* [BUG?] "git submodule foreach" when command is ssh
@ 2011-01-05 22:32 Chris Packham
2011-01-05 22:50 ` Chris Packham
2011-01-05 23:02 ` Seth Robertson
0 siblings, 2 replies; 5+ messages in thread
From: Chris Packham @ 2011-01-05 22:32 UTC (permalink / raw)
To: GIT
Hi All,
I just noticed something odd with "git submodule foreach". I was
running a script to create a backup of each submodule on a server I
have ssh access to. I was surprised to find that git submodule foreach
stopped silently after the first submodule.
A little debugging and I find that
git submodule foreach 'ssh localhost "ls /"' - stops silently after
the first module (note that the command does produce the expected
listing and there is no error about the command failing).
git submodule foreach 'echo foo' - works as expected
Any thoughts as to whats going on?
---
git version 1.7.3.2
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG?] "git submodule foreach" when command is ssh
2011-01-05 22:32 [BUG?] "git submodule foreach" when command is ssh Chris Packham
@ 2011-01-05 22:50 ` Chris Packham
2011-01-05 23:03 ` Jeff King
2011-01-05 23:02 ` Seth Robertson
1 sibling, 1 reply; 5+ messages in thread
From: Chris Packham @ 2011-01-05 22:50 UTC (permalink / raw)
To: GIT
On Thu, Jan 6, 2011 at 11:32 AM, Chris Packham <judge.packham@gmail.com> wrote:
> Hi All,
>
> I just noticed something odd with "git submodule foreach". I was
> running a script to create a backup of each submodule on a server I
> have ssh access to. I was surprised to find that git submodule foreach
> stopped silently after the first submodule.
>
> A little debugging and I find that
>
> git submodule foreach 'ssh localhost "ls /"' - stops silently after
> the first module (note that the command does produce the expected
> listing and there is no error about the command failing).
>
> git submodule foreach 'echo foo' - works as expected
>
> Any thoughts as to whats going on?
>
> ---
> git version 1.7.3.2
>
Actually this might be a ssh/bash bug (feature?). There is different
behaviour between
find . -maxdepth 1 -type d -a ! -name '\.*' | while read; do echo
$REPLY && ssh localhost ls /; done
and
find . -maxdepth 1 -type d -a ! -name '\.*' | while read; do echo
$REPLY && ls /; done
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG?] "git submodule foreach" when command is ssh
2011-01-05 22:32 [BUG?] "git submodule foreach" when command is ssh Chris Packham
2011-01-05 22:50 ` Chris Packham
@ 2011-01-05 23:02 ` Seth Robertson
1 sibling, 0 replies; 5+ messages in thread
From: Seth Robertson @ 2011-01-05 23:02 UTC (permalink / raw)
To: Chris Packham; +Cc: GIT
In message <AANLkTi=x2i6NvDNRzbszhk-a-z5AYe46-iUBxQsxJJHC@mail.gmail.com>, Chri
s Packham writes:
I just noticed something odd with "git submodule foreach". I was
running a script to create a backup of each submodule on a server I
have ssh access to. I was surprised to find that git submodule foreach
stopped silently after the first submodule.
A little debugging and I find that
git submodule foreach 'ssh localhost "ls /"' - stops silently after
Putting some input redirection will work around the problem.
Presumably some pipe input is going into the ssh accidentally.
git submodule foreach 'ssh localhost "ls /" < /dev/null'
I'll also just take this moment to advertise gitslave
(http://gitslave.sf.net) as an alternate to submodules which may help
(or hinder) you--depending on your workflow. It doesn't suffer from
this particular problem in any case.
-Seth Robertson
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG?] "git submodule foreach" when command is ssh
2011-01-05 22:50 ` Chris Packham
@ 2011-01-05 23:03 ` Jeff King
2011-01-05 23:22 ` Chris Packham
0 siblings, 1 reply; 5+ messages in thread
From: Jeff King @ 2011-01-05 23:03 UTC (permalink / raw)
To: Chris Packham; +Cc: GIT
On Thu, Jan 06, 2011 at 11:50:58AM +1300, Chris Packham wrote:
> Actually this might be a ssh/bash bug (feature?). There is different
> behaviour between
>
> find . -maxdepth 1 -type d -a ! -name '\.*' | while read; do echo
> $REPLY && ssh localhost ls /; done
>
> and
>
> find . -maxdepth 1 -type d -a ! -name '\.*' | while read; do echo
> $REPLY && ls /; done
Ssh will opportunistically eat data on stdin to send to the other side,
even though the command on the other side ("ls" in this case) will never
read it. Because of course ssh has no way of knowing that, and is trying
to be an interactive terminal. So it ends up eating some random amount
of the data you expected to go to the "read" call.
You can use the "-n" option to suppress it. For example:
$ (echo foo; echo bar) |
while read line; do
echo local $line
ssh host "echo remote $line"
done
produces:
local foo
remote foo
but:
$ (echo foo; echo bar) |
while read line; do
echo local $line
ssh -n host "echo remote $line"
done
produces:
local foo
remote foo
local bar
remote bar
which is what you want.
-Peff
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG?] "git submodule foreach" when command is ssh
2011-01-05 23:03 ` Jeff King
@ 2011-01-05 23:22 ` Chris Packham
0 siblings, 0 replies; 5+ messages in thread
From: Chris Packham @ 2011-01-05 23:22 UTC (permalink / raw)
To: Jeff King; +Cc: GIT
On Thu, Jan 6, 2011 at 12:03 PM, Jeff King <peff@peff.net> wrote:
> On Thu, Jan 06, 2011 at 11:50:58AM +1300, Chris Packham wrote:
>
>> Actually this might be a ssh/bash bug (feature?). There is different
>> behaviour between
>>
>> find . -maxdepth 1 -type d -a ! -name '\.*' | while read; do echo
>> $REPLY && ssh localhost ls /; done
>>
>> and
>>
>> find . -maxdepth 1 -type d -a ! -name '\.*' | while read; do echo
>> $REPLY && ls /; done
>
> Ssh will opportunistically eat data on stdin to send to the other side,
> even though the command on the other side ("ls" in this case) will never
> read it. Because of course ssh has no way of knowing that, and is trying
> to be an interactive terminal. So it ends up eating some random amount
> of the data you expected to go to the "read" call.
>
> You can use the "-n" option to suppress it. For example:
>
> $ (echo foo; echo bar) |
> while read line; do
> echo local $line
> ssh host "echo remote $line"
> done
>
> produces:
>
> local foo
> remote foo
>
> but:
>
> $ (echo foo; echo bar) |
> while read line; do
> echo local $line
> ssh -n host "echo remote $line"
> done
>
> produces:
>
> local foo
> remote foo
> local bar
> remote bar
>
> which is what you want.
>
> -Peff
Thanks that makes sense and adding -n to my ssh invocations solves the problem.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-01-05 23:36 UTC | newest]
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2011-01-05 22:32 [BUG?] "git submodule foreach" when command is ssh Chris Packham
2011-01-05 22:50 ` Chris Packham
2011-01-05 23:03 ` Jeff King
2011-01-05 23:22 ` Chris Packham
2011-01-05 23:02 ` Seth Robertson
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