-bs (Set output stream for output/error/progress line) switch

Syntax

-bs{o|e|p}{0|1|2}

{id}	Stream Type
o	standard output messages
e	error messages
p	progress information

{N}	Stream Destination
0	disable stream
1	redirect to stdout stream
2	redirect to stderr stream

Default values: o1, e2, p1.

Examples

7z t a.7z -bse1 > messages.txt

tests a.7z archive and sends error messages to stdout that is redirected to messages.txt

7z a -si -so -bsp2 -txz -an < file.tar > file.tar.xz

compresses file.tar (from stdin) to file.tar.xz (stdout stream) and shows progress information in stderr stream that can be seen at console window.

Commands that can be used with this switch

a (Add), d (Delete), h (Hash), l (List), e (Extract), u (Update), x (Extract with full paths)

Notes from this site

Not part of the 7-Zip manual. Written by this site; examples checked with 7-Zip 26.04.

What is the exact -bs syntax?

This page documents -bso, -bse and -bsp (the vendor heading calls it -bs). Plain -bs is not valid: pick a stream letter and a number, such as -bso1, -bse2 or -bsp0, and combine several on one command line.

Which switches do I need?

Goal	Add
Silent, but errors still shown	`-bso0 -bsp0`
Fully silent (check the exit code)	`-bso0 -bsp0 -bse0`
Errors only, in a file	`-bso0 -bsp0 2> errors.txt`
Normal messages only, in a file	`-bsp0 > log.txt`

-bso0 alone does not switch off percent progress; that is the separate -bsp stream. The listed switch -bd also disables the progress indicator.

Quick examples

Use 7z on Windows and 7zz (the official console binary) on Linux/macOS.

7z a a.7z folder -bso0 -bsp0
7z t a.7z -bso0 -bsp0 || echo failed
7z x a.7z -bso1 -bsp0 > log.txt
7z a a.7z folder -bso0 -bsp0 2> errors.txt
7z a a.7z folder -bso0 -bsp0 > all.txt 2>&1
7z a -si -so -bsp2 -txz -an < file.tar > file.tar.xz

Line 2 reports a non-zero exit code, so a script knows the test failed (the || form works in Linux/macOS shells and in Windows cmd). Line 5 puts both streams into one file; 2> and 2>&1 work in cmd too. Line 6 is the vendor example: the archive goes to stdout, the percent progress goes to stderr, so the two do not mix.

Good to know

With -bso0 -bsp0 errors are still printed and the exit code still reports problems (see exit codes). With -bse0 too, the messages are hidden but the exit code stays non-zero, so check it in scripts.
When output is redirected to a file, no percent progress is written by default; -bsp1 forces it into the file.
To list processed file names in the log, add -bb. It writes to the output stream, so -bso0 silences it.

-bb, Exit codes, -so