總結
正確的修改進檔案命令(替換檔案內容)：
sed -i "s#machangwei#mcw#g" mcw.txt
正確的修改追加進檔案命令(追加檔案內容)：
sed -i "\$a 8: wo bu hao\!" mcw.txt
sed -i '$a 7: wo hen hao!' mcw.txt
最後一行$a追加內容，加上-i修改到檔案；單引號無需轉義，雙引號需要注意特殊字元轉義
只有-i和替換，沒有-n和列印，才是我們經常需要的替換。將檔案內容替換並寫入到檔案了
第幾行上面插入字串，但是並不修改原檔案，加上-i也不行，使用單雙引號也不行
匹配指定行上面插入或追加字串，會報錯，加上-i不行，不加還是不行，
替換檔案存在的坑
sed -i "s#machangwei#mcw#g" mcw.txt
只有-i和替換，沒有-n和列印，才是我們經常需要的替換。將檔案內容替換並寫入到檔案了。不能新增-n和列印做sed替換
替換實操
首先建立一個測試檔案
[machangwei@mxxx01 ~/mcw]$ mkdir mcw03
[machangwei@mxxx01 ~/mcw]$ cd mcw03/
[machangwei@mxxx01 ~/mcw/mcw03]$ vim mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi machangwei
4: 22bc
5: fff abc
6: abc
[machangwei@mxxx01 ~/mcw/mcw03]$ cp mcw.txt mcw.txt.bak
[machangwei@mxxx01 ~/mcw/mcw03]$ ls
mcw.txt mcw.txt.bak
-n卻沒有列印，不顯示替換結果也不改變檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -n "s#machangwei#mcw#g" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi machangwei
4: 22bc
5: fff abc
6: abc
-n沒有列印，就是空內容，加上-i就把空內容加到檔案裡了。檔案就空了，內容被刪除。sed操作前最好先備份
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -ni "s#machangwei#mcw#g" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$
[machangwei@mxxx01 ~/mcw/mcw03]$ cp mcw.txt.bak mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -ni "s#machangwei#mcw#g" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cp mcw.txt.bak mcw.txt
-n且列印，就顯示替換後的那一行，
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -n "s#machangwei#mcw#gp" mcw.txt
3: wo shi mcw
沒有-n，替換然後列印。替換的行是重複列印
[machangwei@mxxx01 ~/mcw/mcw03]$ sed "s#machangwei#mcw#gp" mcw.txt
1: ni hao ya
2:
3: wo shi mcw
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
-n加列印p,只顯示替換的行，並且顯示是替換後的結果
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -n "s#machangwei#mcw#gp" mcw.txt
3: wo shi mcw
-n加列印p,本來就顯示替換後的行，加個-i修改檔案，那麼把顯示的替換都的行寫入檔案，相當於重寫檔案或者說把顯示結果覆蓋到原檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -ni "s#machangwei#mcw#gp" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
3: wo shi mcw
[machangwei@mxxx01 ~/mcw/mcw03]$ cp mcw.txt mcw.txt.bak
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -n "s#machangwei#mgp" mcw.txt
sed：-e 表示式 #1，字元 16：未終止的“s”命令
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -n "s#machangwei#mcw#gp" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
3: wo shi mcw
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt.bak
3: wo shi mcw
-i插入，後面還有個p列印，會將替換掉的行重複寫入到檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ vim mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ vim mcw.txt.bak
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -n "s#machangwei#mcw#gp" mcw.txt
3: wo shi mcw
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i "s#machangwei#mcw#gp" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt.bak
1: ni hao ya
2:
3: wo shi machangwei
4: 22bc
5: fff abc
6: abc
[machangwei@mxxx01 ~/mcw/mcw03]$ cp mcw.txt.bak mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i "s#machangwei#mcw#gp" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
只有-i和替換，沒有-n和列印，才是我們經常需要的替換。將檔案內容替換並寫入到檔案 了
[machangwei@mxxx01 ~/mcw/mcw03]$ cp mcw.txt.bak mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i "s#machangwei#mcw#g" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
[machangwei@mxxx01 ~/mcw/mcw03]$
[machangwei@mxxx01 ~/mcw/mcw03]$ #上面是替換中存在的坑
追加到檔案最後一行實操
準備檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ #下面是插入和追加到檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
最後一行追加內容，不加-i會顯示追加後的內容，但是不修改檔案。這裡是單引號
[machangwei@mxxx01 ~/mcw/mcw03]$ sed '$a 7: wo hen hao!' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
最後一行追加內容，加上-i修改到檔案。這裡單引號
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i '$a 7: wo hen hao!' mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ sed "\$a 8: wo bu hao!" mcw.txt
-bash: !": event not found
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i '$a 7: wo hen hao\!' mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ vim mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$
雙引號最後一行追加，需要將裡面的特殊字串轉義 。不加-i不修改檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ sed "\$a 8: wo bu hao\!" mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ #雙引號裡特殊字元會被解析，所以要轉義
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
雙引號最後一行追加，需要將裡面的特殊字串轉義 。加-i修改了原檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i "\$a 8: wo bu hao\!" mcw.txt
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ sed "$d" mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
第幾行插入字串，但是並不修改原檔案
[machangwei@mxxx01 ~/mcw/mcw03]$ sed '7i 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
第幾行插入字串，但是並不修改原檔案，加上-i也不行
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i '7i 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
-i 小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ sed '7i 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
-i i 過河
7: wo hen hao!
8: wo bu hao!
第幾行上面插入字串，但是並不修改原檔案，加上-i也不行使用雙引號也不行
[machangwei@mxxx01 ~/mcw/mcw03]$ sed "7i 小馬過河" mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i "7i 小馬過河" mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
-i 小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
匹配指定行上面插入字串，但是並不修改原檔案，加上-i也不行，使用雙引號也不行，
[machangwei@mxxx01 ~/mcw/mcw03]$ sed "/wo he/i 小馬過河" mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
-i/wo he/i馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03sed '/wo he/i 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$
[machangwei@mxxx01 ~/mcw/mcw03]$ sed '/wo he/i 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
匹配指定行上面插入或追加字串，會報錯，加上-i不行，不加還是不行，
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i '/wo he/i 小馬過河' mcw.txt
> ^C
[machangwei@mxxx01 ~/mcw/mcw03]$ sed '/abc/a 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
小馬過河
6: abc
小馬過河
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ sed -i '/abc/a 小馬過河' mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!
[machangwei@mxxx01 ~/mcw/mcw03]$ cat mcw.txt
1: ni hao ya
2:
3: wo shi mcw
4: 22bc
5: fff abc
6: abc
7: wo hen hao!
8: wo bu hao!