Linux shell中getopts命令學習--實現一個添加yum源的指令碼

標籤：linux   shell   getopts   

    getopts是bash shell的內建命令，作用是在shell指令碼中解析命令列傳遞、傳遞給函數或傳遞給另一個調用的shell指令碼的位置參數（選項或參數，後面會講解，getopts只支援短選項，若要解析長選項請參考getopt）。

getopts命令文法:

    getopts optstring name [arg]    

相關的術語：

  選項（option）：GNU風格的命令選項，如：-x,-y等減號加上單個字母的為短選項；--help為長選項；

       選項的參數：某些選項之後必須尾隨參數，如：-f xxx.conf，xxx.conf稱為選項的參數;

  參數：位於最後一個選項，空格之後的字串;

      optionstring：用於匹配option的字串，optionstring中每個字母對應的是去除減號後的option（這裡指短選項）;

      [arg]：用來替代位置參數被getopts解析的，類似於將[email protected]賦值給arg;

      OPTIND: getopts的一個內建變數，表示下一個要處理的參數索引，每次shell或shell指令碼執行的時候初始化為1;

   name: getopts每解析到一個選項，都會將該選項對應的字元複製給name變數

getopts命令的簡單解釋：

    1.optstring中如果字母后面跟隨著冒號，表示該字母所表示的option後面是帶參數的，參數值將被賦到OPTARG變數中。如test.sh中包含：getopts "i:" name; 那麼在命令列執行test.sh -i 1.1.1.1時，$name=‘i‘,$OPTARG=1.1.1.1

    getopts包含兩種錯誤處理的模式

    安靜模式下：

    2.optstring的第一個字元為冒號時，getopts將使用安靜模式來報告錯誤（但不會有錯誤提示輸出），生產環境中一般使用該模式；

    3.如果輸入一個無效的字元作為選項時（optstring中沒包含的字元），將‘？’賦值給name變數，該無效選項的字元賦值給OPTARG變數；

    4.如果選項要求跟隨的參數沒找到，getopts會將冒號":"賦值給name變數,設定OPTARG為發現的選項字元；

    非安靜模式下：

    5.如果getopts不處於安靜模式，一個無效的選項被發現，‘?‘將被設定到name變數中且unset OPTARG

    6.如果選項要求的參數沒找到，‘?‘將被設定到name，OPTARG將被unset，錯誤提示資訊將被列印

   退出狀態：

    7.如果shell中$OPTERR環境變數值為0，getopts將關閉錯誤資訊的列印，即使optstring中第一個字元不是冒號。預設的$OPTERR值為1

    8.getopts一般情況下解析位置參數（$0-$9），但位置參數超過這個範圍時仍然能被正確解析

    9.如果選項被發現（匹配optionstring）返回true，如果遇到了選項的結尾或者有錯誤則返回false

指令碼執行個體：

1. 不帶選擇性參數[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

執行：

[[email protected] ~]# 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. 帶選擇性參數[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

執行：

[[email protected] ~]# 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. 實現一個添加yum源的指令碼

#!/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

指令碼的執行：

1）列印命令協助

[[email protected] ~]# ./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）不帶任何選項參數時，自動下載163和epel的yum源repofile

[[email protected] ~]# ./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）從指定的url中下載repofile

[[email protected] ~]# ./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）建立自訂的repofile

[[email protected] ~]# ./load_yum_repo.sh -f test -n test -u file:///mnt

[[email protected] ~]# cat /etc/yum.repos.d/test.repo 

[test]

name=test

baseurl=file:///mnt

enabled=1

gpgcheck=0

Linux shell中getopts命令學習--實現一個添加yum源的指令碼