sed -i不能单独使用x11

Question

$ cat my_test.txt  
My test for sed starts here :)  
$ sed -i '1s/^/\hi.../' my_test.txt  
$ cat my_test.txt  
hi...My test for sed starts here :)  
$ sed -i '1s/^/\x11/' my_test.txt  
$ cat my_test.txt  
hi...My test for sed starts here :)  
$ sed -i '1s/^/\x11.../' my_test.txt  
$ cat my_test.txt  
...hi...My test for sed starts here :)   
$ sed -i '1s/^/\x11...x11/' my_test.txt    
$ cat my_test.txt  
...x11...hi...My test for sed starts here :)  

比较strace输出，这里分别为

read(3, "My test for sed starts here :)\n", 32768) = 31  
write(4, "hi...My test for sed starts here"..., 36) = 36  

read(3, "hi...My test for sed starts here"..., 32768) = 36  
write(4, "\21hi...My test for sed starts her"..., 37) = 37  

read(3, "\21hi...My test for sed starts her"..., 32768) = 37  
write(4, "\21...\21hi...My test for sed starts"..., 41) = 41  

read(3, "\21...\21hi...My test for sed starts"..., 32768) = 41  
write(4, "\21...x11\21...\21hi...My test for sed"..., 48) = 48  

Answer 1

\hi前面的反斜杠是不必要的，但没有损坏。

\x11前面的反斜杠表示字符为十六进制0x11或八进制021或 Control-Q ，如读/写跟踪所示。这不是打印字符，因此您看不到cat（您必须使用cat -v才能看到它）。

翻译由GNU sed完成，如Escapes部分所述 - 在这种情况下，它不是shell（Bash）正在进行字符映射。