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Rabarberski
Rabarberski

Reputation: 24922

How to suppress specific lines in Windows cmd output?

On Windows, I have written a simple bat script that calls another tool. However, this tool outputs a few specific debug lines when using certain options (seems to be a bug in the original code, which I can not/don't want to modify).

Is there a way to suppress lines output by a command that matches a certain pattern (like starting with DEBUG: )?

(FYIO: the tool is latexdiff.exe, and there are some print STDERR "DEBUG:... lines in the perl source code that are not conditional to the debug variable and printed everytime the --flatten option is used. I don't want to suppress stderr completely either.)

Upvotes: 2

Views: 5501

Answers (1)

Christian.K
Christian.K

Reputation: 49260

You could try the following:

latexdiff.exe 2>&1| findstr /v /b "DEBUG:"

The /v option basically turns the pattern around, i.e. findstr.exe will let everything through, not matching the pattern. The /b option simply says that the pattern should occur at the beginning of a line.

The 2>&1 redirects STDERR to STDOUT and is required because, as you said, the lines are written to STDERR, not STDOUT. Note that as a "side effect" all output now is written to STDOUT.

Update if there is other output on STDOUT that you need to have, you could do something like this

latexdiff.exe old.tex new.tex > diff.tex 2> latexdiff.stderr
type latexdiff.stderr | findstr /v /b "DEBUG:"

That is, redirect STDOUT to your diff file, redirect STDERR to some file. Afterwards, you just type the file to see error messages.

You might want to put that into a batch file of it's own, like so:

@echo off
setlocal
REM determine a suitable temporary filename
set error_file=%TEMP%\latexdiff.%RANDOM%.stderr
REM run actual diff and save its exit code for later
latexdiff.exe "%~1" "%~2" > "%~3" 2> "%error_file%"
set error_level=%ERRORLEVEL%
REM dump error messages
type "%error_file%" | findstr /v /b "DEBUG:"
REM remove temporary error file and exit with latexdiff's exit code.
del /q "%error_file%"
exit /b %error_level%

You can then call it like: latexdiff_wrapper.cmd old.tex new.tex diff.tex. Appart from using temporary files, the downside is, that error messages will not appear while processing, but at the very end. If that is not an issue, it shouldn't because the diff should be fast, you might find that solution useful.

Upvotes: 4

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