Re: Problem using dd within bash script

[Bernhard Voelker]

On 04/26/2014 11:46 AM, Pádraig Brady wrote:
> > Everything seems to work fine as long as I am not trying to interrupt
>> this process (using CTRL-C).
> > Only in this case everything just freezes for some time (for about
>> 1 minute the terminal is blocked) [...]
___^^^^^^^^


> dd does catch ^C, but it processes pending interrupts before each read() and 
> write(),
> and those read() and write() calls should return with EINTR.
>
> Therefore it seems like the kernel is blocking these signals?

Hmm, although the kernel may be blocking, it sounds very strange
that the blocking takes one minute. The OP used only bs=4M with
a local file on disk as input file, and an SD card's device as output
file. Even if /dev/sdc was on USB1.1 (12MBit/s), then 4M/minute
sounds very slow. Could it be something else?
Maybe an "strace -tt dd ..." could shed some light on this.

Have a nice day,
Berny