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root@E440:/home/zhangsy/opensrc/u-boot-2020.04# split --help
Usage: split [OPTION]... [FILE [PREFIX]]
Output pieces of FILE to PREFIXaa, PREFIXab, ...;
default size is 1000 lines, and default PREFIX is 'x'.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
-a, --suffix-length=N generate suffixes of length N (default 2)
--additional-suffix=SUFFIX append an additional SUFFIX to file names
-b, --bytes=SIZE put SIZE bytes per output file
-C, --line-bytes=SIZE put at most SIZE bytes of records per output file
-d use numeric suffixes starting at 0, not alphabetic
--numeric-suffixes[=FROM] same as -d, but allow setting the start value
-x use hex suffixes starting at 0, not alphabetic
--hex-suffixes[=FROM] same as -x, but allow setting the start value
-e, --elide-empty-files do not generate empty output files with '-n'
--filter=COMMAND write to shell COMMAND; file name is $FILE
-l, --lines=NUMBER put NUMBER lines/records per output file
-n, --number=CHUNKS generate CHUNKS output files; see explanation below
-t, --separator=SEP use SEP instead of newline as the record separator;
' ' (zero) specifies the NUL character
-u, --unbuffered immediately copy input to output with '-n r/...'
--verbose print a diagnostic just before each
output file is opened
--help display this help and exit
--version output version information and exit
The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
CHUNKS may be:
N split into N files based on size of input
K/N output Kth of N to stdout
l/N split into N files without splitting lines/records
l/K/N output Kth of N to stdout without splitting lines/records
r/N like 'l' but use round robin distribution
r/K/N likewise but only output Kth of N to stdout
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/split>
or available locally via: info '(coreutils) split invocation'
使用实例：
1.(按文件大小分割)比如我想将一个log文件切割成每个256k大小，后缀是2位数字结尾的子文件，子文件以child开头，则
split -a 2 -d -b 256k uboot.bin child -a 2 后缀是2位 -d 后缀是数字 -b 256k 每个文件最大256k uboot.bin child 需要切割的文件是uboot.bin，生成的子文件前缀是 "child"
2.（按行数做分割）将一个文件分割成每1万行一个文件，后缀是2位，子文件以child开头
split -a 2 -l 10000 app.log child -a 2 后缀是2位 -l 10000 每10000行一个文件 app.log child 需要切割的文件是app.log，生成的子文件前缀是 "child"