Scripting

Oneliner to determine directory size

This is a simple oneliner to determine which user has used most diskspace in their /home directory du -sm $(find /home -type d -maxdepth 1 -xdev) | sort -g The result could look something like this … 215 /home/userT 1367 /home/userB 10865 /home/userL 25326 /home/userY 116328 /home/userH 154426 /home/ The numbers to the left is […]

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Photo etc

Color channel swapping in Photoshop

This is a little HOWTO (or tutorial) about swapping/inverting two color channels. I will swap the red and the blue color channel using Adobe Photoshop CS 3 to create a more “normal” looking picture with a blue sky on my infrared photo taken with my Nikon D80 and a Hoya R72 67mm IR-filter. I will […]

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Scripting

Generate a /etc/hosts file from the command line

This is a simple example of how you can populate a /etc/hosts file with 100 IPs and hosts from the command line # N=1; for i in $(seq -w 100); do echo “192.168.99.$N host$i”; P=$(expr $P + 1); done >> /etc/hosts The result file /etc/hosts 192.168.99.201 host001 192.168.99.201 host002 192.168.99.201 host003 192.168.99.201 host004 192.168.99.201 host005 […]

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Linux

Fix slow SSH login

Add the following line if your SSH login takes a long time on your SSH server. File /etc/ssh/sshd_config: UseDNS no Restart the SSH daemon to activate this change.

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Network

Some iptables tricks

Multiport The Multiport extension allows you to specify multiple ports and ranges and makes it possible to create complex rules in one line. Here’s an example of how you can allow SSH, Web, IMAP and X terminal traffic iptables -A INPUT -p tcp -m multiport –dports 22,80,143,6000:6003 -j ACCEPT The alternative to using this rule […]

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