一，uniq干什么用的
文本中的重復(fù)行，基本上不是我們所要的，所以就要去除掉。linux下有其他命令可以去除重復(fù)行，但是我覺(jué)得uniq還是比較方便的一個(gè)。使用uniq的時(shí)候要注意以下二點(diǎn)
1，對(duì)文本操作時(shí)，它一般會(huì)和sort命令進(jìn)行組合使用，因?yàn)閡niq 不會(huì)檢查重復(fù)的行，除非它們是相鄰的行。如果您想先對(duì)輸入排序，使用sort -u。
2，對(duì)文本操作時(shí)，若域中為先空字符(通常包括空格以及制表符)，然后非空字符，域中字符前的空字符將被跳過(guò)
二，uniq參數(shù)說(shuō)明
[zhangy@BlackGhost ~]$ uniq --help
用法：uniq [選項(xiàng)]... [文件]
從輸入文件或者標(biāo)準(zhǔn)輸入中篩選相鄰的匹配行并寫(xiě)入到輸出文件或標(biāo)準(zhǔn)輸出。/p>
p>不附加任何選項(xiàng)時(shí)匹配行將在首次出現(xiàn)處被合并。/p>
p>長(zhǎng)選項(xiàng)必須使用的參數(shù)對(duì)于短選項(xiàng)時(shí)也是必需使用的。
-c, --count //在每行前加上表示相應(yīng)行目出現(xiàn)次數(shù)的前綴編號(hào)
-d, --repeated //只輸出重復(fù)的行
-D, --all-repeated //只輸出重復(fù)的行，不過(guò)有幾行輸出幾行
-f, --skip-fields=N //-f 忽略的段數(shù)，-f 1 忽略第一段
-i, --ignore-case //不區(qū)分大小寫(xiě)
-s, --skip-chars=N //根-f有點(diǎn)像，不過(guò)-s是忽略，后面多少個(gè)字符 -s 5就忽略后面5個(gè)字符
-u, --unique //去除重復(fù)的后，全部顯示出來(lái)，根mysql的distinct功能上有點(diǎn)像
-z, --zero-terminated end lines with 0 byte, not newline
-w, --check-chars=N //對(duì)每行第N 個(gè)字符以后的內(nèi)容不作對(duì)照
--help //顯示此幫助信息并退出
--version //顯示版本信息并退出
其中-z不知道有什么用
三，測(cè)試文本文件uniqtest
this is a test
this is a test
this is a test
i am tank
i love tank
i love tank
this is a test
whom have a try
WhoM have a try
you have a try
i want to abroad
those are good men
we are good men
四，實(shí)例詳解
[zhangy@BlackGhost mytest]$ uniq -c uniqtest
3 this is a test
1 i am tank
2 i love tank
1 this is a test //和第一行是重復(fù)的
1 whom have a try
1 WhoM have a try
1 you have a try
1 i want to abroad
1 those are good men
1 we are good men
從上例子中我們可以看出，uniq的一個(gè)特性，檢查重復(fù)行的時(shí)候，只會(huì)檢查相鄰的行。重復(fù)數(shù)據(jù)，肯定有很多不是相鄰在一起的。
[zhangy@BlackGhost mytest]$ sort uniqtest |uniq -c
1 WhoM have a try
1 i am tank
2 i love tank
1 i want to abroad
4 this is a test
1 those are good men
1 we are good men
1 whom have a try
1 you have a try
這樣就可以解決上個(gè)例子中提到的問(wèn)題
[zhangy@BlackGhost mytest]$ uniq -d -c uniqtest
3 this is a test
2 i love tank
uniq -d 只顯示重復(fù)的行
[zhangy@BlackGhost mytest]$ uniq -D uniqtest
this is a test
this is a test
this is a test
i love tank
i love tank
uniq -D 只顯示重復(fù)的行，并且把重復(fù)幾行都顯示出來(lái)。他不能和-c一起使用
[zhangy@BlackGhost mytest]$ uniq -f 1 -c uniqtest
3 this is a test
1 i am tank
2 i love tank
1 this is a test
2 whom have a try
1 you have a try
1 i want to abroad
2 those are good men //只有一行，顯示二行
在這里those只有一行，顯示的卻是重復(fù)了，這是因?yàn)椋?f 1 忽略了第一列，檢查重復(fù)從第二字段開(kāi)始的。
[zhangy@BlackGhost mytest]$ uniq -i -c uniqtest
3 this is a test
1 i am tank
2 i love tank
1 this is a test
2 whom have a try //一個(gè)大寫(xiě)，一個(gè)小寫(xiě)
1 you have a try
1 i want to abroad
1 those are good men
1 we are good men
檢查的時(shí)候，不區(qū)分大小寫(xiě)
[zhangy@BlackGhost mytest]$ uniq -s 4 -c uniqtest
3 this is a test
1 i am tank
2 i love tank
1 this is a test
3 whom have a try //根上一個(gè)例子有什么不同
1 i want to abroad
1 those are good men
1 we are good men
檢查的時(shí)候，不考慮前4個(gè)字符，這樣whom have a try 就和 you have a try 就一樣了。
[zhangy@BlackGhost mytest]$ uniq -u uniqtest
i am tank
this is a test
whom have a try
WhoM have a try
you have a try
i want to abroad
those are good men
we are good men
去重復(fù)的項(xiàng)，然后全部顯示出來(lái)
[zhangy@BlackGhost mytest]$ uniq -w 2 -c uniqtest
3 this is a test
3 i am tank
1 this is a test
1 whom have a try
1 WhoM have a try
1 you have a try
1 i want to abroad
1 those are good men
1 we are good men
對(duì)每行第2個(gè)字符以后的內(nèi)容不作檢查，所以i am tank 根 i love tank就一樣了。
