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