On 09Apr2017 13:57, Samuel Sieb <samuel@xxxxxxxx> wrote:
On 04/09/2017 07:23 AM, bruce wrote:
the following test works..
ssh user_foo@1.2.3.4 pgrep -f 'master_app' | wc -l
however, i realized that in some cases I was seeing a "ssh connection
timeout" so I looked into how to capture the complete STDERR from the
local side.
ssh user_foo@1.2.3.4 "pgrep -f 'master_app' | wc -l " 1>&2
runs but not sure it will actually do what I want...
commands are very different from each other. The first one will run the "wc
-l" on the local computer and the second one will run it on the remote
computer. The "1>&2" will redirect the stdout to stderr, so all your output
will be coming out in stderr. If you want to include stderr in stdout, use
"2>&1". If you just want to save stderr somewhere, you can use "2>filename".
All very pertinent points. Just to add one:
if you're doing the first command (ssh ... | wc ...) then your redirections
apply only to the "wc". You seem to want the stderr from the ssh. For that you
need to go:
ssh .... 2>filename | wc -l
One reason that you may think the two commands are the same is that
functionally they pretty much are because wc (as invoked) read from stdin and
writes to stdout, and so it doesn't matter whether it runs locally or remote.
As a matter of practive I tend to run as little as possibly remotely, so I
would use your first invocation (remote pgrep, local wc) if there wasn't a
special reason otherwise.
Cheers,
Cameron Simpson <cs@xxxxxxxxxx>
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