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
- # -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]
- [2] 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_
- [3] 帮助信息
- # 帮助信息
- $ 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) 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 $FILE 写入到shell命令行
- -l, --lines=NUMBER put NUMBER lines/records per output file 设定每个输出文件的行数
- -n, --number=CHUNKS generate CHUNKS output files; see explanation below 产生chunks文件
- -t, --separator=SEP use SEP instead of newline as the record separator; 使用新字符分割
- '\0' (zero) specifies the NUL character
- -u, --unbuffered immediately copy input to output with '-n r/...' 无需缓存
- --verbose print a diagnostic just before each 显示分割进度
- output file is opened
- --help display this help and exit 显示帮助信息
- --version output version information and exit 显示版本信息
- The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
- Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
- CHUNKS may be:
- N split into N files based on size of input
- K/N output Kth of N to stdout
- l/N split into N files without splitting lines/records
- l/K/N output Kth of N to stdout without splitting lines/records
- r/N like 'l' but use round robin distribution
- r/K/N likewise but only output Kth of N to stdout
- GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
- Full documentation at: <http://www.gnu.org/software/coreutils/split>
- or available locally via: info '(coreutils) split invocation'
2. 文件合并 - cat
在 Linux 系统下使用 cat 命令进行多个小文件的合并也很方便
- [1] 命令语法
- # -n: 显示行号
- # -e: 以$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]
- [2] 使用实例
- # 合并文件
- $ cat /data/users_* > users.sql
- [3] 帮助信息
- # 帮助信息
- $ 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'
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
