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Re: How to repeat a bash shell script until success




On 7/15/2017 2:56 AM, Sorin Adrian Savu wrote:
> On Fri, Jul 14, 2017 at 4:06 PM, cyg Simple <cygsimple@xxxxxxxxx> wrote:
>>
>> On 7/14/2017 1:27 AM, Gary Johnson wrote:
>>> On 2017-07-12, Bryan Dunphy wrote:
>>>> I have a shell script, originally created for Mac OS X. that waits
>>>> for an external drive to be mounted (by testing an “ls” of the
>>>> volume’s root directory for success) then runs an “rsync” command.
>>>> How do I get the script to be run repeatedly until successful exit
>>>> under Cygwin?
>>>>
>>>> Here is the unmodified Mac OS version of the script:
>>>>
>>>> #!/bin/bash
>>>> if ls /Volumes/Shared >/dev/null 2>/dev/null
>>>> then
>>>>         rsync -avz --compress-level=9 --delete-during --partial --exclude 'cache/' aleph.gutenberg.org::gutenberg /Volumes/Shared/Project-Gutenberg
>>>>         exit 0
>>>> else
>>>>         exit 1
>>>> fi
>>>
>>> Let the name of your script be "myscript".  The following will run
>>> myscript every two seconds until it succeeds.
>>>
>>>     while ! myscript; do sleep 2; done
>>>
>>> This is really a bash programming question and is not specific to
>>> Cygwin.
>>>
>>
>> In reality the OP script appears to be executed in a crontab system and
>> executed every X minutes.  So a change to the OP question is needed
>> which is answered at[1].  Let's remember some people have no real clue
>> as to what question they should ask and we need to interpret what is
>> being asked into what should have been asked.  If interpretation isn't
>> possible then asking for a use case would be warranted.
>>
>> [1]
>> https://stackoverflow.com/questions/707184/how-do-you-run-a-crontab-in-cygwin-on-windows
> 
> 
> Actually, the correct question would be: how do I run a bash script
> when a USB stick is mounted ?
> 
> Which is doable via Task Scheduler and a event log trigger. See
> https://answers.microsoft.com/en-us/windows/forum/windows_vista-windows_programs/task-scheduler-how-to-automatically-synchronize-my/45a49d83-b1d8-4d37-8896-3d2696cf9795
> on how to locate the appropriate event,
> 
> As for the script:
> 
> - don't use ls for checking file/directory presence use -f/-d (man test)
> - you will need to adjust paths (cygwin has windows drives under
> /cygdrive (cygpath -h)
> 

And don't forget the user has the option to change /cygdrive to
something else including / which is my preference.

> On how to run the script from Task Scheduler use an action like this:
> 
> C:\Tools\cygwin64\bin\bash.exe -c /cygdrive/c/tools/cygwin64/home/bryan/bkp.sh
> (adjust your paths accordingly )

Yes, if you don't want to run cygserver, this is another option.  But if
you're moving from a *nix based system then using cron under cygserver
is what you want.

-- 
cyg Simple

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