Author Archives: yan

ldconfig — change lib path

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Sometimes it’s preferred to install libraries into non-default locations, such as /usr/local/,
but how to let the system know where to find them?

ldconfig can be used to change the lib path,

Ex. To have the system be able to find libraries under /usr/local/lib for myapp

vi /etc/ld.so.conf.d/myapp.conf
/usr/local/lib
#ldconfig

To check result
#ldconfig -v

# ldconfig -l /path/to/lib/missing.lib.so

Great articles about shared libraries.
http://www.cyberciti.biz/faq/linux-setting-changing-library-path/
http://www.cyberciti.biz/tips/linux-shared-library-management.html

Linux Network command –tcpdump

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Examples:

Show details of packets
#tcpdump -nnvvXS

tcpdump

show specific type of connection
#tcpdump icmp/tcp/udp

Add more options with source/destination IP/port, write to file
tcpdump -nnvvXS src 1.2.3.4 and port 3306 -w /tmp/test.pcap

Read tcpdump log from the file
tcpdump -qns -0 A -r /tmp/test.pcap

tcpick -C -yP -r /tmp/test.pcap

ngrep
ngrep -d any -W byline dst 1.2.3.4 > /tmp/test.pcap

Sandstone peak

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[singlepic id=127 w=320 h=240 float=left] The beautiful landscape of the Sandstone peak always reminds me the animation movie “sky castle” of Miyazaki Hayao. Huge boulders emerged out of the green hills, somehow makes me feel I am in a different world.

It was a long drive from the PCH. Shortly after we saw the Circle X Ranch a sign shows up at the entrance of a parking saying “Sandstone peak trail head”.

[singlepic id=115 w=320 h=240 float=left]The trails is called Mishe Mokwa trail. It’s a loop with several peaks next to it. without going up the peaks, it’s pretty flat except the first part. We first hiked up the Sandstone peak. Then Tri peak, big dome. The view from these peaks is very breath taking.

On the way back we saw the famous “balance rock” and “split rock”.

NPR Book about Habits

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A very good article to read or listen on NRP. The author and the book sound very interesting too.
It’s on my reading list.

It’s also talking about how some companies use the study of habits for their marketing strategy.

http://www.npr.org/2012/03/05/147192599/habits-how-they-form-and-how-to-break-them

Hiking at Devils slide

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[singlepic id=107 w=320 h=240 float=left]Stayed at Idylwild for the first night, to get used to the 5000FT escalation.

The next morning, we drove to the Ranger’s office and got a permit to go into the San Jacinto wildness.
It’s required to have the permit and later we did meet a ranger on the trail that checked out permission.

As soon as we started walking on the Deviles slide trail we noticed there’s snow everywhere. It was around 1 food deep snow. Some melted on the trail but still a lot left, especially the trail was in the shadow of the mountain. We put on the snow trac on our shoes so it was not so hard to walk.

When we reached to the saddle junction, the snow there were even more soft. We would need to wear snow shoes to walk around. I decided to return from there. We walked 5 miles and 2400FT escalation gain.
devilslide-5172

SPF for Gmail

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I had a problem that mail sent from one gmail account to another got bounced back. It shows in the bounced mail that there was a softfail happened.

“mydomain” does not designate xxx.xxx.xxx.xxx as permitted sender

and xxx.xxx.xxx.xxx belongs to one of the gmail’s mail server.

It seems that the gmail server sent the email was not recognized as a valid sender…

Then I found this page,

http://support.google.com/a/bin/answer.py?hl=en&answer=60764

It needs to add “include:_spf.google.com” in the SPF!

Install ubuntu to EeePC

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1. Create a USB image to install Ubuntu to EeePC.
problem:
Got error: “Unknown keyword in configuration file”

How to fix:
This page is very helpful
http://alexsleat.co.uk/2010/11/27/how-to-fix-unknown-keyword-in-configuration-file-ubuntu-usb-boot/

2. choose partition
delete old /dev/sda7
then “Add” on “Free Space” -> new /dev/sda7
ext3
mount point -> /
Then install

bg

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To suspend the command just run

Ctrl + Z

Then use bg command to put in the background

Ex.
find / -name “syslog”

>Ctrl + z

[1]+ Stopped find / -name “syslog”

>jobs
[1]+ Stopped find / -name “syslog”

>bg %1
[1]+ find / -name “syslog” &