How can I split a large text file into smaller files with an equal number of lines?

Have a look at the split command:

$ split --help
Usage: split [OPTION] [INPUT [PREFIX]]
Output fixed-size pieces of INPUT to PREFIXaa, PREFIXab, ...; default
size is 1000 lines, and default PREFIX is `x'.  With no INPUT, or when INPUT
is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -a, --suffix-length=N   use suffixes of length N (default 2)
  -b, --bytes=SIZE        put SIZE bytes per output file
  -C, --line-bytes=SIZE   put at most SIZE bytes of lines per output file
  -d, --numeric-suffixes  use numeric suffixes instead of alphabetic
  -l, --lines=NUMBER      put NUMBER lines per output file
      --verbose           print a diagnostic to standard error just
                            before each output file is opened
      --help     display this help and exit
      --version  output version information and exit

You could do something like this:

split -l 200000 filename

which will create files each with 200000 lines named xaa xab xac ...

Another option, split by size of output file (still splits on line breaks):

 split -C 20m --numeric-suffixes input_filename output_prefix

creates files like output_prefix01 output_prefix02 output_prefix03 ... each of maximum size 20 megabytes.

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Use the split command:

split -l 200000 mybigfile.txt

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Yes, there is a split command. It will split a file by lines or bytes.

$ split --help
Usage: split [OPTION]... [INPUT [PREFIX]]
Output fixed-size pieces of INPUT to PREFIXaa, PREFIXab, ...; default
size is 1000 lines, and default PREFIX is `x'.  With no INPUT, or when INPUT
is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -a, --suffix-length=N   use suffixes of length N (default 2)
  -b, --bytes=SIZE        put SIZE bytes per output file
  -C, --line-bytes=SIZE   put at most SIZE bytes of lines per output file
  -d, --numeric-suffixes  use numeric suffixes instead of alphabetic
  -l, --lines=NUMBER      put NUMBER lines per output file
      --verbose           print a diagnostic just before each
                            output file is opened
      --help     display this help and exit
      --version  output version information and exit

SIZE may have a multiplier suffix:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.

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Split the file "file.txt" into 10,000-lines files:

split -l 10000 file.txt

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Use split:

Split a file into fixed-size pieces, creates output files containing consecutive sections of INPUT (standard input if none is given or INPUT is `-')

Syntax split [options] [INPUT [PREFIX]]

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Use:

sed -n '1,100p' filename > output.txt

Here, 1 and 100 are the line numbers which you will capture in output.txt.

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split (from GNU coreutils, since version 8.8 from 2010-12-22) includes the following parameter:

-n, --number=CHUNKS     generate CHUNKS output files; see explanation below

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

Thus, split -n 4 input output. will generate four files (output.a{a,b,c,d}) with the same amount of bytes, but lines might be broken in the middle.

If we want to preserve full lines (i.e. split by lines), then this should work:

split -n l/4 input output.

Related answer: https://stackoverflow.com/a/19031247

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You can also use AWK:

awk -vc=1 'NR%200000==0{++c}{print $0 > c".txt"}' largefile

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In case you just want to split by x number of lines each file, the given answers about split are OK. But, I am curious about why no one paid attention to the requirements:

"without having to count them" -> using wc + cut

"having the remainder in extra file" -> split does by default

I can't do that without "wc + cut", but I'm using that:

split -l  $(expr `wc $filename | cut -d ' ' -f3` / $chunks) $filename

This can be easily added to your .bashrc file functions, so you can just invoke it, passing the filename and chunks:

 split -l  $(expr `wc $1 | cut -d ' ' -f3` / $2) $1

In case you want just x chunks without remainder in the extra file, just adapt the formula to sum it (chunks - 1) on each file. I do use this approach because usually I just want x number of files rather than x lines per file:

split -l  $(expr `wc $1 | cut -d ' ' -f3` / $2 + `expr $2 - 1`) $1

You can add that to a script and call it your "ninja way", because if nothing suites your needs, you can build it :-)

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To split a large text file into smaller files of 1000 lines each:

split <file> -l 1000

To split a large binary file into smaller files of 10M each:

split <file> -b 10M

To consolidate split files into a single file:

cat x* > <file>

Split a file, each split having 10 lines (except the last split):

split -l 10 filename

Split a file into 5 files. File is split such that each split has same size (except the last split):

split -n 5 filename

Split a file with 512 bytes in each split (except the last split; use 512k for kilobytes and 512m for megabytes):

split -b 512 filename

Split a file with at most 512 bytes in each split without breaking lines:

split -C 512 filename

--> by : cht.sh

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HDFS getmerge small file and split into a proper size.

This method will cause line breaks:

split -b 125m compact.file -d -a 3 compact_prefix

I try to getmerge and split into about 128 MB for every file.

# Split into 128 MB, and judge sizeunit is M or G. Please test before use.

begainsize=`hdfs dfs -du -s -h /externaldata/$table_name/$date/ | awk '{ print $1}' `
sizeunit=`hdfs dfs -du -s -h /externaldata/$table_name/$date/ | awk '{ print $2}' `
if [ $sizeunit = "G" ];then
    res=$(printf "%.f" `echo "scale=5;$begainsize*8 "|bc`)
else
    res=$(printf "%.f" `echo "scale=5;$begainsize/128 "|bc`)  # Celling ref http://blog.csdn.net/naiveloafer/article/details/8783518
fi
echo $res
# Split into $res files with a number suffix. Ref:  http://blog.csdn.net/microzone/article/details/52839598
compact_file_name=$compact_file"_"
echo "compact_file_name: "$compact_file_name
split -n l/$res $basedir/$compact_file -d -a 3 $basedir/${compact_file_name}

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