要用到,来mark一下:
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt
abc
abcd
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt | cut -c 1
a
a
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt | cut -c 2
b
b
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt | cut -c 1-2
ab
ab
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt | cut -c 1-3
abc
abc
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt | cut -c 1-4
abc
abcd
ubuntu@VM-0-15-ubuntu:~/taoge$ cat b.txt | cut -c 1-5
abc
abcd
ubuntu@VM-0-15YiIEKs-ubuntu:~/taoge$ cat b.txt | cut -c 1-6
abc
abcd
ubuntu@VM-0-15-ubuntu:~/taoge$
常常配合awk使用。
cut命令可以按字节,字符,域来截取字串,在某些情况下使用cut,确实很方便,下面简单总结下:
1.按字符截取:(源字串:123:456:789)
1>截取第三个字符:
echo 123:456:789 | cut -c3
3
2>截取第三到第六之间的字符:
echo 123:456:789 | cut -c3-6
3:45
3>截取前三个字符
echo 123:456:789 | cut -c-3
123
4>提取第三个及其后面的所有字符
echo 123:456:789 | cut -c3-
3:456:789
5>提取第三到第六和第八到第十间的字符
echo 123:456:789 | cut -c3-6,8-10
3:45:78
小结下
>>这个“-”比较有意思,
在inx前,表示从字串投开始,
放在inx后,表示从idx开始到字串末尾,
在两个idx之间,表示从idx1到idx2。
>>还有这个“,”可以连接我们选择的不连续的域,
比如要取第1,3,5,7个字符:
echo 123:456:789 | cut -c1,3,5,7
1346
>>对于-b选项应该和-c选项差不多吧,就是单位不同而已(我没有像上面一样测试,只是我的理解)
对于-d选项需要配合着-f选项使用,-d是用来指定分隔符,-f用来指定提取第几个域的内容
echo 123:456:789 | cut -d : -f 3
789
cut比较小巧,在适当的场景下使用效率很高,但是它不支持正则表达式,所以在复杂的情况下还是使用awk或者sed比较好!
[xxx@~]$ cut --help
Usage: cut OPTION... [FILE]...
Print selected parts of lines from each FILE to standard output.
Mandatory arguments to long options are mandatory for short options too.
-b, --bytes=LIST select only these bytes
-c, --characters=LIST select only these characters
-d, --delimiter=DELIM use DELIM instead of TAB for field delimiter
-f, --fields=LIST select only these fields; also print any line
that contains no delimiter character, unless
the -s option is specified
-n (ignored)
--complement complement the set of selected bytes, characters
or fields
-s, --only-delimited do not print lines not containing delimiters
--output-delimiter=STRING use STRING as the output delimiter
the default is to use the input delimiter
--help display this help and exit
--version output version information and exit
Use one, and only one of -b, -c or -f. Each LIST is made up of one
range, or many ranges separated by commas. Selected input is written
in the same order that it is read, and is written exactly once.
Each range is one of:
- N N'th byte, character or field, counted from 1
- N- from N'th byte, character or field, to end of line
- N-M from N'th to M'th (included) byte, character or field
- -M from first to M'th (included) byte, character or field
总结
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