January 2021
Intermediate to advanced
581 pages
15h 7m
Chinese
Content preview from bash shell脚本编程经典实例 （第2版）
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中级
shell
工具
｜
145
“
eRrOr
”这样的也不例外。该选项在查找大小写混合的单词时尤其管用，包括可能在句首
或电子邮件地址中大写的那些单词。
7.4.4
参考
•
man grep
•
man regex
（
Linux
、
Solaris
、
HP-UX
）或
man re_format
（
BSD
、
Mac
），参见有关正则
表达式库的详情
• Jeffrey E. F. Friedl
所著的
Mastering Regular Expressions, 3rd Edition
（
O
’
Reilly
出版）
• 9.5
节
7.5
在管道中进行搜索
7.5.1
问题
你要搜索的文本并不在文件中，而是在某个命令或命令管道的输出中。
7.5.2
解决方案
将输出导入
grep
即可。
some pipeline
|
of commands
| grep
7.5.3
讨论
如果没有提供文件名，
grep
会从标准输入读取。大多数经过良好设计可用于
shell
脚本编
程的实用工具会这么做。这也是它们能够作为
shell
脚本的构建块（
building block
）发挥作
用的原因之一。
如果还想用
grep
搜索上一个命令中的错误信息，那么要确保在管道之前将该命令的错误输
出重定向到标准输出。
gcc bigbadcode.c 2>&1 | grep -i error
此命令尝试编译一些假想的代码。将输出通过管道（
|
）传给
grep
之前，我们先重定向命
令的标准错误到标准输出（
2>&1
），然后由
grep
搜索字符串
error
，不区分其大小写（
-i
）。
对
grep
的结果再执行 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.