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SIGUSR1

Topics: 
Linux

If there's on thing you can say about Unix, then it's the fact that it keeps on amazing you, even after years of usage. Here's a new gem I recently discovered :

When using dd to copy data between devices, it can take a long time to finish, even when using large block sizes. The dd utility doesn't report status information by default, but when fed a SIGUSR1 signal it will dump the status of the current operation :

$ dd if=/dev/zero of=/tmp/foo bs=512 &
[1] 7749

$ kill -SIGUSR1 7749
1038465+0 records in
1038465+0 records out
554904576 bytes (555 MB) copied, 8.79635 seconds, 63.1 MB/s