How to combine combine images/pdfs on Ubuntu?

1. Ubuntu 12.04 pdf printer
sudo apt-get install cups-pdf

2. Combine images into a pdf file
imagemagick is a command line toolkit to modify image files
sudo apt-get install imagemagick
convert 1.png 2.jpg output.pdf


3. Combine pdfs into a single pdf file
pdfshuffler is a GUI toolkit for your use
sudo apt-get install pdfshuffler
pdfshuffler

Chrome: the World Clock app installs malware with it

I just found that the World Clock app in Chrome installs a malware with it which pops up ads when you browse webpages. The link of the malware is:
 http://intext.nav-links.com

If you want to get rid of the malware, just uninstall the World Clock app.

Xcode: how to add include paths

MAC OS: compile Megam for Moses

Megam is a machine learning tool which can be found at:
http://www.umiacs.umd.edu/~hal/megam/

It is required by the pair-wise ranking optimization (PRO, which is a replacement of MERT) of Moses.
It releases its binary executable version on Linux which can run on most Linux systems, but it does not have a binary executable version for MAC OS. We have to compile it by ourselves.

MAC OS version: 10.8.5
Port version: MacPorts 2.2.1
Megam version: 0.92 (Fifth Release 17 August 2007)
Moses version: 1.0

1. install ocaml using port on MAC OS:
sudo port install ocaml

2. go to the MERT directory of Moses:
cd mosesdecoder-RELEASE-1.0/mert

3. download Megam:
wget http://hal3.name/megam/megam_src.tgz
tar -xzvf megam_src.tgz (creating a directory megam_0.92)
cd megam_0.92

4. change megam's Makefile:
(1) replace "WITHSTR =str.cma -cclib -lstr" with:
WITHSTR =str.cma -cclib -lcamlstr
(2) replace "WITHCLIBS =-I /usr/lib/ocaml/caml" with:
WITHCLIBS =-I /opt/local/lib/ocaml/caml/

5. compile:
make opt

6. link:
cd .. (to mosesdecoder-RELEASE-1.0/mert)
ln -sf megam_0.92/megam.opt megam_i686.opt

Now you can run mert-moses.pl with PRO tuning.

VIM: open file at previous position

add the following to your ~/.vimrc:
set viminfo='10,\"100,:20,%,n~/.viminfo

if it still does not work, the problem is likely to be that the ~/.viminfo does not belong to your account. Use the following command to fix it:
sudo chown YourUserName:YourGroup ~/.viminfo

MAC OS: use GNU tools instead of BSD ones

The default tools of MAC OS are the BSD tools unfortunately, e.g., ls, head, etc.
I would say BSD tools are really less advanced than GNU tools, e.g., you can use "head -n -100" with GNU head, but not with BSD head, and the BSD ls is less colorful than the GNU ls.

How can we use GNU tools instead of BSD ones:

(1) install GNU tools using port:

sudo port install coreutils findutils

(2) append the following line to your ~/.bash_profile

export PATH=/opt/local/libexec/gnubin:$PATH

MAC OS 10.8.5: color your ls command

The default ls command is from BSD, and the default ls command on most Linux systems is from GNU.
The BSD ls can not be very colorful in that we can not color files according to their extension names (its related environment variable is LSCOLORS), while the GNU ls is better in this sense by setting the environment variable LS_COLORS.

I am working on MAC OS 10.8.5, and originally I followed this post to configure my ls, but failed. Finally, I have done some changes to the post to make it work for me. My steps are as follows:
(1) install MAC ports which is a similar tool as apt-get on Ubuntu
(2) install the GNU tools using port:

sudo port install coreutils +with_default_names

which was supposed to override the original BSD ls command with the GNU ls command in the post, but it does not work for me. The installed GNU ls command appears with the name gls.
(3) add the following lines to my ~/.bash_profile:

LS_COLORS='rs=0:di=01;34:ln=01;36:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzma=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.bz2=01;31:*.bz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.axv=01;35:*.anx=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.axa=00;36:*.oga=00;36:*.spx=00;36:*.xspf=00;36:*.sh=01;32:*.log=01;33'; 

export LS_COLORS 

export LS_OPTIONS='--color=auto'

# override the original BSD ls

alias ls='gls $LS_OPTIONS -hF'

alias ll='gls $LS_OPTIONS -lhF'