| 往往是因爲網絡傳輸的限制，導致很多時候，我們需要在 Linux 系統下進行大文件的切割。這樣將一個大文件切割成爲多個小文件，進行傳輸，傳輸完畢之後進行合併即可。 |
1. 文件切割 - split
在 Linux 系統下使用 split 命令進行大文件切割很方便
[1] 命令語法
# -a: 指定輸出文件名的後綴長度(默認爲2個:aa,ab...) # -d: 指定輸出文件名的後綴用數字代替 # -l: 行數分割模式(指定每多少行切成一個小文件;默認行數是1000行) # -b: 二進制分割模式(支持單位:k/m) # -C: 文件大小分割模式(切割時儘量維持每行的完整性) split [-a] [-d] [-l <行數>] [-b <字節>] [-C <字節>] [要切割的文件] [輸出文件名]
[2] 使用實例
# 行切割文件 $ split -l 300000 users.sql /data/users_ # 使用數字後綴 $ split -d -l 300000 users.sql /data/users_ # 按字節大小分割 $ split -d -b 100m users.sql /data/users_
[3] 幫助信息
# 幫助信息 $ 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) 後綴名稱的長度(默認爲2) --additional-suffix=SUFFIX append an additional SUFFIX to file names -b, --bytes=SIZE put SIZE bytes per output file 每個輸出文件的字節大小 -C, --line-bytes=SIZE put at most SIZE bytes of records per output file 每個輸出文件的最大字節大小 -d use numeric suffixes starting at 0, not alphabetic 使用數字後綴代替字母后綴 --numeric-suffixes[=FROM] same as -d, but allow setting the start value -e, --elide-empty-files do not generate empty output files with '-n' 不產生空的輸出文件 --filter=COMMAND write to shell COMMAND; file name is $FILE 寫入到shell命令行 -l, --lines=NUMBER put NUMBER lines/records per output file 設定每個輸出文件的行數 -n, --number=CHUNKS generate CHUNKS output files; see explanation below 產生chunks文件 -t, --separator=SEP use SEP instead of newline as the record separator; 使用新字符分割 '\0' (zero) specifies the NUL character -u, --unbuffered immediately copy input to output with '-n r/...' 無需緩存 --verbose print a diagnostic just before each 顯示分割進度 output file is opened --help display this help and exit 顯示幫助信息 --version output version information and exit 顯示版本信息 The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000). CHUNKS may be: N split into N files based on size of input K/N output Kth of N to stdout l/N split into N files without splitting lines/records l/K/N output Kth of N to stdout without splitting lines/records r/N like 'l' but use round robin distribution r/K/N likewise but only output Kth of N to stdout GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Full documentation at: <http://www.gnu.org/software/coreutils/split> or available locally via: info '(coreutils) split invocation'
2. 文件合併 - cat
在 Linux 系統下使用 cat 命令進行多個小文件的合併也很方便
[1] 命令語法
# -n: 顯示行號 # -e: 以$字符作爲每行的結尾 # -t: 顯示TAB字符(^I) cat [-n] [-e] [-t] [輸出文件名]
[2] 使用實例
# 合併文件 $ cat /data/users_* > users.sql
[3] 幫助信息
# 幫助信息 $ 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. 參考文檔
- Linux 大文件的分割與合併
- Linux 學習–文件分割與合併