Linux
因为网络传输的限制,导致很多时候,需要在 Linux 系统下进行大文件的切割。这样将一个大文件切割成为多个小文件,进行传输,传输完毕之后进行合并即可。

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

[1] 命令语法

  1. # -a: 指定输出文件名的后缀长度(默认为2个:aa,ab...)
  2. # -d: 指定输出文件名的后缀用数字代替
  3. # -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)
  4. # -b: 二进制分割模式(支持单位:k/m)
  5. # -C: 文件大小分割模式(切割时尽量维持每行的完整性)
  6. split [-a] [-d] [-l <行数>] [-b <字节>] [-C <字节>] [要切割的文件] [输出文件名]

[2] 使用实例

  1. # 行切割文件
  2. $ split -l 300000 users.sql /data/users_
  3. # 使用数字后缀
  4. $ split -d -l 300000 users.sql /data/users_
  5. # 按字节大小分割
  6. $ split -d -b 100m users.sql /data/users_

[3] 帮助信息

  1. # 帮助信息
  2. $ split --help
  3. Usage: split [OPTION]... [FILE [PREFIX]]
  4. Output pieces of FILE to PREFIXaa, PREFIXab, ...;
  5. default size is 1000 lines, and default PREFIX is 'x'.
  6. With no FILE, or when FILE is -, read standard input.
  7. Mandatory arguments to long options are mandatory for short options too.
  8. -a, --suffix-length=N generate suffixes of length N (default 2) 后缀名称的长度(默认为2)
  9. --additional-suffix=SUFFIX append an additional SUFFIX to file names
  10. -b, --bytes=SIZE put SIZE bytes per output file 每个输出文件的字节大小
  11. -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
  12. -d use numeric suffixes starting at 0, not alphabetic 使用数字后缀代替字母后缀
  13. --numeric-suffixes[=FROM] same as -d, but allow setting the start value
  14. -e, --elide-empty-files do not generate empty output files with '-n' 不产生空的输出文件
  15. --filter=COMMAND write to shell COMMAND; file name is $FILE 写入到shell命令行
  16. -l, --lines=NUMBER put NUMBER lines/records per output file 设定每个输出文件的行数
  17. -n, --number=CHUNKS generate CHUNKS output files; see explanation below 产生chunks文件
  18. -t, --separator=SEP use SEP instead of newline as the record separator; 使用新字符分割
  19. '\0' (zero) specifies the NUL character
  20. -u, --unbuffered immediately copy input to output with '-n r/...' 无需缓存
  21. --verbose print a diagnostic just before each 显示分割进度
  22. output file is opened
  23. --help display this help and exit 显示帮助信息
  24. --version output version information and exit 显示版本信息
  25. The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
  26. Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
  27. CHUNKS may be:
  28. N split into N files based on size of input
  29. K/N output Kth of N to stdout
  30. l/N split into N files without splitting lines/records
  31. l/K/N output Kth of N to stdout without splitting lines/records
  32. r/N like 'l' but use round robin distribution
  33. r/K/N likewise but only output Kth of N to stdout
  34. GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
  35. Full documentation at: <http://www.gnu.org/software/coreutils/split>
  36. 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

[1] 命令语法

  1. # -n: 显示行号
  2. # -e: 以$字符作为每行的结尾
  3. # -t: 显示TAB字符(^I)
  4. cat [-n] [-e] [-t] [输出文件名]

[2] 使用实例

  1. # 合并文件
  2. $ cat /data/users_* > users.sql

[3] 帮助信息

  1. # 帮助信息
  2. $ cat --h
  3. Usage: cat [OPTION]... [FILE]...
  4. Concatenate FILE(s) to standard output.
  5. With no FILE, or when FILE is -, read standard input.
  6. -A, --show-all equivalent to -vET
  7. -b, --number-nonblank number nonempty output lines, overrides -n
  8. -e equivalent to -vE
  9. -E, --show-ends display $ at end of each line
  10. -n, --number number all output lines
  11. -s, --squeeze-blank suppress repeated empty output lines
  12. -t equivalent to -vT
  13. -T, --show-tabs display TAB characters as ^I
  14. -u (ignored)
  15. -v, --show-nonprinting use ^ and M- notation, except for LFD and TAB
  16. --help display this help and exit
  17. --version output version information and exit
  18. Examples:
  19. cat f - g Output f's contents, then standard input, then g's contents.
  20. cat Copy standard input to standard output.
  21. GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
  22. Full documentation at: <http://www.gnu.org/software/coreutils/cat>
  23. or available locally via: info '(coreutils) cat invocation'