sed奇怪的结果

文件wk
northwest NW Joel Craig 3.0 .98 3 4
western WE Sharon Kelly 5.3 .97 5 23
southwest SW Chris Foster 2.7 .8 2 18
southern SO May Chin 5.1 .95 4 15
southeast SE Derek Johnson 4.0 .7 4 17
eastern EA Susan Beal 4.4 .84 5 20
northeast NE TJ Nichols 5.1 .94 3 13
north NO Val Shultz 4.5 .89 5 9
central CT Sheri Watson 5.7 .94 5 13

用命令sed 's/ \([A-Z][a-z]*\) \([A-Z][a-z]* \)/ \2 \1/g' wk

怎么会是northwest Joel  NWCraig 3.0 .98 3 4
western Sharon  WEKelly 5.3 .97 5 23
southwest Chris  SWFoster 2.7 .8 2 18
southern May  SOChin 5.1 .95 4 15
southeast Derek  SEJohnson 4.0 .7 4 17
eastern Susan  EABeal 4.4 .84 5 20
northeast TJ  NENichols 5.1 .94 3 13
north Val  NOShultz 4.5 .89 5 9
central Sheri  CTWatson 5.7 .94 5 13呢？
我希望是名字和姓倒过来。　　　　　　
--------------------next---------------------

引用:

-(dearvoid@LinuxEden:Forum)-(~/tmp)-
[$$=3901 $?=0] ; cat wk
northwest NW Joel Craig    3.0 .98 3 4
western   WE Sharon Kelly  5.3 .97 5 23
southwest SW Chris Foster  2.7 .8  2 18
southern  SO May Chin      5.1 .95 4 15
southeast SE Derek Johnson 4.0 .7  4 17
eastern   EA Susan Beal    4.4 .84 5 20
northeast NE TJ Nichols    5.1 .94 3 13
north     NO Val Shultz    4.5 .89 5 9
central   CT Sheri Watson  5.7 .94 5 13
-(dearvoid@LinuxEden:Forum)-(~/tmp)-
[$$=3901 $?=0] ; sed 's/ \([a-zA-Z]\+\) \([a-zA-Z]\+\)\( \+[0-9]\)/ \2 \1\3/' wk
northwest NW Craig Joel    3.0 .98 3 4
western   WE Kelly Sharon  5.3 .97 5 23
southwest SW Foster Chris  2.7 .8  2 18
southern  SO Chin May      5.1 .95 4 15
southeast SE Johnson Derek 4.0 .7  4 17
eastern   EA Beal Susan    4.4 .84 5 20
northeast NE Nichols TJ    5.1 .94 3 13
north     NO Shultz Val    4.5 .89 5 9
central   CT Watson Sheri  5.7 .94 5 13
-(dearvoid@LinuxEden:Forum)-(~/tmp)-
[$$=3901 $?=0] ; bye

--------------------next---------------------