[shell基础]——tr命令

(1) tr 字符替换

测试文本内容
# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 loalhost localhost.localdomain localhost6 localhost6.localdomain6

把小写字母替换成大写字母
# tr "[a-z]" "[A-Z]" < /etc/hosts
127.0.0.1 LOCALHOST LOCALHOST.LOCALDOMAIN LOCALHOST4 LOCALHOST4.LOCALDOMAIN4
::1 LOALHOST LOCALHOST.LOCALDOMAIN LOCALHOST6 LOCALHOST6.LOCALDOMAIN6

把：替换成空格
# tr ":" " " < /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
1 loalhost localhost.localdomain localhost6 localhost6.localdomain6

注意这种是3-a、4-b、5-c的一一对应替换方式
# echo 112233445566 | tr "345" "abc"
1122aabbcc66

(2) -s 将连续相同的字符压缩成1个字符

# echo 1122333444555 | tr -s "3"
11223444555

# echo 1122333444555 | tr -s "12345"
12345

去除空行
# cat 1.txt | tr -s "[\n]"

(3) tr -s " " " " 替换且压缩

# cat 5.txt
root tty1 2016-05-22 18:11 (:0)

把空格替换成换行符，并且压缩了(因为原本中间是有多个空格的)
# tr -s " " "\n" <5.txt
root
tty1
2016-05-22
18:11
(:0)

对比一下不压缩的情况
# tr " " "\n" <5.txt
root

tty1

2016-05-22
18:11
(:0)

(4) -d 删除

# cat 1.txt
123And the cowwwwwssssss went homeeeeeeeee
456i havvvvve
789theyyyyyyyyy

删除所有字母
# tr -d "A-z" < 1.txt
123
456
789

tr支持删除 \n\t等字符
# cat 1.txt | tr -d "\n"
And the cowwwwwssssss went homeeeeeeeeei havvvvve theyyyyyyyyy[root@sxjy rh7]#

删除“And”字符
# tr -d [And] < 1.txt
123 the cowwwwwssssss wet homeeeeeeeee
456i havvvvve
789theyyyyyyyyy

删除转换控制字符：
^的八进制代码是136，^M是015，tab键是011，^Z是032
# cat 1.txt | tr -d '[\011\015]'