tr剔除空格冒号

registcn

想删除"a b c "的最后一个空格，
echo \"a b c \"|tr ' "' '"'
得到结果"a"b"c""
本来想得到"a b c"
啥情况

littlecivic

echo \"a b c \"|sed -r 's/(^.*[a-z])(\s+)(\")/\1\3/g'

关阴月飞

回复 1# registcn

1.    echo \"a b c \" |sed 's/ "/"/'

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registcn

谢谢各位，我确实用sed做的，问题是，为啥tr不对呢？rt的结果错在哪里？回复 3# 关阴月飞


   

laliheyi

回复 4# registcn


    tr set1 set2
我的理解是 set1 与 set2 中的 字符是一一对应的，要是set1 比 set2字符数多 set1中多余的字符都是用set2的最后一个字符

rogantianwz

回复 5# laliheyi


    使用 tr 'abc' '012' < yourfile 时 yourfile中的a-->0,b-->1,c-->2

    如果是tr 'abcd' '012' < yourfile ，则是a-->0,b-->1,c-->2,d-->2

所以echo \"a b c \"|tr ' "' '"'   会将空格都替换成双引号 ，双引号也替换成双引号

elu_ligao

空格双引号都替换成双引号了

jeffreyst

tr果然是这样的
使用这样的命令替换：echo \"abc \" | tr ' \"' '2'
结果是这样：2abc22，tr把所有的双引号以及空格都替换成了2，

这个问题，可以使用sed直接将空格删掉就好了，这样比较简单： echo \"abc \" | sed 's/ //'

laliheyi

回复 1# registcn

tr版本

1. tr (GNU coreutils) 5.93
   
2. Copyright (C) 2005 Free Software Foundation, Inc.
   
3. This is free software.  You may redistribute copies of it under the terms of
   
4. the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
   
5. There is NO WARRANTY, to the extent permitted by law.
   
6. 
   
7. Written by Jim Meyering.

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tr帮助中的一段话

1. When `tr' is performing translation, SET1 and SET2 typically have
   
2. the same length.  If SET1 is shorter than SET2, the extra characters at
   
3. the end of SET2 are ignored.
   
4. 
   
5.    On the other hand, making SET1 longer than SET2 is not portable;
   
6. POSIX says that the result is undefined.  In this situation, BSD `tr'
   
7. pads SET2 to the length of SET1 by repeating the last character of SET2
   
8. as many times as necessary.  System V `tr' truncates SET1 to the length
   
9. of SET2.
   
10.    By default, GNU `tr' handles this case like BSD `tr'.  When the
    
11. `--truncate-set1' (`-t') option is given, GNU `tr' handles this case
    
12. like the System V `tr' instead.  This option is ignored for operations
    
13. other than translation.

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