*    $0 ：即命令本身，相當于c/c++中的argv[0]
    *    $1 ：第一個參數(shù).
    *    $2, $3, $4 ... ：第2、3、4個參數(shù)，依次類推。
    *    $#  參數(shù)的個數(shù)，不包括命令本身
    *    $@ ：參數(shù)本身的列表，也不包括命令本身
    *    $* ：和$@相同，但"$*" 和 "$@"(加引號)并不同，"$*"將所有的參數(shù)解釋成一個字符串，而"$@"是一個參數(shù)數(shù)組。

#!/bin/bash
if [ $# -lt 1 ]; then
    echo "error.. need args"
    exit 1
fi
echo "commond is $0"
echo "args are:"
for arg in "$@"
do
    echo $arg
done

./getargs.sh 11 22 cc
commond is ./getargs.sh
args are:
11
22
cc

[root@jbxue ~]$ type getopt
getopt is /usr/bin/getopt
[root@jbxue ~]$ type getopts
getopts is a shell builtin

echo $*
while getopts ":a:bc" opt
do
        case $opt in
                a ) echo $optarg
                    echo $optind;;
                b ) echo "b $optind";;
                c ) echo "c $optind";;
                ? ) echo "error"
                    exit 1;;
        esac
done
echo $optind
shift $(($optind - 1))
#通過shift $(($optind - 1))的處理，$*中就只保留了除去選項內(nèi)容的參數(shù)，可以在其后進行正常的shell編程處理了。
echo $0
echo $*

./getopts.sh -a 11 -b -c
-a 11 -b -c
11
3
b 4
c 5
5
./getopts.sh

#!/bin/bash
# a small example program for using the new getopt(1) program.
# this program will only work with bash(1)
# an similar program using the tcsh(1) script. language can be found
# as parse.tcsh
# example input and output (from the bash prompt):
# ./parse.bash -a par1 'another arg' --c-long 'wow!*\?' -cmore -b " very long "
# option a
# option c, no argument
# option c, argument `more'
# option b, argument ` very long '
# remaining arguments:
# --> `par1'
# --> `another arg'
# --> `wow!*\?'
# note that we use `"$@"' to let each command-line parameter expand to a
# separate word. the quotes around `$@' are essential!
# we need temp as the `eval set --' would nuke the return value of getopt.
#-o表示短選項，兩個冒號表示該選項有一個可選參數(shù)，可選參數(shù)必須緊貼選項
#如-carg 而不能是-c arg
#--long表示長選項
#"$@"在上面解釋過
# -n:出錯時的信息
# -- ：舉一個例子比較好理解：
#我們要創(chuàng)建一個名字為 "-f"的目錄你會怎么辦？
# mkdir -f #不成功，因為-f會被mkdir當作選項來解析，這時就可以使用
# mkdir -- -f 這樣-f就不會被作為選項。
temp=`getopt -o ab:c:: --long a-long,b-long:,c-long:: \
     -n 'example.bash' -- "$@"`
if [ $? != 0 ] ; then echo "terminating..." >&2 ; exit 1 ; fi
# note the quotes around `$temp': they are essential!
#set 會重新排列參數(shù)的順序，也就是改變$1,$2...$n的值，這些值在getopt中重新排列過了
eval set -- "$temp"
#經(jīng)過getopt的處理，下面處理具體選項。
while true ; do
        case "$1" in
                -a|--a-long) echo "option a" ; shift ;;
                -b|--b-long) echo "option b, argument \`$2'" ; shift 2 ;;
                -c|--c-long)
                        # c has an optional argument. as we are in quoted mode,
                        # an empty parameter will be generated if its optional
                        # argument is not found.
                        case "$2" in
                                "") echo "option c, no argument"; shift 2 ;;
                                *)  echo "option c, argument \`$2'" ; shift 2 ;;
                        esac ;;
                --) shift ; break ;;
                *) echo "internal error!" ; exit 1 ;;
        esac
done
echo "remaining arguments:"
for arg do
   echo '--> '"\`$arg'" ;
done

./getopt.sh --b-long abc -a -c33 remain
option b, argument `abc'
option a
option c, argument `33'
remaining arguments:
--> `remain'