Linux文件分割与合并

Linux里面提供了，许多简洁的shell命令，而这些命令不仅简洁，而且作用十分强大，散仙今天要与大家分享的是关于在linux里面如何拆分，分割文件，和如何合并文件，当然在文章末，还会记录一下，另外几个有用的命令。

关于文件分割最有用的命令就是split命令了，下面看下split的用法：

NAME
       split - split a file into pieces

SYNOPSIS
       split [OPTION]... [INPUT [PREFIX]]

DESCRIPTION
       Output  fixed-size  pieces of INPUT to PREFIXaa, PREFIXab, ...; default size is 1000 lines, and default PREFIX is ‘x’.  With no INPUT, or when INPUT is
       -, read standard input.

       Mandatory arguments to long options are mandatory for short options too.

       -a, --suffix-length=N
              use suffixes of length N (default 2)

       -b, --bytes=SIZE
              put SIZE bytes per output file

       -C, --line-bytes=SIZE
              put at most SIZE bytes of lines per output file

       -d, --numeric-suffixes
              use numeric suffixes instead of alphabetic

       -l, --lines=NUMBER
              put NUMBER lines per output file

       --verbose
              print a diagnostic just before each output file is opened

       --help display this help and exit

       --version
              output version information and exit

       SIZE may be (or may be an integer optionally followed by) one of following: KB 1000, K 1024, MB 1000*1000, M 1024*1024, and so on for G, T, P, E, Z, Y.

AUTHOR
       Written by Torbjorn Granlund and Richard M. Stallman.

REPORTING BUGS
       Report split bugs to [e-mail]
       GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
       General help using GNU software: <http://www.gnu.org/gethelp/>
       Report split translation bugs to <http://translationproject.org/team/>

COPYRIGHT
       Copyright © 2010 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       The full documentation for split is maintained as a Texinfo manual.  If the info and split programs are properly installed at your site, the command

:

（1）按行数切分：split -l 2000 要分割的文件  子文件的前缀
（2）按大小切分: split -b 20m  要分割的文件  子文件的前缀
（3）split -l 2482 ../BLM/BLM.txt -d -a 4 BLM_

将 文件 BLM.txt 分成若干个小文件，每个文件2482行(-l 2482)，文件前缀为BLM_ ，系数不是字母而是数字（-d），后缀系数为四位数（-a 4）



上面说的分割，下面我们来看下如何合并多个文件，如果是比较重要的大文件或数据文件，在分割的时候，可以作md5校验和，在合并时重新校验数据，如果发现不一致，则是传输损坏等情况造成，可重新传输：

[search@h1 823]$ md5sum a.txt 
2dbf68d4aba8dbe6a485293f8464be64  a.txt
[search@h1 823]$ 

使用cat命令进行合并：
cat *.txt >> total.txt




最后记录一下，几个比较有用的命令，对一个日志文件中的ip地址，去重，统计，排序，怎么做？

cat test.txt|awk '{print $1}'|sort|uniq -c