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Dircolors

dircolors is something I would like to hate. It is so nice, though. I found some handy workarounds if you find yourself straining to see some of the colors because you, perhaps, opted for a light background color.

There are a few ways to go about this depending on your flavor of system.

First, you will need the existence of a light background dircolor file. Many times this can be found as /etc/DIR_COLORS.lightbgcolor .

One way to get this to work is to set an environment variable

eval `dircolors /etc/DIR_COLORS.lightbgcolor`

Another way to get the behavior, on some flavors of *nix, is to link this file to a dot file in your home directory.

ln -s /etc/DIR_COLORS.lightbgcolor ~/.dir_colors

Resetting file permissions

One of the worst things about NTFS as far as I am concerned is forcing permissions on removable media, when those permissions can so easily be overridden. Here is how to reset the permissions on removable media from windows 7.

  • start up cmd as administrator
  • takeown /f d:\path /r
  • icacls d:\path /reset /T

d:\path is the drive and path to the file or directory you want to reset.

Those attending fart class always try fo

Those attending fart class always try for a passing grade. #joke

ssh speed up

Here is a new one. When ssh slows down put

GSSAPIAuthentication no

into /etc/ssh/ssh_config

 

 

Rescan a scsi bus

Here is the REALLY CRYPTIC way to re-scan a scsi bus in Linux.

echo "- - -" > /sys/class/scsi_host/host0/scan

Have fun with that one.

Logical volumes on LInux

There are some commands that are used to create and manipulate logical volumes.

  • fdisk -c /dev/cciss/c0d1 #partition raw disk
  • parted /dev/sdb #for >= 2TB logical drives
    • mklabel gpt
    • mkpart primary 4096 6000GB
    • toggle 1 lvm
    • quit
  • mkfs /dev/sdb #format to Volume manager disk
    • Select 8e “Linux LVM”
  • pvcreate /dev/sdb /dev/sdc #create a physical volume
  • vgcreate groupname /dev/sdb #give it a group name, add as many PV’s as you need.
  • lvcreate –name lv_name -L size groupname #size is like 200M or 3G, etc.

Other useful commands

  • lvscan #brief listing
  • vgscan
  • lvdisplay #detailed listing
  • vgdisplay
  • lvextend
  • lvreduce
  • lvremove, vgremove, pvremove

You can see some more information here: http://www.howtoforge.com/linux_lvm

qmail tips

I found the following qmail tips to be valuable.

To check the log file:

less /var/log/qmail/imap4/current

Max connections

vi /var/qmail/supervise/imap4/run

Change line with “tcpserver” to have “-c ###” ### of connections.

Count imap connections per IP address

netstat -nt | grep ':143' | awk -F":" '{print $2}' | awk '{print $2}' | sort -n | uniq -c | sort -rn