converting hex/decimal/bianry with bash

put this functions in the ~/.bashrc

# convert a number into decimal format
n2d() {
perl -e "printf \"%d\n\", $@"
}

# convert a number into hex format
n2h() {
perl -e "printf \"0x%X\n\", $@"
}

# convert a number into binary format
n2b() {
perl -e "printf \"0b%b\n\", $@"
}

set default window size and font in gVim

click on
edit>startup settings to edit the vimrc in windows

"set defautl window size
set lines=24
set columns=90
"set default font:size
set guifont=Courier\ New:h14

google C++ coding style

http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml

gen_ctags

# setting
WORKDIR=`pwd`
# get all file list
echo "get all file list"
rm ctags.Uranus ctags.utopia 2>/dev/null
find $WORKDIR/Uranus/ -name '*.[HhCc]' >> ctags.Uranus
find $WORKDIR/Uranus/ -name '*.cc' >> ctags.Uranus
find $WORKDIR/Uranus/ -name '*.cpp' >> ctags.Uranus
find $WORKDIR/utopia/ -name '*.[HhCc]' >> ctags.utopia
find $WORKDIR/utopia/ -name '*.cc' >> ctags.utopia
find $WORKDIR/utopia/ -name '*.cpp' >> ctags.utopia

# remove unwanted files

echo "remove unwanted files"
# Uranus
sed -i /Cus60/d ctags.Uranus
sed -i /eCospro/d ctags.Uranus
sed -i /Trunk/d ctags.Uranus
sed -i /u3/d ctags.Uranus
# utopis
sed -i /u2/d ctags.utopia
sed -i /u3/d ctags.utopia

sed -i /t2/d ctags.utopia
sed -i /t4/d ctags.utopia
sed -i /t7/d ctags.utopia
sed -i /t8/d ctags.utopia
sed -i /t9/d ctags.utopia
sed -i /t11/d ctags.utopia
sed -i /t12/d ctags.utopia
sed -i /t13/d ctags.utopia
sed -i /titania4/d ctags.utopia
sed -i /titania7/d ctags.utopia
sed -i /titania8/d ctags.utopia
sed -i /titania9/d ctags.utopia

sed -i /Janus/d ctags.utopia
sed -i /janus/d ctags.utopia
sed -i /j2/d ctags.utopia

sed -i /s7/d ctags.utopia
sed -i /s7j/d ctags.utopia
sed -i /s7ml/d ctags.utopia
sed -i /s7ld/d ctags.utopia
sed -i /s8/d ctags.utopia

sed -i /maria10/d ctags.utopia
sed -i /prans2/d ctags.utopia

sed -i /r2/d ctags.utopia

# generate tag file
cat ctags.Uranus ctags.utopia > ctags.files
echo "generate tag file"
ctags -L ctags.files
#cscope -b -q -k

# generate file list for Perforce
echo "generate file list for Perforce"
ESCSTR=$(echo "$WORKDIR" | sed -e 's/\//\\\//g')
echo $ESCSTR
echo "sed -e 's/$ESCSTR//g' ctags.files > ctags.p4"
sed -e "s/$ESCSTR//g" ctags.files > ctags.p4

# export global variable
echo "===== IMPORTANT ====="
echo "please export the following variable"
echo "export CTAGFILE=$WORKDIR/tags"

linux dump stace functions

1) dump_stack

vimrc

ab tl Tlist
ab tls TlistSync

where

Tlist is for ctag list
TlistSync is for syncing the ctag navigating window with the current cursor

compound statement expression

http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html


wield stuff only for gcc, but useful

vimrc

syntax on
set nu
set ruler
set hlsearch
set cul
colorscheme evening
set vb
cs add cscope.out
set cscopetag
set foldmethod=marker
set tw=80
set ai
set nojoinspaces
set formatoptions=qtcor

"for C programming
ab #i #include
ab #d #define
ab #e #endif
ab #p #pragma
ab #m Min-Hua Chen

"spell check
ab sc set spell
ab nsc set nospell
"ab #c Author(s): xxx
"\Copyright (c) 2008 xxx
"\Permission to copy, modify, and distribute this program is granted


ab #c Author(s): xxx

autocmd BufReadPost *.c set cin
autocmd BufReadPost *.h set cin
autocmd BufReadPost *.pl set cin
autocmd BufReadPost *.cpp set cin
autocmd BufReadPost *.php set cin
autocmd BufReadPost *.py set si
autocmd BufReadPost *.java set si
autocmd BufReadPost *.java set cino+=j1
autocmd BufReadPost *.java set sw=4

Interesting set intersection by using 'uniq'

I was asked to find the intersection of two IP lists yesterday. I write a simple program with Perl. The program iterates the two lists to find the repeated IPs, which is a O(n^2) algorithm.

foreach $a (@A) {
    foreach $b (@B) {
        if ($a eq $b) {
        ...
        }
    }
}

When I wake up this morning, another way to do this pops onto my mind.

cat file-A | sort | uniq > tmp
cat file-B | sort | uniq >> tmp
cat tmp | sort | uniq -d

Basically, it is a O(nlog(n)) algorithm. (the sort operation).

X forwarding in ssh

To enable X forwarding, try the following command
ssh -X xxx.xxx.xxx.xxx

than we can launch a program with GUI through ssh.

Sometimes it does not work as expected, check the DISPLAY environment variable.

export DISPLAY=:10.0