Unix

Extended Attributes

  • Applications can set these on files…tagged values.
  • ls -l (lower-case 'ell') puts a '@' on the end of the permissions set to indicate there are extended attributes on a file.
  • ls -@ will display the list of extended attributes under a file (and their size).
  • cp -X will exclude extended attributes while copying. By default they are copied.

find/grep

  • exec utility [argument] ; executes once per pathname
  • exec utility [argument] + executes for as many pathnames as possible.

Networking

netstat -rn

sudo route flush (do this four times and the route table to scraped down to bare-bones).
sudo route add default (gateway-ip)
sudo route delete (netmask) (e.g. sudo route delete 10.0.0.0/8)
sudo route delete -host (ip-addr)

Performance Measures

It might be good to run lsof (you'll need to sudo) next time to you see an I/O issue to see if there's another process on that box that may be taxing the disk. You may not find a smoking gun since there's a good chance it's another process on the SAN but it's another data point in your investigation.

Managing Super User Power

/etc/sudoers

$ sudo -l (lower-case "el") — lists what you can sudo.

Troubleshooting Networking Problems

MTR — sudo yum install mtr-gtk;

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