is there a way using a batch file to copy the last n lines of a log file into a new text file.
Log file:
line 1 line 2 line 3 line 4 line 5 n = 2
Newfile:
line 4 line 5 
- What have you tried, where are you stuck? Please share your coding attempts; consult this help topic: minimal reproducible exampleaschipfl– aschipfl2018-10-05 11:20:07 +00:00Commented Oct 5, 2018 at 11:20
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1 Answer
You could try the following code:
@echo off set /A "_LAST=2" & rem // (define the number of last lines to keep) for /F %%C in ('^< "test.log" find /C /V ""') do set "COUNT=%%C" set /A "LINES=COUNT-_LAST" if %LINES% gtr 0 (set "SKIP=+%LINES%") else (set "SKIP=") > "test.log.new" more %SKIP% "test.log" This script can handle log files containing empty lines and such with a length of up to 65534 characters. However, the output file must not contain more than 65535 lines. Note, that TABs become expanded to SPACEs.
Or try this:
@echo off set /A "_LAST=2" & rem // (define the number of last lines to keep) for /F %%C in ('^< "test.log" find /C /V ""') do set "COUNT=%%C" set /A "LINES=COUNT-_LAST" if %LINES% gtr 0 (set "SKIP=skip^=%LINES%") else (set "SKIP=") > "test.log.new" ( for /F usebackq^ %SKIP%^ delims^=^ eol^= %%L in ("test.log") do ( echo(%%L ) ) This one has not got a limitation for the number of lines, though the file size must be less than 2 GiB. However, it cannot handle files containing empty lines (as they get lost) and such with a length of more than 8190 characters.
