如何在 Linux下优雅的进行大文件切割与合并
1. 文件切割 - split
在 Linux 系统下使用 split 命令进行大文件切割很方便
[*] 命令语法
[*]# -a: 指定输出文件名的后缀长度(默认为2个:aa,ab...)
[*]# -d: 指定输出文件名的后缀用数字代替
[*]# -l: 行数分割模式(指定每多少行切成一个小文件;默认行数是1000行)
[*]# -b: 二进制分割模式(支持单位:k/m)
[*]# -C: 文件大小分割模式(切割时尽量维持每行的完整性)
[*]split [-a] [-d] [-l <行数>] [-b <字节>] [-C <字节>] [要切割的文件] [输出文件名]
[*] 使用实例
[*]# 行切割文件
[*]$ split -l 300000 users.sql /data/users_
[*]# 使用数字后缀
[*]$ split -d -l 300000 users.sql /data/users_
[*]# 按字节大小分割
[*]$ split -d -b 100m users.sql /data/users_
[*] 帮助信息
[*]# 帮助信息
[*]$ split --help
[*]Usage: split ... ]
[*]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=SUFFIXappend 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-filesdo 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 $FILE 写入到shell命令行
[*]-l, --lines=NUMBER put NUMBER lines/records per output file 设定每个输出文件的行数
[*]-n, --number=CHUNKS generate CHUNKS output files; see explanation below产生chunks文件
[*]-t, --separator=SEP use SEP instead of newline as the record separator;使用新字符分割
[*] '\0' (zero) specifies the NUL character
[*]-u, --unbuffered immediately copy input to output with '-n r/...' 无需缓存
[*] --verbose print a diagnostic just before each 显示分割进度
[*] output file is opened
[*] --help display this help and exit 显示帮助信息
[*] --versionoutput version information and exit 显示版本信息
[*]The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
[*]Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
[*]CHUNKS may be:
[*]N split into N files based on size of input
[*]K/N output Kth of N to stdout
[*]l/N split into N files without splitting lines/records
[*]l/K/N output Kth of N to stdout without splitting lines/records
[*]r/N like 'l' but use round robin distribution
[*]r/K/N likewise but only output Kth of N to stdout
[*]GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
[*]Full documentation at: <http://www.gnu.org/software/coreutils/split>
[*]or available locally via: info '(coreutils) split invocation'
2. 文件合并 - cat
在 Linux 系统下使用 cat 命令进行多个小文件的合并也很方便
[*] 命令语法
[*]# -n: 显示行号
[*]# -e: 以$字符作为每行的结尾
[*]# -t: 显示TAB字符(^I)
[*]cat [-n] [-e] [-t] [输出文件名]
[*] 使用实例
[*]# 合并文件
[*]$ cat /data/users_* > users.sql
[*] 帮助信息
[*]# 帮助信息
[*]$ cat --h
[*]Usage: cat ... ...
[*]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
[*] --versionoutput version information and exit
[*]Examples:
[*]cat f - gOutput 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'
3. 参考文档
[*] Linux 大文件的分割与合并
[*] Linux 学习–文件分割与合并
原文链接：https://mp.weixin.qq.com/s/3f7vfOs-UpEV1bdsVPeCOw
文档来源：服务器之家http://www.zzvips.com/article/170244.html
页:
[1]