CSMA/CD v.s. CSMA/CA

http://www.msservermag.com.tw/technicwords/040422.aspx

Blueprints involving Ubuntu Mobile and Embedded developers

https://blueprints.launchpad.net/~ubuntu-mobile

makefile example

ROOTDIR = ..
include $(ROOTDIR)/config/linux.mak

MODULE = XMLTool
MODULE_LIB = xmltool

ifdef BUILD_SO
ifeq ($(BUILD_SO), true)
LIBNAME = lib$(MODULE_LIB).so
CFLAGS += -fPIC
LFLAGS = -shared -Wl,-soname,$(LIBNAME)
else
LIBNAME = lib$(MODULE_LIB).a
endif
endif

DEPENDENT_MODULES = $(ROOTDIR)/Locker

CFLAGS += -I$(ROOTDIR)/$(MODULE)/include
CFLAGS += `xml2-config --cflags`
CFLAGS += -I$(ROOTDIR)/Locker/include
LDFLAGS += -L$(ROOTDIR)/$(MODULE)/lib -L$(ROOTDIR)/$(MODULE)/release/
LDFLAGS += -L$(DEPENDENT_MODULES)/release/
LDFLAGS += -lstdc++ -lpthread -luuid -llocker
LDFLAGS += `xml2-config --libs`


OBJS += XML.o

MAIN_OBJ =
EXE =

OBJS_SRC = $(addprefix src/,$(OBJS))
MAIN_OBJ_SRC = $(addprefix src/,$(MAIN_OBJ))
LIBNAME_RELEASE = $(addprefix release/,$(LIBNAME))
EXE_RELEASE = $(addprefix release/,$(EXE))

TEST_OBJ = test.o
TEST_EXE = test/test
TEST_OBJ_TST = $(addprefix test/,$(TEST_OBJ))

all: dependent_module $(LIBNAME_RELEASE) $(EXE_RELEASE) $(TEST_EXE)
        @echo "Please export LD_LIBRARY_PATH..."
        @echo "e.g. export LD_LIBRARY_PATH=`pwd`/release"


dependent_module:
        @for modules in $(DEPENDENT_MODULES); do \
          make -C $$modules; \
        done;

$(LIBNAME_RELEASE): $(OBJS_SRC)
        @if [ "$$BUILD_SO" == "true" ]; then \
          $(LINK) $(LFLAGS) -o $(LIBNAME_RELEASE) $^ ;\
        else \
          $(LD) -r -o $(LIBNAME_RELEASE) $^ ;\
        fi

$(EXE_RELEASE): $(LIBNAME_RELEASE) $(MAIN_OBJ_SRC)
        $(C++) -o $@ $(MAIN_OBJ_SRC) $(LDFLAGS) -l$(MODULE_LIB)

$(TEST_EXE): $(LIBNAME_RELEASE) $(TEST_OBJ_TST)
        $(CC) -o $@ $(TEST_OBJ_TST) $(LDFLAGS) -l$(MODULE_LIB)

.cpp.o:
        $(C++) -c $< -o $(patsubst %.cpp,%.o,$<) $(CFLAGS)

.c.o:
        $(CC) -c $< -o $(patsubst %.cpp,%.o,$<) $(CFLAGS)

clean:
        $(RM) $(LIBNAME_RELEASE) $(EXE_RELEASE) $(OBJS_SRC) $(MAIN_OBJ_SRC)
        $(RM) $(TEST_OBJ_TST) $(TEST_EXE) test/output*

makefile, go to each modules

MODULES += UMDToday

all:
@for modules in $(MODULES); do \
make -C $$modules; \
cp -rf ./$$modules/release/* ./release; \
done;

clean:
@for modules in $(MODULES); do \
make clean -C $$modules; \
done;

set environment variable to the command

[will@localhost config]$ cat sendmail.sh
#!/bin/sh

LIST="a b c d e"

for list in $LIST; do\

cat /home/will/log.txt | LD_LIBRARY_PATH=/usr/local/lib /home/will/smtpsend $list > /dev/null 2>&1; \
done;

find with exec

find tmp/ -name ".svn" -exec rm -rf {} \;


find tmp/ -name "a" -exec ls {} \;

my indent coding style

[will@localhost config]$ cat indent.sh
# Will.20070509: linux coding style
dos2unix $*
indent -nbad -bap -nbc -bbo -br -bli2 -bls -ncdb -nce -cp1 -cs -di2 -ndj -nfc1 -nfca -hnl -i2 -ip5 -lp -pcs -psl -nsc -nsob -l100 $*
[will@localhost config]$

use shared library during runtime

[will@localhost DynamicLibrary]$ cat dl.test.c
#include <dlfcn.h>

#include <stdio.h>

main ()

{

void *libc;

void (*printf_call) ();

if (libc = dlopen ("/lib/libc.so.6", RTLD_LAZY))
{

      printf_call = dlsym (libc, "printf");
      (*printf_call) ("hello, world\n");

}

dlclose (libc);

}

[will@localhost DynamicLibrary]$

Make Dynamic Shared Library

gcc -fPIC -c mylib.*.c
gcc -shared -Wl,-soname,libxxx.so -o libxxx.so *.o

Make a Static Library

gcc -c mylib.*
ar rcs mylib.a *.o
gcc xxx.c mylib.a

shell script : while loop

[will@localhost ShellScript]$ cat while.sh
#!/bin/sh

s=0

i=0

while [ "$i" != "10" ]

do

        i=$(($i+1))
        s=$(($s+$i))

done

echo "The result of '1+2+3+...+10' is ==> $s"

[will@localhost ShellScript]$

shell script : test file type

[will@localhost ShellScript]$ cat testfile.sh
#!/bin/sh

read -p "Input a filename : " filename

test -z $filename && echo "You MUST input a filename." && exit 0

test ! -e $filename && echo "The filename $filename DO NOT exist" && exit 0

test -f $filename && filetype="regulare file"
test -d $filename && filetype="directory"
test -r $filename && perm="r"

test -w $filename && perm=$perm"w"

test -x $filename && perm=$perm"x"

echo "The filename: $filename is a $filetype"
echo "And the permission are : $perm"

[will@localhost ShellScript]$

shell script : awk and sort

[will@localhost ShellScript]$ cat sort.sh
#!/bin/sh

ls -l *.sh| awk '{print $8" "$9}'|sort

[will@localhost ShellScript]$

shell script : read line

[will@localhost ShellScript]$ cat read.sh
#!/bin/sh

read -p "Please input your first name: " firstname
read -p "Please input your last name: " lastname
echo -e "Your full name is : "$firstname" "$lastname"\r\n"
[will@localhost ShellScript]$

shell script : execute with parameter

[will@localhost ShellScript]$ cat parameter.sh
#!/bin/sh

echo "The script name is ==> $0"

[ -n "$1" ] && echo "The 1st paramter is ==> $1" || exit 0
[ -n "$2" ] && echo "The 2nd paramter is ==> $2" || exit 0
[ -n "$3" ] && echo "The 3th paramter is ==> $3" || exit 0

echo "integer compare..."

[ "$1" -gt "$2" ] && echo $1" > "$2

[ "$1" -lt "$2" ] && echo $1" < "$2

[ "$1" -eq "$2" ] && echo $1" = "$2

echo "string compare..."

[ "$1" = "$2" ] && echo $1" = "$2

[ "$1" != "$2" ] && echo $1" != "$2

[will@localhost ShellScript]$

shell script : do math

[will@localhost ShellScript]$ cat number.sh
#!/bin/sh

a=3

b=5

ab=$a*$b

echo $ab

ab=$(($a*$b))

echo $ab

[will@localhost ShellScript]$

shell script : function

[will@localhost ShellScript]$ cat function.sh

#!/bin/sh
function printit(){
        echo "Your choice is $1"

}
case $1 in

  "one")

        printit 1
        ;;
  "two")
        printit 2
        ;;
  "three")
        printit 3
        ;;
  *)
        echo "Usage {one|two|three}"
        ;;

esac

[will@localhost ShellScript]$

shell script : string for loop

[will@localhost ShellScript]$ cat for.string.sh
#!/bin/sh

for animal in elephant dinosaur kangaroo
do

echo "There are ""$animal"" in the zoo."
done

[will@localhost ShellScript]$

shell script : for loop

[will@localhost ShellScript]$ cat for.sh
#!/bin/sh

s=0

for (( i=1; i<=10; i=i+1 ))

do

s=$(($s+$i))

done

echo "The result of '1+2+3+...+10' is ==> $s"

[will@localhost ShellScript]$

shell script : variable save command result

[will@localhost ShellScript]$ cat date.sh
#!/bin/bash

ddd=`/bin/date`

echo -e "It is \""$ddd"\" now."

[will@localhost ShellScript]$

shell script : condition without if

[will@localhost ShellScript]$ cat cond.sh
#!/bin/sh

read -p "Please input (Y/N): " yn

[ "$yn" == "Y" -o "$yn" == "y" ] && echo "Oh, Yes!" && exit 0
[ "$yn" == "N" -o "$yn" == "n" ] && echo "Oh, No!" && exit 0
echo "I don't know what your choice is." && exit 0
[will@localhost ShellScript]$

shell script : if condition

[will@localhost ShellScript]$ cat cond.if.sh

#!/bin/sh

read -p "Please input (Y/N): " yn

if [ "$yn" == "Y" ] || [ "$yn" == "y" ]; then

echo "Oh, Yes!"

elif [ "$yn" == "N" ] || [ "$yn" == "n" ]; then

echo "Oh, No!"

else

echo "I don't know what your choice is."
fi

shell script case

[will@localhost ShellScript]$ cat case.sh
#!/bin/sh

case $1 in

"hello")

        echo "Hello, how are you ?"
        ;;
  "")
        echo "You MUST input parameters, ex> $0 someword"
        ;;
  *)
        echo "Usage $0 {hello}"
        ;;

esac

[will@localhost ShellScript]$

txt2html

http://txt2html.sourceforge.net/

select stdin example

       #include <stdio.h>
       #include <sys/time.h>
       #include <sys/types.h>
       #include <unistd.h>
       int
       main(void) {
           fd_set rfds;
           struct timeval tv;
           int retval;
           /* Watch stdin (fd 0) to see when it has input. */
           FD_ZERO(&rfds);
           FD_SET(0, &rfds);
           /* Wait up to five seconds. */
           tv.tv_sec = 5;
           tv.tv_usec = 0;
           retval = select(1, &rfds, NULL, NULL, &tv);
           /* Don¡¦t rely on the value of tv now! */
           if (retval == -1)
               perror("select()");
           else if (retval)
               printf("Data is available now.\n");
               /* FD_ISSET(0, &rfds) will be true. */
           else
               printf("No data within five seconds.\n");
           return 0;
       }