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I use 7-Zip to compress files inside a batch file like this:

...\right_path\7z a file_to_be_compressed

I got the following output:

7-Zip 4.65  Copyright (c) 1999-2009 Igor Pavlov  2009-02-03

Creating archive

Compressing  file_to_be_compressed

Everything is Ok

Is it possible to disable this output (that is, I don't want anything to be printed)?

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up vote 19 down vote accepted

Just add > NUL: to the end of your command.

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Great, thanks !! – Misha Moroshko Oct 1 '10 at 4:41
What is the colon for? – Peter Mortensen Oct 20 '15 at 23:01
@PeterMortensen: In DOS and Windows console, reserved device names such as NUL can be followed by an optional colon. As far as I know, it performs no actual function, but serves as a visual reminder that it's a device and parallels the use of a colon after a drive letter. – Dennis Williamson Oct 20 '15 at 23:14

It is highly recommended to view status messages in the process. To avoid long messages, display only confirmations:

...\right_path\7z a file_to_be_compressed | findstr /b /r /c:"\<Everything is Ok" /c:"\<Scanning" /c:"\<Creating archive"
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Thanks for the findstr solution! It looks like you can somewhat shorten that call by either omitting /b or both the \r and the \< inside the search strings. I'd go with findstr /b /c:"Everything is Ok" /c:"Scanning" /c:"Creating archive" since you don't need regular expressions (the /r option) here - /b already searches only at the beginning of strings. – Oliver Feb 23 '13 at 9:43
if you want to use status messages to check whether the command succeeded it is better to use return codes (0 for success and others which detail what failed). It is easier in a script to make decisions based on these values than on messages. – WoJ Mar 26 '15 at 8:29
Great answer. I went with ... | findstr /v /b /c:"Compressing " to get rid of the file listing but keep the other status messages. – Duncan Smart May 11 at 19:34

Improving Bruno Dermario answer, I wanted to also report errors and be able to check them manually.

...\right_path\7z a file_to_be_compressed > 7z_log.txt
type 7z_log.txt | findstr /b /c:"Everything is Ok" /c:"Scanning" /c:"Creating archive" /c:"Error"
echo (In case of Error check 7z_log.txt)
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In case PowerShell is an option or somebody could use it, here's what I did, based on the idea of the findstr answer.

& $sevenZipBin a "$archiveFile" * | where {
    $_ -notmatch "^7-Zip " -and `
    $_ -notmatch "^Scanning$" -and `
    $_ -notmatch "^Creating archive " -and `
    $_ -notmatch "^\s*$" -and `
    $_ -notmatch "^Compressing "
if (-not $?)
    # Show some error message and possibly exit

In normal operation, this leaves only the "Everything is Ok" line. Should anything unusual be printed, it remains visible (except for empty lines as they appear so often in regular output).

This is tested for 7z format output. Other archive formats may produce other messages than "Compressing". Extracting will likely also produce different messages. But you can easily adapt the filter to your needs.

A more complex idea would be to redirect all output to a buffer and only print it in case the command returns an error exit code. This is a method that works with all commands that allow redirecting and provide an accurate error exit code.

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