问题
I've got an extreme problem, and all of the solutions I can imagine are complicated. According to my UNIX/Linux experience there must be an easy way.
I want to delete the first n bytes of file in log.txt.file is long enough. Well, I'm sure somebody will deliver me a suprisingly easy solution I just can't imagine.
回答1:
I am not sure what you want: Your headline says move first N byte to another file, your text says you want to delete the first N bytes
tail -c +N log.txt
Will output everything after the first N bytes, so this will answer you text question. Moving them to another file (as your headline requests) you have to do
head -c N log.txt > other.file
回答2:
What about using tail with it's -c option
from man :
-c, --bytes=K
output the last K bytes; alternatively, use -c +K to output bytes starting with the Kth of each file
so you can do something like tail -c +N log.txt.file
where N is the Number of bytes to delete
Example :
[prompt]$ cat file
ABCDEFGH
[prompt]$ tail -c +2 file //output bytes starting from the second byte
BCDEFGH
[prompt]$ tail -c +3 file //output bytes starting from the third byte
CDEFGH
[prompt]$ tail -c +5 file //output bytes starting from the fifth byte
EFGH
[prompt]$ ls -l
-rw-r--r-- 1 user users 9 2014-08-07 10:22 file // 9 bytes
[prompt]$ tail -c +S file >> file2 //this will copy file content to file2 escaping the first 4 bytes
[prompt]$ ls -l file2
-rw-r--r-- 1 user users 5 2014-08-07 10:29 file2 // 5 bytes (9 - first 4 bytes)
i have to mention that you can use also --bytes option to get the last N bytes from a file.
[prompt]$ tail --bytes=5 file //print the last 5 bytes
EFGH
来源：https://stackoverflow.com/questions/25177284/how-to-move-first-n-bytes-from-text-file-to-another-text-file