Dual monitors on Ubuntu

I had two monitors for my workstation. One is 22' and the another is 17'. I used the small one as a extend desktop.

Today I get a another 23' monitor to replace the small one. However the resolution of the 23' monitor can't be changed after pluging it in. It always used the resolution matching the 17' one.

Both 'Setting - Display' and 'AMD Catalyst control' can't adjust it as higher resolution.

After some tuning, I found a workaround.

I totally remove all config of small one from /etc/X11/xorg.conf. Then change its resolution in 'AMD Catalyst control', it works!

[tip]ssh key

Setup SSH without password.
a) execute "ssh-keygen -t rsa" under your linux/unix login to get the RSA keys.
(press Enter for all)
You will get 2 files uner ~/.ssh/, id_rsa and id_rsa.pub
b) Put the public key id_rsa.pub to your remote host: ~/.ssh/authorized_keys If the remote host share the same nfs, just try " cat id_rsa.pub >> ~/.ssh/authorized_keys"
* Remember to modify hostname or ip info in ~/.ssh/authorized_keys to "*", so that you can login from any host without password in your NIS domain.
For example:
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA4Ri5J0s1BL/+mR7RfAuDW6FY2P6ILc61Zvw1BdDkvHMFrTzaC/AUMw33H7biAMCXuCleakCuSoV8ZDiGHYs4wOVvet5sDmphkwdiC4xTekdl3dRNvGjMVbvFUta/Y5CiayL6YIu47Ro6Vvu4Mutsrv/13pTlifrEz+NTR/+bzMb9nTniCwiryMyYod3E46b8WvS8yE3WK+tH4BZE8bjiCwdvAzSdPyk/OFNrlBNuF1yewwnxv1roRD3UalT2+7O4kfEG9sMvvBHjuX2l7xlUe3stBftYpigBbwGmmadxjRpNIlk88t5xKcQX6nSu7V8HI3GWPHI0D+ISIlbfU5Sunw== kzhu0@*

[tip]ssh forward

ssh -qTfnN -D LocalPort remotehost

All the added options are for a ssh session that's used for tunneling.

-q :- be very quite, we are acting only as a tunnel.
-T :- Do not allocate a pseudo tty, we are only acting a tunnel.
-f :- move the ssh process to background, as we don't want to interact with this ssh session directly.
-N :- Do not execute remote command.
-n :- redirect standard input to /dev/null.

In addition on a slow line you can gain performance by enabling compression with the -C option.

[tip]Turn off automatically scanning disk when reboot

tune2fs -i 0 -c 0 /dev/sdx

[Debug][tip]How to ignore specified signal when debugging program via gdb

Such as,
(gdb) handle SIGPIPE nostop noprint pass

[HowTo][tip]How to adjust the font size of Notes editor

Close Notes
Double click c:\notes\notes.ini to open it.
Add one new line "Display_font_adjustment=n" after the third line in notes.ini file. "n" is the number.It can be 1or 2 or 3....and the font will be larger with the number increasing.
Launch note

[tip]convert dos format to unix

In vi/vim,

set file format=unix

or dos2unix, unix2dos

[tip]Makefile

Build c/c++ project always need third party library on linux, such as gtk+, glib. Writing their absolute path in Makefile is not flexible way. You can use pkg-config instead of the absolute path. Below is code snippet:

GTK_LIB=$(shell pkg-config --libs gtk+-2.0)
GTK_INC=$(shell pkg-config --cflags gtk+-2.0)

gcc -o yourlibrary.so $(GTK_INC) $(GTK_LIB)