Dan Walsh 61b129d818 --help option and help command should print to stdout not stderr

--help and help are successful commands so output should not go to error.

QE teams have requested this change, also users doing docker help | less
or docker run --help | less would expect this to work.

Usage statement should only be printed when the user asks for it.
Errors should print error message and then suggest the docker COMMAND --help
command to see usage information.

The current behaviour causes the user to have to search for the error message
and sometimes scrolls right off the screen.  For example a error on a
"docker run" command is very difficult to diagnose.

Finally erros should always exit with a non 0 exit code, if the user
makes a CLI error.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)

2014-08-21 15:35:20 -04:00

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% DOCKER(1) Docker User Manuals % Docker Community % JUNE 2014

NAME

docker-save - Save an image to a tar archive (streamed to STDOUT by default)

SYNOPSIS

docker save [--help] [-o|--output[=OUTPUT]] IMAGE

DESCRIPTION

Produces a tarred repository to the standard output stream. Contains all parent layers, and all tags + versions, or specified repo:tag.

Stream to a file instead of STDOUT by using -o.

OPTIONS

--help Print usage statement

-o, --output="" Write to an file, instead of STDOUT

EXAMPLES

Save all fedora repository images to a fedora-all.tar and save the latest fedora image to a fedora-latest.tar:

$ sudo docker save fedora > fedora-all.tar
$ sudo docker save --output=fedora-latest.tar fedora:latest
$ ls -sh fedora-all.tar
721M fedora-all.tar
$ ls -sh fedora-latest.tar
367M fedora-latest.tar

HISTORY

April 2014, Originally compiled by William Henry (whenry at redhat dot com) based on docker.com source material and internal work. June 2014, updated by Sven Dowideit SvenDowideit@home.org.au

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