Linux shell中getopts命令学习--实现一个添加yum源的脚本

    getopts是bash shell的内建命令，作用是在shell脚本中解析命令行传递、传递给函数或传递给另一个调用的shell脚本的位置参数（选项或参数，后面会讲解，getopts只支持短选项，若要解析长选项请参考getopt）。

getopts命令语法:

    getopts optstring name [arg]    

相关的术语：

  选项（option）：GNU风格的命令选项，如：-x,-y等减号加上单个字母的为短选项；--help为长选项；

       选项的参数：某些选项之后必须尾随参数，如：-f xxx.conf，xxx.conf称为选项的参数;

  参数：位于最后一个选项，空格之后的字符串;

      optionstring：用于匹配option的字符串，optionstring中每个字母对应的是去除减号后的option（这里指短选项）;

      [arg]：用来替代位置参数被getopts解析的，类似于将$@赋值给arg;

      OPTIND: getopts的一个内置变量，表示下一个要处理的参数索引，每次shell或shell脚本执行的时候初始化为1;

   name: getopts每解析到一个选项，都会将该选项对应的字符复制给name变量

getopts命令的简单解释：

    1.optstring中如果字母后面跟随着冒号，表示该字母所表示的option后面是带参数的，参数值将被赋到OPTARG变量中。如test.sh中包含：getopts "i:" name; 那么在命令行执行test.sh -i 1.1.1.1时，$name=‘i‘,$OPTARG=1.1.1.1

    getopts包含两种错误处理的模式

    安静模式下：

    2.optstring的第一个字符为冒号时，getopts将使用安静模式来报告错误（但不会有错误提示输出），生产环境中一般使用该模式；

    3.如果输入一个无效的字符作为选项时（optstring中没包含的字符），将‘？’赋值给name变量，该无效选项的字符赋值给OPTARG变量；

    4.如果选项要求跟随的参数没找到，getopts会将冒号":"赋值给name变量,设置OPTARG为发现的选项字符；

    非安静模式下：

    5.如果getopts不处于安静模式，一个无效的选项被发现，‘?‘将被设置到name变量中且unset OPTARG

    6.如果选项要求的参数没找到，‘?‘将被设置到name，OPTARG将被unset，错误提示信息将被打印

   退出状态：

    7.如果shell中$OPTERR环境变量值为0，getopts将关闭错误信息的打印，即使optstring中第一个字符不是冒号。默认的$OPTERR值为1

    8.getopts一般情况下解析位置参数（$0-$9），但位置参数超过这个范围时仍然能被正确解析

    9.如果选项被发现（匹配optionstring）返回true，如果遇到了选项的结尾或者有错误则返回false

脚本实例：

1. 不带可选参数[arg]

#!/bin/bash

echo "OPTIND starts at $OPTIND"

while getopts ":q:p" optname

do

    case "$optname" in

    "p")

        echo "Option $optname is specified"

        ;;

    "q")

        echo "Option $optname has value $OPTARG"

        #shift 1

        shift $((OPTIND-2))

        ;;

    "?")

        echo "Unknown option $OPTARG"

        ;;

    ":")

        echo "No argument value for option $OPTARG"

        ;;

    *)

        # Should not occur

        echo "Unknown error while processing options"

        ;;

    esac

echo "OPTIND is now $OPTIND"

done

执行：

[root@dns1 ~]# bash test_getopts.sh -q aa -p -h

OPTIND starts at 1

Option q has value aa

OPTIND is now 3

Unknown option h

OPTIND is now 4

2. 带可选参数[arg]

#!/bin/bash

echo "OPTIND starts at $OPTIND"

while getopts ":q:p" optname "-q qarg" "-p" "-h" 

do

    case "$optname" in

    "p")

        echo "Option $optname is specified"

        ;;

    "q")

        echo "Option $optname has value $OPTARG"

        ;;

    "?")

        echo "Unknown option $OPTARG"

        ;;

    ":")

        echo "No argument value for option $OPTARG"

        ;;

    *)

        # Should not occur

        echo "Unknown error while processing options"

        ;;

    esac

echo "OPTIND is now $OPTIND"

done

执行：

[root@dns1 ~]# bash test_getopts.sh 

OPTIND starts at 1

Option q has value  qarg

OPTIND is now 2

Option p is specified

OPTIND is now 3

Unknown option h

OPTIND is now 4

3. 实现一个添加yum源的脚本

#!/bin/bash

#

# Descrition: this script will download the yum repo file from mirrors.163.com and epel for CENTOS/REDHAT DISTIBUTE

# Author: Gateray Jo 

# mail: [email protected]

set -e 

prog=`basename $0`

arch=`uname -m`

release=`lsb_release -r | sed ‘s/.*:[[:space:]]*//‘`

function usage() {

cat<<eof

Usage: ./${prog} [options] [arg]

       -h: print the command help.

       -u: specified the baseurl for yum repository, must use with -ufn combination.

       -f: specified the name of local repofile(no ".repo" ext name) which place in /etc/yum.repos.d/, must use with -ufn 

           combination.

       -n: specified the repo‘s name in xxx.repo file, must use with -ufn combination.

       -d: specified the url of repofile which will be download to /etc/yum.repos.d/.

       By default, nothing options are specified which will download epel and 163 yum repofile.        

eof

}

function default() {

    major_rel=${release%%.*}

    # download 163 repofile

    printf "Download 163 repofile from mirrors.163.com:\n"

    wget -P /etc/yum.repos.d http://mirrors.163.com/.help/CentOS${major_rel}-Base-163.repo 

    printf "Download epel repofile from http://dl.fedoraproject.org.:\n"

    if [[ $arch = "x86_64" ]]; then

        [ ${major_rel} -eq 5 ] && rpm -ivh http://dl.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm

        [ ${major_rel} -eq 6 ] && rpm -ivh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm    

    else 

        [ ${major_rel} -eq 5 ] && rpm -ivh http://dl.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm

        [ ${major_rel} -eq 6 ] && rpm -ivh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

    fi

    return $?

}

[ $# -eq 0 ] && default && exit $?

while getopts ":hu:f:n:d:" optname; do

    case $optname in

    "h")

        usage && exit 0

        ;;

    "u")

        u_opt=1

        u_arg=$OPTARG

        ;;

    "f")

        f_opt=1

        u_arg=$OPTARG

        ;;

    "n")

        n_opt=1

        n_arg=$OPTARG

        ;;

    "d")

        wget -P /etc/yum.repos.d $OPTARG

        exit $?

        ;;

    "?")

        echo "Unknown option $OPTARG"

        usage && exit 1

        ;;

    ":")

        echo "It is need a option value for $OPTARG"

        usage && exit 1

        ;;

    *)

        echo ‘Unknown error!‘ && exit 1

        ;;

    esac

done

if [ $u_opt -eq 1 -a $f_opt -eq 1 -a $n_opt -eq 1 ]; then

    if [[ ${n_arg} =~ ‘-‘ ]]; then

        echo "Invalid value for -n option, \"${n_arg}\" is include ‘-‘ character."

        exit 1

    fi

cat >> /etc/yum.repos.d/${f_arg}.repo <<eof

[${n_arg}]

name=${n_arg}

baseurl=${u_arg}

enabled=1

gpgcheck=0

eof

else

    usage && exit 1

fi

脚本的执行：

1）打印命令帮助

[root@dns1 ~]# ./load_yum_repo.sh -h

Usage: ./load_yum_repo.sh [options] [arg]

       -h: print the command help.

       -u: specified the baseurl for yum repository, must use with -ufn combination.

       -f: specified the name of local repofile(no ".repo" ext name) which place in /etc/yum.repos.d/, must use with -ufn 

           combination.

       -n: specified the repo‘s name in xxx.repo file, must use with -ufn combination.

       -d: specified the url of repofile which will be download to /etc/yum.repos.d/.

       By default, nothing options are specified which will download epel and 163 yum repofile.  

2）不带任何选项参数时，自动下载163和epel的yum源repofile

[root@dns1 ~]# ./load_yum_repo.sh 

Download 163 repofile from mirrors.163.com:

--2015-04-04 22:23:05--  http://mirrors.163.com/.help/CentOS6-Base-163.repo

Resolving mirrors.163.com... 123.58.173.106

Connecting to mirrors.163.com|123.58.173.106|:80... connected.

HTTP request sent, awaiting response... 200 OK

Length: 2006 (2.0K) [application/octet-stream]

Saving to: “/etc/yum.repos.d/CentOS6-Base-163.repo”

100%[==========================================================================================>] 2,006       --.-K/s   in 0.05s   

2015-04-04 22:23:05 (39.2 KB/s) - “/etc/yum.repos.d/CentOS6-Base-163.repo” saved [2006/2006]

Download epel repofile from http://dl.fedoraproject.org.:

Retrieving http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

warning: /var/tmp/rpm-tmp.wVrCDS: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY

Preparing...                ########################################### [100%]

   1:epel-release           ########################################### [100%]

3）从指定的url中下载repofile

[root@dns1 ~]# ./load_yum_repo.sh -d http://mirrors.163.com/.help/CentOS6-Base-163.repo

--2015-04-04 22:13:47--  http://mirrors.163.com/.help/CentOS6-Base-163.repo

Resolving mirrors.163.com... 123.58.173.106

Connecting to mirrors.163.com|123.58.173.106|:80... connected.

HTTP request sent, awaiting response... 200 OK

Length: 2006 (2.0K) [application/octet-stream]

Saving to: “/etc/yum.repos.d/CentOS6-Base-163.repo”

100%[==========================================================================================>] 2,006       --.-K/s   in 0.05s   

2015-04-04 22:13:47 (40.9 KB/s) - “/etc/yum.repos.d/CentOS6-Base-163.repo” saved [2006/2006]

4）创建自定义的repofile

[root@dns1 ~]# ./load_yum_repo.sh -f test -n test -u file:///mnt

[root@dns1 ~]# cat /etc/yum.repos.d/test.repo 

[test]

name=test

baseurl=file:///mnt

enabled=1

gpgcheck=0