bash使用getopt解析长短参数

bash使用getopt解析长短参数

#!/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):

# ./option_test.sh -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表示短选项，两个冒号表示该选项有一个可选参数，可选参数必须紧贴选项

#如-carg 而不能是-c arg

#--long表示长选项

#"$@"在上面解释过

# -n:出错时的信息

# -- ：举一个例子比较好理解：

#我们要创建一个名字为 "-f"的目录你会怎么办？

# mkdir -f #不成功，因为-f会被mkdir当作选项来解析，这时就可以使用

# mkdir -- -f 这样-f就不会被作为选项。

TEMP=`getopt -o ab:c:: -l a-long,b-long:,c-long:: -n 'option_test.sh' -- "$@"`

echo "TEMP:{$TEMP}"

if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi

# Note the quotes around `$TEMP': they are essential!

#set 会重新排列参数的顺序，也就是改变$1,$2...$n的值，这些值在getopt中重新排列过了

eval set -- "$TEMP" #必须用eval

echo "\$#: $#"

for i in "$@"; do

    echo "{$i}"

done

#经过getopt的处理，下面处理具体选项。

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

==================================================================================

$ set -- a ' b '

$ echo $#

2

$ a="a ' b '"

$ set -- $a

$ echo $#

4

$ set -- "$a"

$ echo $#

1