linux:tools: how to edit pdf files

To the Linux Users who need to edit pdf files or figures:
In Linux, you may use pdfedit or xfig etc to edit pdf files, however, they are not good enough. For example, pdfedit is too slow to make users mad ( I am one of victims :-( ). However, you could use an online tool here:

http://www.pdfescape.com

to edit your pdf files. Fast, easy to use...

Linux:shell:command: speed up 'grep'

'grep' is very slow when using it in a UTF-8 mode, specially for a large text file. However, it is fast if using 'C' mode. Use the command 'locale' to check the variable of 'LC_ALL'. Then

export LC_ALL="C"

(from http://tdas.wordpress.com/2008/02/03/speed-up-grep)

I tested it. The "C" mode is faster 50 times than the regular mode!

Linux: how to get cpu and memory information

In linux, look into the files: /proc/cpuinfo and /proc/meminfo to get information about CPU and memory.

Latex: change row color of table

An example here:

\usepackage[table]{xcolor}
(if you use pdflatex and/or beamer, perhaps you need to transit 'table' by
\documentclass[xcolor=table..]{beamer} or you will have an error like:
! LaTeX Error: Option clash for package xcolor.
)

\begin{table}
\centering
\rowcolors{2}{gray!10}{}\tiny
\begin{tabular}{c||cc|cc}\hline\hline
....
\end{tabular}
\caption{...}
\end{table}

Linux: /tmp cleanup frequency

kerberos is working well in my laptop. However, since the temp ticket file krb5*** is stored in /tmp which is cleaned up as reboot, I cannot use kinit -R to renew the ticket-granting ticket even within its renewable life. So what I do is to change /tmp cleanup frequency. How? edit the file:

/etc/default/rcS

and check the default value of "TMPTIME", 0 means cleanup as reboot. TMPTIME=14 means that the files in the directory will be deleted in a frequency of 2 weeks.

ROOT: error: `Bool_t' does not name a type

In ROOT all 'new' types are defined in the file RType.h and if you wanna use those types in your cpp code you must include any head file based on TObject.h because each head file in ROOT includes RType.h or you just directly include it.

Latex: Error: ! LaTeX Error: Too many unprocessed floats.

When using too much floating figures or tables, latex fails to locate those elements, you may counter the error:

! LaTeX Error: Too many unprocessed floats.

. One of solutions is to use the package 'float' and add [H] in your figure environment. Example:

\usepackage{float} %before text body

\begin{figure}[H]
\centering
\includegraphics[width=0.8\textwidth]{fig_tauid/plot_compare_tauprop_allvar_TTauAndTauIDTree_20080814_Tau_dalpha.eps}
\caption{Comparison between different samples used in tau ID study.}
\end{figure}