Linux下如何实现文件切割

linux下文件分割可以通过split命令来实现，可以指定按行数分割和安大小分割两种模式。Linux下文件合并可以通过cat命令来实现，非常简单

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 ] [-b ] [-C ] [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 --helpUsage: 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 stdoutGNU coreutils online help: Full documentation at: 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 --hUsage: 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 exitExamples: 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: Full documentation at: or available locally via: info '(coreutils) cat invocation'