Linux 大文件的分割与合并
１．分割 -- split命令
可以指定按行数分割和按字节大小分割两种模式。
(1) 按行数分割
$ split -l 300 large_file.txt new_file_prefix
加上-d，使用数字后缀；加上--verbose，显示分割进度：
$ split -l50000 -d large_file.txt part_ --verbose
(2) 按字节大小分割
$ split -b 10m large_file.log new_file_prefix
２．合并 -- cat命令
$ cat part_* > merge_file.txt
[注] split命令语法：
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$ split --h
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) 后缀名称的长度 (默认为2)
--additional-suffix=SUFFIX append an additional SUFFIX to file names-b, --bytes=SIZE put SIZE bytes per output file 每个输出文件的字节大小
-C, --line-bytes=SIZE put at most SIZE bytes of records per output file 每个输出文件每行的最大字节大小
-d use numeric suffixes starting at 0, not alphabetic 使用数字后缀代替字母后缀
--numeric-suffixes[=FROM] same as -d, but allow setting the start value-e, --elide-empty-files do not generate empty output files with '-n' 不产生空的输出文件
--filter=COMMAND write to shell COMMAND; file name is $FILE 写入到shell命令行-l, --lines=NUMBER put NUMBER lines/records per output file 设定每个输出文件的行数，默认行数是1000行
-n, --number=CHUNKS generate CHUNKS output files; see explanation below 产生chunks文件
-t, --separator=SEP use SEP instead of newline as the record separator; 使用新字符分割
'\0' (zero) specifies the NUL character-u, --unbuffered immediately copy input to output with '-n r/...' 无需缓存
--verbose print a diagnostic just before each 显示分割进度
output file is opened
--help display this help and exit 显示帮助信息
--version output version information and exit 显示版本信息
The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
CHUNKS may be:
N split into N files based on size of input
K/N output Kth of N to stdout
l/N split into N files without splitting lines/records
l/K/N output Kth of N to stdout without splitting lines/records
r/N like 'l' but use round robin distribution
r/K/N likewise but only output Kth of N to stdout
GNU coreutils online help: http://www.gnu.org/software/coreutils/
Full documentation at: http://www.gnu.org/software/coreutils/split
or available locally via: info '(coreutils) split invocation'
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cat命令语法：
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$ cat --h
Usage: cat [OPTION]... [FILE]...
Concatenate FILE(s) to standard output.
With no FILE, or when FILE is -, read standard input.
-A, --show-all equivalent to -vET
-b, --number-nonblank number nonempty output lines, overrides -n
-e equivalent to -vE
-E, --show-ends display $ at end of each line
-n, --number number all output lines
-s, --squeeze-blank suppress repeated empty output lines
-t equivalent to -vT
-T, --show-tabs display TAB characters as ^I
-u (ignored)
-v, --show-nonprinting use ^ and M- notation, except for LFD and TAB
--help display this help and exit
--version output version information and exit
Examples:
cat f - g Output f's contents, then standard input, then g's contents.
cat Copy standard input to standard output.
GNU coreutils online help: http://www.gnu.org/software/coreutils/
Full documentation at: http://www.gnu.org/software/coreutils/cat
or available locally via: info '(coreutils) cat invocation'
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