Try `grep --help' for more information.

有没有人能告诉我怎么做才对？

Answer 1

$ echo "->" | grep -- "->"
->

Answer 2

grep -ri '\->' a.txt应该能做到

[A]$ grep -ri '\->'  a.txt
12 ->2
[A]$ cat a.txt
12 ->2
11

[A]$ sh -version
GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Answer 3

使用-e键显式声明模式：grep -rie '->'

 -e PATTERN, --regexp=PATTERN
          Use PATTERN as the pattern.  This can be used to specify multiple search patterns, or to protect a pattern beginning with a hyphen (-).  (-e is specified by POSIX.)