Gnu/coreutils/split-invocation
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5.3 split
: Split a file into pieces.
split
creates output files containing consecutive or interleaved
sections of input
(standard input if none is given or input
is ‘-
’). Synopsis:
split [option] [input [prefix]]
By default, split
puts 1000 lines of input
(or whatever is
left over for the last section), into each output file.
The output files’ names consist of prefix
(‘x
’ by default)
followed by a group of characters (‘aa
’, ‘ab
’, … by
default), such that concatenating the output files in traditional
sorted order by file name produces the original input file (except
-nr/n
). By default split will initially create files
with two generated suffix characters, and will increase this width by two
when the next most significant position reaches the last character.
(‘yz
’, ‘zaaa
’, ‘zaab
’, …). In this way an arbitrary
number of output files are supported, which sort as described above,
even in the presence of an --additional-suffix
option.
If the -a
option is specified and the output file names are
exhausted, split
reports an error without deleting the
output files that it did create.
The program accepts the following options. Also see Common options.
- ‘
-l lines
’
‘--lines=lines
’ Put
lines
lines ofinput
into each output file. If--separator
is specified, thenlines
determines the number of records.For compatibility
split
also supports an obsolete option syntax-lines
. New scripts should use-l lines
instead.- ‘
-b size
’
‘--bytes=size
’ Put
size
bytes ofinput
into each output file.size
may be, or may be an integer optionally followed by, one of the following multiplicative suffixes:‘b’ => 512 ("blocks") ‘KB’ => 1000 (KiloBytes) ‘K’ => 1024 (KibiBytes) ‘MB’ => 1000*1000 (MegaBytes) ‘M’ => 1024*1024 (MebiBytes) ‘GB’ => 1000*1000*1000 (GigaBytes) ‘G’ => 1024*1024*1024 (GibiBytes)
and so on for ‘
T
’, ‘P
’, ‘E
’, ‘Z
’, and ‘Y
’. Binary prefixes can be used, too: ‘KiB
’=‘K
’, ‘MiB
’=‘M
’, and so on.- ‘
-C size
’
‘--line-bytes=size
’ Put into each output file as many complete lines of
input
as possible without exceedingsize
bytes. Individual lines or records longer thansize
bytes are broken into multiple files.size
has the same format as for the--bytes
option. If--separator
is specified, thenlines
determines the number of records.- ‘
--filter=command
’ With this option, rather than simply writing to each output file, write through a pipe to the specified shell
command
for each output file.command
should use the $FILE environment variable, which is set to a different output file name for each invocation of the command. For example, imagine that you have a 1TiB compressed file that, if uncompressed, would be too large to reside on disk, yet you must split it into individually-compressed pieces of a more manageable size. To do that, you might run this command:xz -dc BIG.xz | split -b200G --filter='xz > $FILE.xz' - big-
Assuming a 10:1 compression ratio, that would create about fifty 20GiB files with names
big-aa.xz
,big-ab.xz
,big-ac.xz
, etc.- ‘
-n chunks
’
‘--number=chunks
’ Split
input
tochunks
output files wherechunks
may be:n generate n files based on current size of input k/n only output kth of n to stdout l/n generate n files without splitting lines or records l/k/n likewise but only output kth of n to stdout r/n like ‘l’ but use round robin distribution r/k/n likewise but only output kth of n to stdout
Any excess bytes remaining after dividing the
input
inton
chunks, are assigned to the last chunk. Any excess bytes appearing after the initial calculation are discarded (except when using ‘r
’ mode).All
n
files are created even if there are fewer thann
lines, or theinput
is truncated.For ‘
l
’ mode, chunks are approximatelyinput
size /n
. Theinput
is partitioned inton
equal sized portions, with the last assigned any excess. If a line starts within a partition it is written completely to the corresponding file. Since lines or records are not split even if they overlap a partition, the files written can be larger or smaller than the partition size, and even empty if a line/record is so long as to completely overlap the partition.For ‘
r
’ mode, the size ofinput
is irrelevant, and so can be a pipe for example.- ‘
-a length
’
‘--suffix-length=length
’ Use suffixes of length
length
. If alength
of 0 is specified, this is the same as if (any previous)-a
was not specified, and thus enables the default behavior, which starts the suffix length at 2, and unless-n
or--numeric-suffixes=from
is specified, will auto increase the length by 2 as required.- ‘
-d
’
‘--numeric-suffixes[=from]
’ Use digits in suffixes rather than lower-case letters. The numerical suffix counts from
from
if specified, 0 otherwise.from
is supported with the long form option, and is used to either set the initial suffix for a single run, or to set the suffix offset for independently split inputs, and consequently the auto suffix length expansion described above is disabled. Therefore you may also want to use option-a
to allow suffixes beyond ‘99
’. Note if option--number
is specified and the number of files is less thanfrom
, a single run is assumed and the minimum suffix length required is automatically determined.- ‘
-x
’
‘--hex-suffixes[=from]
’ Like
--numeric-suffixes
, but use hexadecimal numbers (in lower case).- ‘
--additional-suffix=suffix
’ Append an additional
suffix
to output file names.suffix
must not contain slash.- ‘
-e
’
‘--elide-empty-files
’ Suppress the generation of zero-length output files. This can happen with the
--number
option if a file is (truncated to be) shorter than the number requested, or if a line is so long as to completely span a chunk. The output file sequence numbers, always run consecutively even when this option is specified.- ‘
-t separator
’
‘--separator=separator
’ Use character
separator
as the record separator instead of the default newline character (ASCII LF). To specify ASCII NUL as the separator, use the two-character string ‘\0
’, e.g., ‘split -t '\0'
’.- ‘
-u
’
‘--unbuffered
’ Immediately copy input to output in
--number r/…
mode, which is a much slower mode of operation.- ‘
--verbose
’ Write a diagnostic just before each output file is opened.
An exit status of zero indicates success, and a nonzero value indicates failure.
Here are a few examples to illustrate how the
--number
(-n
) option works:
Notice how, by default, one line may be split onto two or more:
$ seq -w 6 10 > k; split -n3 k; head xa? ==> xaa <== 06 07 ==> xab <== 08 0 ==> xac <== 9 10
Use the "l/" modifier to suppress that:
$ seq -w 6 10 > k; split -nl/3 k; head xa? ==> xaa <== 06 07 ==> xab <== 08 09 ==> xac <== 10
Use the "r/" modifier to distribute lines in a round-robin fashion:
$ seq -w 6 10 > k; split -nr/3 k; head xa? ==> xaa <== 06 09 ==> xab <== 07 10 ==> xac <== 08
You can also extract just the Kth chunk. This extracts and prints just the 7th "chunk" of 33:
$ seq 100 > k; split -nl/7/33 k 20 21 22
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