Difference between revisions of "Linux Tools"

Revision as of 14:08, 17 October 2009

ssh-keygen

To be able to ssh to another machine without needing to type your passwd:

Generate keys: $ ssh-keygen -t rsa -b 1024

Use the default file name and empty pass phrase for password less authentication. This will generate keys in

$ .ssh/id_rsa.pub

Then secure shell copy to another host as authorized_keys

$ scp ~/.ssh/id_rsa.pub <machine name>:~/.ssh/authorized_keys

Instructions copied from: http://pr.willowgarage.com/wiki/GB_ssh-keygen

Additional keys can be named authorized_keys2 and so on.

command line tools: find, sed etc.

The find command is pretty nifty:

1. find all directories whose name does not contain svn
   • find . ! -path "*.svn*" -type d
2. remove .svn folders, e.g. after copying a directory which is a local copy of a subversion repository
   • rm -rvf `find . -name "*.svn"`
3. recursively remove all the .pycs
   • alias rmpyc='rm -vf *.pyc; rm -vf `find . -name *.pyc`'
4. remove the pesky .pycs from the repository
   • svn rm `find . -name "*.pyc"`

So is sed:

1. replace update_path with load_manifest. (-i is doing an in-place replace, I believe)
   • sed -i 's/update_path/load_manifest/' `find . -name "*.py"`

udev for persistent device naming

Steps in brief

• sudo lsusb -v >pre # with device being unplugged
• sudo lsusb -v >post # with device being plugged in
• diff pre post (or use meld for a nicer graphical tool for comparing files) # you can read the Serial Number on the line "iSerial" etc.
• Now edit the udev rules in /etc/udev/rules.d/10-ROBOT.rules
• sudo /etc/init.d/udev restart
• ls /dev/robot -- to check whether the devices appear.

Sample file

Here is a sample 10-ROBOT.rules file that we use on our robot.

BUS=="usb", KERNEL=="ttyUSB*", SYSFS{idVendor}=="0403", SYSFS{idProduct}=="6001", SYSFS{serial}=="A7003N1b", SYMLINK+="robot/servo0"
BUS=="usb", KERNEL=="ttyUSB*", SYSFS{idVendor}=="0403", SYSFS{idProduct}=="6001", SYSFS{serial}=="ftDXR6FS", SYMLINK+="robot/zenither" 

SUBSYSTEMS=="usb", KERNEL=="ttyACM*", PROGRAM="/home/advait/ros/pkgs/ros-pkg-trunk/stacks/laser_drivers/hokuyo_node/bin/getID /dev/ttyACM%n q",  ATTRS{manufacturer}=="Hokuyo Data Flex for USB", ATTRS{product}=="URG-Series USB Driver", SYMLINK+="robot/hokuyo_%c" 

BUS=="usb", SYSFS{idVendor}=="0403", SYSFS{idProduct}=="e729", SYSFS{serial}=="00000215", SYMLINK+="robot/segway_front"
BUS=="usb", SYSFS{idVendor}=="0403", SYSFS{idProduct}=="e729", SYSFS{serial}=="00000201", SYMLINK+="robot/segway_back" 

SUBSYSTEM!="usb", GOTO="robot_rules_end"
ACTION!="add", GOTO="robot_rules_end"
ATTRS{idVendor}=="0403", ATTRS{idProduct}=="e729", MODE="0660", GROUP="plugdev"
LABEL="robot_rules_end"

More information

• http://www.reactivated.net/writing_udev_rules.html#why
• detailed info about writing udev rules: http://www.reactivated.net/writing_udev_rules.html