In the case, one want to create one pdf file from N pdf files, gs will save us to do this quickly.

For example,  one has the following pdf files :





And would like to have result.pdf from these pdf files, the following command will create the result.pdf file

gs -q -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=result.pdf -dBATCH file{1..10}.pdf

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posted by citadel

Sometime, one needs to access all attribute on a device in order to create the udev rule for this device.

$ udevadm info --query=all  -n /dev/EtherCAT0 --attribute-walk

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/virtual/EtherCAT/EtherCAT0':

So, based on this output, we can create the udev rules in /etc/udev/rules.d/99-ethercat.rules  as follows:

KERNEL=="EtherCAT*", SUBSYSTEM=="EtherCAT", MODE="0666"

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posted by citadel

Sometime, I would like to get only the mac address of the ethernet device. so here is the command line to do this.

ip addr show dev enp5s0 | grep "link/ether" | awk '{print $2}'

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posted by citadel