How to split large text file in windows?

Question

I have a log file with size of 2.5 GB. Is there any way to split this file into smaller files using windows command prompt?

Answer 1

you can split using a third party software http://www.hjsplit.org/, for example give yours input that could be upto 9GB and then split, in my case I split 10 MB each

Answer 2

Of course there is! Win CMD can do a lot more than just split text files :)

Split a text file into separate files of 'max' lines each:

Split text file (max lines each):
: Initialize
set input=file.txt
set max=10000

set /a line=1 >nul
set /a file=1 >nul
set out=!file!_%input%
set /a max+=1 >nul

echo Number of lines in %input%:
find /c /v "" < %input%

: Split file
for /f "tokens=* delims=[" %i in ('type "%input%" ^| find /v /n ""') do (

if !line!==%max% (
set /a line=1 >nul
set /a file+=1 >nul
set out=!file!_%input%
echo Writing file: !out!
)

REM Write next file
set a=%i
set a=!a:*]=]!
echo:!a:~1!>>out!
set /a line+=1 >nul
)

If above code hangs or crashes, this example code splits files faster (by writing data to intermediate files instead of keeping everything in memory):

eg. To split a file with 7,600 lines into smaller files of maximum 3000 lines.

1. Generate regexp string/pattern files with set command to be fed to /g flag of findstr

list1.txt

\[[0-9]\]
\[[0-9][0-9]\]
\[[0-9][0-9][0-9]\]
\[[0-2][0-9][0-9][0-9]\]

list2.txt

\[[3-5][0-9][0-9][0-9]\]

list3.txt

\[[6-9][0-9][0-9][0-9]\]

2. Split the file into smaller files:

type "%input%" | find /v /n "" | findstr /b /r /g:list1.txt > file1.txt
type "%input%" | find /v /n "" | findstr /b /r /g:list2.txt > file2.txt
type "%input%" | find /v /n "" | findstr /b /r /g:list3.txt > file3.txt

3. remove prefixed line numbers for each file split:
   eg. for the 1st file:

for /f "tokens=* delims=[" %i in ('type "%cd%\file1.txt"') do (
set a=%i
set a=!a:*]=]!
echo:!a:~1!>>file_1.txt)

Notes:
Works with leading whitespace, blank lines & whitespace lines.

Tested on Win 10 x64 CMD, on 4.4GB text file, 5651982 lines.

Answer 3

If you have installed Git for Windows, you should have Git Bash installed, since that comes with Git.

Use the split command in Git Bash to split a file:

• into files of size 500MB each: split myLargeFile.txt -b 500m

• into files with 10000 lines each: split myLargeFile.txt -l 10000

Tips:

• If you don't have Git/Git Bash, download at https://git-scm.com/download

• If you lost the shortcut to Git Bash, you can run it using C:\Program Files\Git\git-bash.exe

That's it!

---

I always like examples though...

Example:

You can see in this image that the files generated by split are named xaa, xab, xac, etc.

These names are made up of a prefix and a suffix, which you can specify. Since I didn't specify what I want the prefix or suffix to look like, the prefix defaulted to x, and the suffix defaulted to a two-character alphabetical enumeration.

Another Example:

This example demonstrates

• using a filename prefix of MySlice (instead of the default x),
• the -d flag for using numerical suffixes (instead of aa, ab, ac, etc...),
• and the option -a 5 to tell it I want the suffixes to be 5 digits long:

Answer 4

Set Arg = WScript.Arguments
set WshShell = createObject("Wscript.Shell")
Set Inp = WScript.Stdin
Set Outp = Wscript.Stdout
    Set rs = CreateObject("ADODB.Recordset")
    With rs
        .Fields.Append "LineNumber", 4 

        .Fields.Append "Txt", 201, 5000 
        .Open
        LineCount = 0
        Do Until Inp.AtEndOfStream
            LineCount = LineCount + 1
            .AddNew
            .Fields("LineNumber").value = LineCount
            .Fields("Txt").value = Inp.readline
            .UpDate
        Loop

        .Sort = "LineNumber ASC"

        If LCase(Arg(1)) = "t" then
            If LCase(Arg(2)) = "i" then
                .filter = "LineNumber < " & LCase(Arg(3)) + 1
            ElseIf LCase(Arg(2)) = "x" then
                .filter = "LineNumber > " & LCase(Arg(3))
            End If
        ElseIf LCase(Arg(1)) = "b" then
            If LCase(Arg(2)) = "i" then
                .filter = "LineNumber > " & LineCount - LCase(Arg(3))
            ElseIf LCase(Arg(2)) = "x" then
                .filter = "LineNumber < " & LineCount - LCase(Arg(3)) + 1
            End If
        End If

        Do While not .EOF
            Outp.writeline .Fields("Txt").Value

            .MoveNext
        Loop
    End With

Cut

filter cut {t|b} {i|x} NumOfLines

Cuts the number of lines from the top or bottom of file.

t - top of the file
b - bottom of the file
i - include n lines
x - exclude n lines

Example

cscript /nologo filter.vbs cut t i 5 < "%systemroot%\win.ini"

Another way This outputs lines 5001+, adapt for your use. This uses almost no memory.

Do Until Inp.AtEndOfStream
         Count = Count + 1
         If count > 5000 then
            OutP.WriteLine Inp.Readline
         End If
Loop

Answer 5

You can use the command split for this task. For example this command entered into the command prompt

split YourLogFile.txt -b 500m

creates several files with a size of 500 MByte each. This will take several minutes for a file of your size. You can rename the output files (by default called "xaa", "xab",... and so on) to *.txt to open it in the editor of your choice.

Make sure to check the help file for the command. You can also split the log file by number of lines or change the name of your output files.

(tested on Windows 7 64 bit)