{"id":1278,"date":"2023-12-05T11:41:21","date_gmt":"2023-12-05T03:41:21","guid":{"rendered":"https:\/\/www.qiangzhenshuai.com\/?p=1278"},"modified":"2024-08-02T14:43:04","modified_gmt":"2024-08-02T06:43:04","slug":"shell-if","status":"publish","type":"post","link":"https:\/\/www.qiangzhenshuai.com\/?p=1278","title":{"rendered":"SHELL-IF"},"content":{"rendered":"<h1>1.if\u7684\u57fa\u672c\u8bed\u6cd5<\/h1>\n<p>if\u4e0e[\u4e4b\u95f4\u8981\u6709\u7a7a\u683c<br \/>\n[]\u4e0e\u5224\u65ad\u6761\u4ef6\u4e4b\u95f4\u4e5f\u5fc5\u987b\u6709\u7a7a\u683c<br \/>\n]\u4e0e;\u4e4b\u95f4\u4e0d\u80fd\u6709\u7a7a\u683c<\/p>\n<h1>2.\u5bf9\u5b57\u7b26\u4e32\u7684\u5224\u65ad<\/h1>\n<p>if [ str1=str2 ];then fi #\u5f53\u4e24\u4e2a\u5b57\u7b26\u4e32\u76f8\u540c\u65f6\u8fd4\u56de\u771f<br \/>\nif [ str1!=str2 ];then fi #\u5f53\u4e24\u4e2a\u5b57\u7b26\u4e32\u4e0d\u76f8\u7b49\u65f6\u8fd4\u56de\u771f<br \/>\nif [ -n str1 ];then fi #\u5f53\u5b57\u7b26\u4e32\u7684\u957f\u5ea6\u5927\u4e8e0\u65f6\u8fd4\u56de\u771f (\u5224\u65ad\u53d8\u91cf\u662f\u5426\u6709\u503c)<br \/>\nif [ -z str1 ];then fi #\u5f53\u5b57\u7b26\u4e32\u7684\u957f\u5ea6\u4e3a0\u65f6\u8fd4\u56de\u771f<\/p>\n<h1 id=\"1-\u683c\u5f0f\">3.\u683c\u5f0f<\/h1>\n<h4 id=\"11-\u5355\u5206\u652f\u8bed\u53e5\u7ed3\u6784\">\u5355\u5206\u652f\u8bed\u53e5\u7ed3\u6784<\/h4>\n<pre class=\"prettyprint set-code-show\" data-index=\"0\">if [ \u6761\u4ef6\u8868\u8fbe\u5f0f ]; then\r\n    \u6307\u4ee4 \r\nfi<\/pre>\n<h4 id=\"12-\u53cc\u5206\u652f\u8bed\u53e5\u7ed3\u6784\">\u53cc\u5206\u652f\u8bed\u53e5\u7ed3\u6784<\/h4>\n<pre data-index=\"1\">if [ \u6761\u4ef6\u8868\u8fbe\u5f0f ]; then \r\n    \u6307\u4ee4\u4e00 \r\nelse \r\n    \u6307\u4ee4\u4e8c \r\nfi<\/pre>\n<h4 id=\"13-\u591a\u5206\u652f\u8bed\u53e5\u7ed3\u6784\">\u591a\u5206\u652f\u8bed\u53e5\u7ed3\u6784<\/h4>\n<pre data-index=\"2\">if [ -f file ]; then\r\n   echo \"yes yes yes\"\r\nelif [ -z file ]; then\r\n   echo \"yes yes\"\r\nelse\r\n   echo \"nonono\"\r\nfi<\/pre>\n<h1>4.if else<\/h1>\n<p data-pid=\"XWYdrDR7\">\u5355\u72ec\u7684\u4e00\u4e2a if else \u8bed\u53e5\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<div>\n<pre>if condition\r\nthen\r\n    \u7b26\u5408 condition \u7684\u6267\u884c\u8bed\u53e5\r\nelse\r\n    \u4e0d\u7b26\u5408 condition \u7684\u6267\u884c\u8bed\u53e5\r\nfi<\/pre>\n<\/div>\n<p data-pid=\"tsZafdqa\">\u8fd9\u91cc then \u4e5f\u53ef\u4ee5\u5199\u5230\u4e0e if \u5728\u4e00\u884c\u4e2d\u3002<\/p>\n<h2 data-pid=\"36w1FSCc\">if else \u8bed\u53e5<\/h2>\n<div>\n<pre>#!\/bin\/bash\r\n \r\nfile=\"\/root\"\r\nif [ -d $file ]\r\nthen\r\n    echo \"$file is directory!\"\r\nelse\r\n    echo \"$file is not directory!\"\r\nfi<\/pre>\n<\/div>\n<h1>5.if elif<\/h1>\n<p data-pid=\"YzBBob74\"><b>\u6ce8\u610f\uff1a<\/b>Shell \u91cc\u5c06 else if \u7b80\u5199\u4e3a elif\uff0celif \u4e5f\u8981\u6709 then\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<div>\n<pre>if condition_1\r\nthen\r\n    \u7b26\u5408 condition_1 \u7684\u6267\u884c\u8bed\u53e5\r\nelif condition_2\r\nthen\r\n    \u7b26\u5408 condition_2 \u7684\u6267\u884c\u8bed\u53e5\r\nelse \r\n    \u4e0d\u7b26\u5408 condition_1 \u548c condition_2 \u7684\u6267\u884c\u8bed\u53e5\r\nfi<\/pre>\n<\/div>\n<h2 data-pid=\"NkNrbamk\">if elif \u8bed\u53e5<\/h2>\n<div class=\"highlight\">\n<pre>#!\/bin\/bash\r\n \r\nfile=\"\/root\"\r\nif [ -f $file ]\r\nthen\r\n    echo \"$file is regular file!\"\r\nelif [ -d $file ]\r\nthen\r\n    echo \"$file is directory!\"\r\nelse\r\n    echo \"$file is not regular file and directory\"\r\nfi<\/pre>\n<h1>6.else\u548celif\u533a\u522b<\/h1>\n<\/div>\n<p>\u5728Shell\u811a\u672c\u4e2d\uff0celse\u548celif\u90fd\u662f\u7528\u4e8e\u5728if\u8bed\u53e5\u4e2d\u5904\u7406\u591a\u4e2a\u6761\u4ef6\u7684\u5173\u952e\u5b57\u3002<\/p>\n<p>else\uff1aelse\u5173\u952e\u5b57\u7528\u4e8e\u5728if\u8bed\u53e5\u4e2d\u5904\u7406\u5f53\u6761\u4ef6\u4e3a\u5047\u65f6\u6267\u884c\u7684\u4ee3\u7801\u5757\u3002\u5f53if\u8bed\u53e5\u4e2d\u7684\u6761\u4ef6\u4e3a\u5047\u65f6\uff0celse\u540e\u9762\u7684\u4ee3\u7801\u5757\u5c06\u88ab\u6267\u884c\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>if [ condition ]; then\r\n    # \u5982\u679c\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u6267\u884c\u8fd9\u91cc\u7684\u4ee3\u7801\r\nelse\r\n    # \u5982\u679c\u6761\u4ef6\u4e3a\u5047\uff0c\u5219\u6267\u884c\u8fd9\u91cc\u7684\u4ee3\u7801\r\nfi\r\n<\/pre>\n<p>elif\uff1aelif\u5173\u952e\u5b57\u7528\u4e8e\u5728if\u8bed\u53e5\u4e2d\u5904\u7406\u591a\u4e2a\u6761\u4ef6\u7684\u60c5\u51b5\u3002\u5f53if\u8bed\u53e5\u4e2d\u7684\u7b2c\u4e00\u4e2a\u6761\u4ef6\u4e3a\u5047\u65f6\uff0c\u4f1a\u68c0\u67e5elif\u540e\u9762\u7684\u6761\u4ef6\uff0c\u5982\u679c\u6709\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u6267\u884c\u5bf9\u5e94\u7684\u4ee3\u7801\u5757\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre>if [ condition1 ]; then\r\n    # \u5982\u679c\u6761\u4ef61\u4e3a\u771f\uff0c\u5219\u6267\u884c\u8fd9\u91cc\u7684\u4ee3\u7801\r\nelif [ condition2 ]; then\r\n    # \u5982\u679c\u6761\u4ef61\u4e3a\u5047\uff0c\u4f46\u6761\u4ef62\u4e3a\u771f\uff0c\u5219\u6267\u884c\u8fd9\u91cc\u7684\u4ee3\u7801\r\nelse\r\n    # \u5982\u679c\u6761\u4ef61\u548c\u6761\u4ef62\u90fd\u4e3a\u5047\uff0c\u5219\u6267\u884c\u8fd9\u91cc\u7684\u4ee3\u7801\r\nfi\r\n<\/pre>\n<p>\u56e0\u6b64\uff0celse\u7528\u4e8e\u5904\u7406if\u8bed\u53e5\u4e2d\u7684\u9ed8\u8ba4\u60c5\u51b5\uff08\u5373\u5f53\u6240\u6709\u6761\u4ef6\u90fd\u4e3a\u5047\u65f6\u6267\u884c\u7684\u4ee3\u7801\uff09\uff0c\u800celif\u7528\u4e8e\u5904\u7406\u591a\u4e2a\u6761\u4ef6\u7684\u60c5\u51b5\uff0c\u5f53\u7b2c\u4e00\u4e2a\u6761\u4ef6\u4e3a\u5047\u65f6\uff0c\u68c0\u67e5\u4e0b\u4e00\u4e2a\u6761\u4ef6\u3002\u8fd9\u4e24\u4e2a\u5173\u952e\u5b57\u5728if\u8bed\u53e5\u4e2d\u4e00\u8d77\u4f7f\u7528\uff0c\u53ef\u4ee5\u5b9e\u73b0\u66f4\u590d\u6742\u7684\u6761\u4ef6\u903b\u8f91\u3002<\/p>\n<h1>7.\u6761\u4ef6\u8868\u8fbe\u5f0f\u7684\u5185\u5bb9<\/h1>\n<h4>\u5b57\u7b26\u4e32\u7684\u5224\u65ad<\/h4>\n<p>str1 = str2\u3000\u3000\u3000\u3000\u3000\u3000\u5f53\u4e24\u4e2a\u4e32\u6709\u76f8\u540c\u5185\u5bb9\u3001\u957f\u5ea6\u65f6\u4e3a\u771f<br \/>\nstr1 != str2\u3000\u3000\u3000\u3000\u3000 \u5f53\u4e32str1\u548cstr2\u4e0d\u7b49\u65f6\u4e3a\u771f<br \/>\n-n str1\u3000\u3000\u3000\u3000\u3000\u3000\u3000 \u5f53\u4e32\u7684\u957f\u5ea6\u5927\u4e8e0\u65f6\u4e3a\u771f(\u4e32\u975e\u7a7a)<br \/>\n-z str1\u3000\u3000\u3000\u3000\u3000\u3000\u3000 \u5f53\u4e32\u7684\u957f\u5ea6\u4e3a0\u65f6\u4e3a\u771f(\u7a7a\u4e32)<br \/>\nstr1\u3000\u3000\u3000\u3000\u3000\u3000\u3000\u3000 \u5f53\u4e32str1\u4e3a\u975e\u7a7a\u65f6\u4e3a\u771f<\/p>\n<h4>\u6570\u5b57\u7684\u5224\u65ad<\/h4>\n<p>int1 -eq int2\u3000\u3000\u3000\u3000\u4e24\u6570\u76f8\u7b49\u4e3a\u771f<br \/>\nint1 -ne int2\u3000\u3000\u3000\u3000\u4e24\u6570\u4e0d\u7b49\u4e3a\u771f<br \/>\nint1 -gt int2\u3000\u3000\u3000\u3000int1\u5927\u4e8eint2\u4e3a\u771f<br \/>\nint1 -ge int2\u3000\u3000\u3000\u3000int1\u5927\u4e8e\u7b49\u4e8eint2\u4e3a\u771f<br \/>\nint1 -lt int2\u3000\u3000\u3000\u3000int1\u5c0f\u4e8eint2\u4e3a\u771f<br \/>\nint1 -le int2\u3000\u3000\u3000\u3000int1\u5c0f\u4e8e\u7b49\u4e8eint2\u4e3a\u771f<\/p>\n<h4>\u6587\u4ef6\u7684\u5224\u65ad<\/h4>\n<p>-r file\u3000\u3000\u3000\u3000\u3000\u7528\u6237\u53ef\u8bfb\u4e3a\u771f<br \/>\n-w file\u3000\u3000\u3000\u3000\u3000\u7528\u6237\u53ef\u5199\u4e3a\u771f<br \/>\n-x file\u3000\u3000\u3000\u3000\u3000\u7528\u6237\u53ef\u6267\u884c\u4e3a\u771f<br \/>\n-f file\u3000\u3000\u3000\u3000\u3000\u6587\u4ef6\u4e3a\u6b63\u89c4\u6587\u4ef6\u4e3a\u771f<br \/>\n-d file\u3000\u3000\u3000\u3000\u3000\u6587\u4ef6\u4e3a\u76ee\u5f55\u4e3a\u771f<br \/>\n-c file\u3000\u3000\u3000\u3000\u3000\u6587\u4ef6\u4e3a\u5b57\u7b26\u7279\u6b8a\u6587\u4ef6\u4e3a\u771f<br \/>\n-b file\u3000\u3000\u3000\u3000\u3000\u6587\u4ef6\u4e3a\u5757\u7279\u6b8a\u6587\u4ef6\u4e3a\u771f<br \/>\n-s file\u3000\u3000\u3000\u3000\u3000\u6587\u4ef6\u5927\u5c0f\u975e0\u65f6\u4e3a\u771f<br \/>\n-t file\u3000\u3000\u3000\u3000\u3000\u5f53\u6587\u4ef6\u63cf\u8ff0\u7b26(\u9ed8\u8ba4\u4e3a1)\u6307\u5b9a\u7684\u8bbe\u5907\u4e3a\u7ec8\u7aef\u65f6\u4e3a\u771f<\/p>\n<h4 id=\"24-\u590d\u6742\u903b\u8f91\u5224\u65ad\">\u590d\u6742\u903b\u8f91\u5224\u65ad<\/h4>\n<p>\u6761\u4ef6\u8868\u8fbe\u5f0f\u4e2d\u53ef\u80fd\u6709\u591a\u4e2a\u6761\u4ef6\uff0c\u9700\u8981\u4f7f\u7528\u4e0e\u6216\u975e\u7b49\u903b\u8f91\u64cd\u4f5c\u3002<\/p>\n<pre data-index=\"6\">-a\uff1a\u4e0e \r\n-o\uff1a\u6216 \r\n!\uff1a\u975e<\/pre>\n<h2>\u6848\u4f8b<\/h2>\n<p><span class=\"hljs-meta prompt_\">#<\/span><span class=\"language-bash\">!\/bin\/bash<\/span><br \/>\nread -p &#8220;\u8bf7\u8f93\u5165\u4f60\u7684\u5206\u6570:&#8221; score<br \/>\nif [ $score -ge 0 ]&amp;&amp;[ $score -lt 60 ];then<br \/>\necho &#8220;sorry,you are lost!&#8221;<br \/>\nelif [ $score -ge 60 ]&amp;&amp;[ $score -lt 85 ];then<br \/>\necho &#8220;just soso!&#8221;<br \/>\nelif [ $score -le 100 ]&amp;&amp;[ $score -ge 85 ];then<br \/>\necho &#8220;good job!&#8221;<br \/>\nelse<br \/>\necho &#8220;input score is wrong , the range is [0-100]!&#8221;<br \/>\nfi<\/p>\n<h4>\u5f53\u7136\uff0c\u4e0a\u9762\u7684\u5b9e\u4f8b\u4e5f\u53ef\u4ee5\u7528 -a \u6765\u6539\u5199\uff1a<\/h4>\n<p><span class=\"hljs-meta prompt_\">#<\/span><span class=\"language-bash\">!\/bin\/bash<\/span><br \/>\nread -p &#8220;\u8bf7\u8f93\u5165\u4f60\u7684\u5206\u6570:&#8221; score<br \/>\nif [ $score -ge 0 -a $score -lt 60 ];then<br \/>\necho &#8220;sorry,you are lost!&#8221;<br \/>\nelif [ $score -ge 60 -a $score -lt 85 ];then<br \/>\necho &#8220;just soso!&#8221;<br \/>\nelif [ $score -le 100 -a $score -ge 85 ];then<br \/>\necho &#8220;good job!&#8221;<br \/>\nelse<br \/>\necho &#8220;input score is wrong , the range is [0-100]!&#8221;<br \/>\nfi<\/p>\n<h4>\u8f93\u5165\u4e24\u4e2a\u6574\u6570 \u4f7f\u7528if\u5224\u65ad\u4e24\u4e2a\u6574\u6570\u8c01\u5927\u8c01\u5c0f\u6216\u7b49\u4e8e<\/h4>\n<div>[root@shell \/server\/scripts]$ cat count3.sh<\/div>\n<div>#!\/bin\/sh<\/div>\n<div>read -p &#8220;\u8bf7\u8f93\u5165\u4e24\u4e2a\u6574\u6570: &#8221; num1 num2<\/div>\n<div>expr $num1 + $num2 &amp;&gt;\/dev\/null<\/div>\n<div>if [ $? -ne 0 ];then<\/div>\n<div>echo \u8bf7\u8f93\u5165\u6b63\u786e\u7684\u6570\u5b57<\/div>\n<div>exit<\/div>\n<div>fi<\/div>\n<div>if [ $num1 -gt $num2 ]<\/div>\n<div>then<\/div>\n<div>echo &#8220;$num1&gt;$num2&#8221;<\/div>\n<div>elif [ $num1 -lt $num2 ]<\/div>\n<div>then<\/div>\n<div>\u00a0 echo &#8220;$num1&lt;$num2&#8221;<\/div>\n<div>else<\/div>\n<div>\u00a0 echo &#8220;$num1=$num2&#8221;<\/div>\n<div>fi<\/div>\n<div><\/div>\n<div>[root@shell \/server\/scripts]$ sh count3.sh<\/div>\n<div>\u8bf7\u8f93\u5165\u4e24\u4e2a\u6574\u6570: 12\u00a0 15<\/div>\n<div>12&lt;15<\/div>\n<h4>\u901a\u8fc7\u4e0d\u540c\u7684\u7cfb\u7edf\u7248\u672c\u53f7 \u5b89\u88c5\u4e0d\u540c\u7684YUM\u6e90<\/h4>\n<div>[root@shell \/server\/scripts]$ cat yum.sh<\/div>\n<div>#!\/bin\/bash<\/div>\n<div>#centos6\u548ccentos7\u83b7\u53d6\u5f53\u524d\u6587\u4ef6\u4e2d\u7684\u5217\u4e0d\u540c<\/div>\n<div>os_ver=`cat \/etc\/redhat-release |awk &#8216;{print $(NF-1)}&#8217;`<\/div>\n<div>if [ ${os_ver%%.*} -eq 7 ]<\/div>\n<div>then<\/div>\n<div>\u00a0 \u00a0 ping -c2 -W1 114.114.114.114 &amp;&gt;\/dev\/null<\/div>\n<div>\u00a0 \u00a0 if [ $? -ne 0 ];then<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0echo &#8220;\u7f51\u7edc\u4e0d\u901a\u6b63\u5728\u91cd\u542f\u7f51\u7edc\u8bf7\u7a0d\u540e&#8230;&#8230;&#8221;<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0systemctl restart network<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0ping -c2 -W1 114.114.114.114 &amp;&gt;\/dev\/null<\/div>\n<div>\u00a0 \u00a0[ $? -ne 0 ] &amp;&amp; echo &#8220;sendmail&#8230;&#8230;\u7ba1\u7406\u5458\u8bf7\u5c3d\u5feb\u68c0\u67e5\u670d\u52a1\u5668\u7684\u7f51\u7edc&#8221;<\/div>\n<div>\u00a0 \u00a0 fi<\/div>\n<div>\u00a0 \u00a0 if\u00a0 [ `rpm -qa wget|wc -l` -eq 0 ];then<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0 yum -y install wget &amp;&gt;\/dev\/null<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0 if\u00a0 [ $? -eq 0 ];then<\/div>\n<div>\u00a0 \u00a0 echo &#8220;wget \u5b89\u88c5\u6210\u529f&#8230;&#8230;.&#8221;<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0 else<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 echo &#8220;\u5b89\u88c5\u5931\u8d25 \u68c0\u67e5\u7f51\u7edc\u6216YUM\u6e90&#8230;..&#8221;<\/div>\n<div>\u00a0 fi<\/div>\n<div>\u00a0 \u00a0 fi<\/div>\n<div>\u00a0 \u00a0 wget -O \/etc\/yum.repos.d\/shell-epel.repo http:\/\/mirrors.aliyun.com\/repo\/epel-7.repo &amp;&gt;\/dev\/null<\/div>\n<div>\u00a0 \u00a0 if [ $? -eq 0 ];then<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0echo &#8220;YUM\u6e90\u66f4\u65b0\u6210\u529f&#8221;<\/div>\n<div>\u00a0 \u00a0 else<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0echo &#8220;YUM\u6e90\u66f4\u65b0\u4e0d\u6210\u529f \u53ef\u80fd\u662f\u7531\u4e8e\u7f51\u7edc\u5f15\u8d77&#8221;<\/div>\n<div>\u00a0 \u00a0 fi<\/div>\n<div>elif [ ${os_ver%%.*} -eq 6 ]<\/div>\n<div>then<\/div>\n<div>\u00a0 \u00a0 wget -O \/etc\/yum.repos.d\/shell-epel.repo http:\/\/mirrors.aliyun.com\/repo\/epel-6.repo<\/div>\n<div>else<\/div>\n<div>\u00a0 \u00a0 echo &#8220;\u8bf7\u68c0\u67e5\u60a8\u7684\u7cfb\u7edf\u7248\u672c&#8221;<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0 if [ $? -eq 0 ];then<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0echo &#8220;YUM\u6e90\u66f4\u65b0\u6210\u529f&#8221;<\/div>\n<div>\u00a0 \u00a0 else<\/div>\n<div>\u00a0 \u00a0 \u00a0 \u00a0echo &#8220;YUM\u6e90\u66f4\u65b0\u4e0d\u6210\u529f \u53ef\u80fd\u662f\u7531\u4e8e\u7f51\u7edc\u5f15\u8d77&#8221;<\/div>\n<div>\u00a0 \u00a0 fi<\/div>\n<div>fi<\/div>\n<h1>8.\u4e8c\u7ea7\u83dc\u5355<\/h1>\n<p>\u5728Shell\u811a\u672c\u4e2d\uff0c\u4e8c\u7ea7\u83dc\u5355\u662f\u6307\u4e00\u4e2a\u83dc\u5355\u7cfb\u7edf\u4e2d\u7684\u7b2c\u4e8c\u5c42\u83dc\u5355\uff0c\u901a\u5e38\u7528\u4e8e\u63d0\u4f9b\u66f4\u591a\u7684\u9009\u9879\u548c\u529f\u80fd\u3002\u4e8c\u7ea7\u83dc\u5355\u901a\u5e38\u5728\u7528\u6237\u9009\u62e9\u4e00\u7ea7\u83dc\u5355\u4e2d\u7684\u9009\u9879\u540e\u51fa\u73b0\uff0c\u4ee5\u4fbf\u7528\u6237\u8fdb\u4e00\u6b65\u7ec6\u5316\u4ed6\u4eec\u7684\u9009\u62e9\u3002<\/p>\n<p>\u5728Shell\u811a\u672c\u4e2d\u521b\u5efa\u4e8c\u7ea7\u83dc\u5355\u901a\u5e38\u4f7f\u7528\u5d4c\u5957\u7684case\u8bed\u53e5\u6216\u8005\u591a\u4e2aif-else\u8bed\u53e5\u6765\u5b9e\u73b0\u3002\u4e00\u822c\u60c5\u51b5\u4e0b\uff0c\u4e00\u7ea7\u83dc\u5355\u4f1a\u63d0\u793a\u7528\u6237\u9009\u62e9\u4e00\u4e2a\u9009\u9879\uff0c\u7136\u540e\u6839\u636e\u7528\u6237\u7684\u9009\u62e9\u8fdb\u5165\u76f8\u5e94\u7684\u4e8c\u7ea7\u83dc\u5355\u3002\u5728\u4e8c\u7ea7\u83dc\u5355\u4e2d\uff0c\u7528\u6237\u53ef\u4ee5\u518d\u6b21\u9009\u62e9\u4e00\u4e2a\u9009\u9879\uff0c\u7136\u540e\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\u6216\u8005\u8fdb\u5165\u66f4\u6df1\u5c42\u7684\u83dc\u5355\u3002<\/p>\n<p>\u4e8c\u7ea7\u83dc\u5355\u5728Shell\u811a\u672c\u4e2d\u901a\u5e38\u7528\u4e8e\u63d0\u4f9b\u66f4\u591a\u7684\u9009\u9879\u548c\u529f\u80fd\uff0c\u4f7f\u5f97\u811a\u672c\u66f4\u52a0\u7075\u6d3b\u548c\u4ea4\u4e92\u6027\u66f4\u5f3a\u3002\u5b83\u53ef\u4ee5\u7528\u4e8e\u7ba1\u7406\u591a\u4e2a\u9009\u9879\u548c\u7248\u672c\uff0c\u6267\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\uff0c\u6216\u8005\u8fdb\u4e00\u6b65\u7ec6\u5316\u7528\u6237\u7684\u9009\u62e9\u3002<\/p>\n<p>\u521b\u5efa\u4e00\u4e2a\u4e8c\u7ea7\u83dc\u5355\u9700\u8981\u8003\u8651\u7528\u6237\u8f93\u5165\u7684\u5408\u6cd5\u6027\uff0c\u4ee5\u53ca\u6839\u636e\u7528\u6237\u7684\u9009\u62e9\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\u3002\u5408\u7406\u8bbe\u8ba1\u548c\u5b9e\u73b0\u4e8c\u7ea7\u83dc\u5355\u53ef\u4ee5\u4f7fShell\u811a\u672c\u66f4\u52a0\u53cb\u597d\u548c\u6613\u7528<\/p>\n<h2>shell\u4e8c\u7ea7\u83dc\u5355case<\/h2>\n<p>\u5728Shell\u811a\u672c\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528case\u8bed\u53e5\u6765\u5b9e\u73b0\u4e8c\u7ea7\u83dc\u5355\u3002case\u8bed\u53e5\u5141\u8bb8\u4f60\u6839\u636e\u7528\u6237\u7684\u8f93\u5165\u8fdb\u884c\u591a\u4e2a\u9009\u9879\u7684\u5339\u914d\uff0c\u4ece\u800c\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\u3002<\/p>\n<p>\u4e0b\u9762\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u793a\u4f8b\uff0c\u6f14\u793a\u4e86\u5982\u4f55\u4f7f\u7528case\u8bed\u53e5\u5b9e\u73b0\u4e8c\u7ea7\u83dc\u5355\uff1a<\/p>\n<pre>echo \"Select an option:\"\r\necho \"1. Option 1\"\r\necho \"2. Option 2\"\r\nread FIRST_OPTION\r\n\r\ncase $FIRST_OPTION in\r\n  1)\r\n    echo \"You selected Option 1\"\r\n    # \u8fdb\u5165\u7b2c\u4e8c\u7ea7\u83dc\u5355\r\n    echo \"Select a sub-option:\"\r\n    echo \"a. Sub-option A\"\r\n    echo \"b. Sub-option B\"\r\n    read SUB_OPTION\r\n\r\n    case $SUB_OPTION in\r\n      a)\r\n        echo \"You selected Sub-option A\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Sub-option A\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      b)\r\n        echo \"You selected Sub-option B\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Sub-option B\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      *)\r\n        echo \"Invalid sub-option\"\r\n        ;;\r\n    esac\r\n    ;;\r\n  2)\r\n    echo \"You selected Option 2\"\r\n    # \u5728\u8fd9\u91cc\u6dfb\u52a0Option 2\u7684\u76f8\u5173\u4ee3\u7801\r\n    ;;\r\n  *)\r\n    echo \"Invalid option\"\r\n    ;;\r\nesac\r\n<\/pre>\n<p>\u5728\u4e0a\u9762\u7684\u793a\u4f8b\u4e2d\uff0c\u6839\u636e\u7528\u6237\u9009\u62e9\u7684\u7b2c\u4e00\u7ea7\u9009\u9879\uff0c\u8fdb\u5165\u4e86\u76f8\u5e94\u7684\u4e8c\u7ea7\u83dc\u5355\u3002\u5728\u4e8c\u7ea7\u83dc\u5355\u4e2d\uff0c\u4f7f\u7528\u4e86\u5d4c\u5957\u7684case\u8bed\u53e5\u6765\u5904\u7406\u7528\u6237\u7684\u8fdb\u4e00\u6b65\u9009\u62e9\u3002<\/p>\n<p>\u901a\u8fc7\u5408\u7406\u8bbe\u8ba1\u548c\u5d4c\u5957case\u8bed\u53e5\uff0c\u53ef\u4ee5\u5b9e\u73b0\u590d\u6742\u7684\u83dc\u5355\u7cfb\u7edf\uff0c\u63d0\u4f9b\u66f4\u591a\u9009\u9879\u548c\u529f\u80fd\uff0c\u4f7f\u5f97Shell\u811a\u672c\u66f4\u52a0\u7075\u6d3b\u548c\u4ea4\u4e92\u6027\u66f4\u5f3a\u3002<\/p>\n<h2>shell\u4e8c\u7ea7\u83dc\u5355if-else<\/h2>\n<p>\u5728Shell\u811a\u672c\u4e2d\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528\u591a\u4e2a\u5d4c\u5957\u7684if-else\u8bed\u53e5\u6765\u5b9e\u73b0\u4e8c\u7ea7\u83dc\u5355\u3002\u901a\u8fc7\u9010\u7ea7\u7684\u6761\u4ef6\u5224\u65ad\uff0c\u53ef\u4ee5\u8ba9\u7528\u6237\u5728\u4e0d\u540c\u7684\u9009\u9879\u4e0b\u8fdb\u5165\u4e0d\u540c\u7684\u4e8c\u7ea7\u83dc\u5355\u6216\u6267\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u793a\u4f8b\uff0c\u6f14\u793a\u4e86\u5982\u4f55\u4f7f\u7528if-else\u8bed\u53e5\u5b9e\u73b0\u4e8c\u7ea7\u83dc\u5355\uff1a<\/p>\n<pre>echo \"Select an option:\"\r\necho \"1. Option 1\"\r\necho \"2. Option 2\"\r\nread FIRST_OPTION\r\n\r\nif [ $FIRST_OPTION -eq 1 ]; then\r\n  echo \"You selected Option 1\"\r\n  # \u8fdb\u5165\u7b2c\u4e8c\u7ea7\u83dc\u5355\r\n  echo \"Select a sub-option:\"\r\n  echo \"a. Sub-option A\"\r\n  echo \"b. Sub-option B\"\r\n  read SUB_OPTION\r\n\r\n  if [ \"$SUB_OPTION\" = \"a\" ]; then\r\n    echo \"You selected Sub-option A\"\r\n    # \u5728\u8fd9\u91cc\u6dfb\u52a0Sub-option A\u7684\u76f8\u5173\u4ee3\u7801\r\n  elif [ \"$SUB_OPTION\" = \"b\" ]; then\r\n    echo \"You selected Sub-option B\"\r\n    # \u5728\u8fd9\u91cc\u6dfb\u52a0Sub-option B\u7684\u76f8\u5173\u4ee3\u7801\r\n  else\r\n    echo \"Invalid sub-option\"\r\n  fi\r\n\r\nelif [ $FIRST_OPTION -eq 2 ]; then\r\n  echo \"You selected Option 2\"\r\n  # \u5728\u8fd9\u91cc\u6dfb\u52a0Option 2\u7684\u76f8\u5173\u4ee3\u7801\r\n\r\nelse\r\n  echo \"Invalid option\"\r\nfi\r\n<\/pre>\n<p>\u5728\u4e0a\u9762\u7684\u793a\u4f8b\u4e2d\uff0c\u6839\u636e\u7528\u6237\u9009\u62e9\u7684\u7b2c\u4e00\u7ea7\u9009\u9879\uff0c\u901a\u8fc7\u591a\u4e2a\u5d4c\u5957\u7684if-else\u8bed\u53e5\u8fdb\u5165\u4e86\u76f8\u5e94\u7684\u4e8c\u7ea7\u83dc\u5355\u6216\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\u3002<\/p>\n<p>\u4f7f\u7528if-else\u8bed\u53e5\u5b9e\u73b0\u4e8c\u7ea7\u83dc\u5355\u540c\u6837\u53ef\u4ee5\u8fbe\u5230\u548ccase\u8bed\u53e5\u7c7b\u4f3c\u7684\u6548\u679c\uff0c\u53ea\u662f\u4ee3\u7801\u7ed3\u6784\u7565\u6709\u4e0d\u540c\u3002\u5408\u7406\u8bbe\u8ba1\u548c\u5d4c\u5957if-else\u8bed\u53e5\u540c\u6837\u53ef\u4ee5\u5b9e\u73b0\u590d\u6742\u7684\u83dc\u5355\u7cfb\u7edf\uff0c\u63d0\u4f9b\u66f4\u591a\u9009\u9879\u548c\u529f\u80fd\uff0c\u4f7f\u5f97Shell\u811a\u672c\u66f4\u52a0\u7075\u6d3b\u548c\u4ea4\u4e92\u6027\u66f4\u5f3a\u3002<\/p>\n<h2>f-else\u548ccase\u7684\u533a\u522b<\/h2>\n<p>\u5728Shell\u811a\u672c\u4e2d\uff0cif-else\u8bed\u53e5\u548ccase\u8bed\u53e5\u90fd\u7528\u4e8e\u8fdb\u884c\u6761\u4ef6\u5224\u65ad\u548c\u5206\u652f\u63a7\u5236\uff0c\u4f46\u5b83\u4eec\u5728\u8bed\u6cd5\u7ed3\u6784\u548c\u9002\u7528\u573a\u666f\u4e0a\u6709\u4e00\u4e9b\u533a\u522b\u3002<\/p>\n<h4>if-else\u8bed\u53e5\uff1a<\/h4>\n<p>\u7528\u4e8e\u5bf9\u6761\u4ef6\u8fdb\u884c\u9010\u4e00\u5224\u65ad\uff0c\u6839\u636e\u6761\u4ef6\u7684\u771f\u5047\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u5757\u3002<\/p>\n<p>\u9002\u7528\u4e8e\u9700\u8981\u8fdb\u884c\u590d\u6742\u7684\u6761\u4ef6\u5224\u65ad\uff0c\u6bcf\u4e2a\u6761\u4ef6\u53ef\u80fd\u662f\u4e00\u4e2a\u8868\u8fbe\u5f0f\uff0c\u53ef\u4ee5\u4f7f\u7528\u903b\u8f91\u8fd0\u7b97\u7b26\uff08\u5982&amp;&amp;\u3001||\uff09\u7ec4\u5408\u591a\u4e2a\u6761\u4ef6\u3002<\/p>\n<p>\u8bed\u6cd5\u7ed3\u6784\u8f83\u4e3a\u7075\u6d3b\uff0c\u53ef\u4ee5\u5904\u7406\u5404\u79cd\u590d\u6742\u7684\u6761\u4ef6\u903b\u8f91\u3002<\/p>\n<p>\u9002\u7528\u4e8e\u9700\u8981\u5bf9\u8303\u56f4\u3001\u5927\u5c0f\u5173\u7cfb\u7b49\u590d\u6742\u6761\u4ef6\u8fdb\u884c\u5224\u65ad\u7684\u60c5\u51b5\u3002<\/p>\n<h4>case\u8bed\u53e5\uff1a<\/h4>\n<p>\u7528\u4e8e\u6839\u636e\u4e00\u4e2a\u53d8\u91cf\u7684\u53d6\u503c\uff0c\u6267\u884c\u4e0e\u6bcf\u4e2a\u53d6\u503c\u76f8\u5173\u8054\u7684\u4ee3\u7801\u5757\u3002<\/p>\n<p>\u9002\u7528\u4e8e\u9700\u8981\u8fdb\u884c\u591a\u4e2a\u53d6\u503c\u7684\u7b80\u5355\u5339\u914d\uff0c\u6bcf\u4e2a\u53d6\u503c\u5bf9\u5e94\u4e00\u4e2a\u4ee3\u7801\u5757\u3002<\/p>\n<p>\u8bed\u6cd5\u7ed3\u6784\u7b80\u6d01\uff0c\u9002\u7528\u4e8e\u5904\u7406\u591a\u4e2a\u53d6\u503c\u7684\u60c5\u51b5\uff0c\u53ef\u4ee5\u4f7f\u5f97\u4ee3\u7801\u66f4\u52a0\u6e05\u6670\u548c\u6613\u8bfb\u3002<\/p>\n<p>\u9002\u7528\u4e8e\u5bf9\u591a\u4e2a\u79bb\u6563\u53d6\u503c\u8fdb\u884c\u5339\u914d\u7684\u60c5\u51b5\uff0c\u4f8b\u5982\u83dc\u5355\u9009\u62e9\u3001\u72b6\u6001\u5224\u65ad\u7b49\u3002<\/p>\n<p>\u603b\u7684\u6765\u8bf4\uff0cif-else\u8bed\u53e5\u9002\u7528\u4e8e\u590d\u6742\u7684\u6761\u4ef6\u5224\u65ad\uff0c\u800ccase\u8bed\u53e5\u9002\u7528\u4e8e\u5bf9\u591a\u4e2a\u79bb\u6563\u53d6\u503c\u8fdb\u884c\u5339\u914d\u3002\u5728\u5b9e\u9645\u7f16\u7a0b\u4e2d\uff0c\u6839\u636e\u5177\u4f53\u7684\u6761\u4ef6\u903b\u8f91\u548c\u9700\u6c42\uff0c\u53ef\u4ee5\u7075\u6d3b\u9009\u62e9\u4f7f\u7528if-else\u8bed\u53e5\u6216case\u8bed\u53e5\u3002<\/p>\n<h4>\u6848\u4f8b<\/h4>\n<pre>[root@shell \/server\/scripts]$ cat er.sh \r\n#!\/bin\/bash\r\n\r\n# \u4e00\u7ea7\u83dc\u5355\r\necho \"Select a service:\"\r\necho \"1. Nginx\"\r\necho \"2. PHP\"\r\necho \"3. Redis\"\r\necho \"4. MySQL\"\r\nread FIRST_OPTION\r\n\r\ncase $FIRST_OPTION in\r\n  1)\r\n    # \u4e8c\u7ea7\u83dc\u5355 - Nginx\r\n    echo \"Select a version of Nginx:\"\r\n    echo \"a. Nginx 1.18\"\r\n    echo \"b. Nginx 1.20\"\r\n    echo \"c. Nginx 1.22\"\r\n    read NGINX_OPTION\r\n\r\n    case $NGINX_OPTION in\r\n      a)\r\n        echo \"You selected Nginx 1.18\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Nginx 1.18\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      b)\r\n        echo \"You selected Nginx 1.20\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Nginx 1.20\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      c)\r\n        echo \"You selected Nginx 1.22\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Nginx 1.22\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      *)\r\n        echo \"Invalid option\"\r\n        ;;\r\n    esac\r\n    ;;\r\n  2)\r\n    # \u4e8c\u7ea7\u83dc\u5355 - PHP\r\n    echo \"Select a version of PHP:\"\r\n    echo \"x. PHP 7.3\"\r\n    echo \"y. PHP 7.4\"\r\n    echo \"z. PHP 8.0\"\r\n    read PHP_OPTION\r\n\r\n    case $PHP_OPTION in\r\n      x)\r\n        echo \"You selected PHP 7.3\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0PHP 7.3\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      y)\r\n        echo \"You selected PHP 7.4\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0PHP 7.4\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      z)\r\n        echo \"You selected PHP 8.0\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0PHP 8.0\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      *)\r\n        echo \"Invalid option\"\r\n        ;;\r\n    esac\r\n    ;;\r\n  3)\r\n    # \u4e8c\u7ea7\u83dc\u5355 - Redis\r\n    echo \"Select a version of Redis:\"\r\n    echo \"m. Redis 5.0\"\r\n    echo \"n. Redis 6.0\"\r\n    echo \"o. Redis 6.2\"\r\n    read REDIS_OPTION\r\n\r\n    case $REDIS_OPTION in\r\n      m)\r\n        echo \"You selected Redis 5.0\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Redis 5.0\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      n)\r\n        echo \"You selected Redis 6.0\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Redis 6.0\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      o)\r\n        echo \"You selected Redis 6.2\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0Redis 6.2\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      *)\r\n        echo \"Invalid option\"\r\n        ;;\r\n    esac\r\n    ;;\r\n  4)\r\n    # \u4e8c\u7ea7\u83dc\u5355 - MySQL\r\n    echo \"Select a version of MySQL:\"\r\n    echo \"p. MySQL 5.7\"\r\n    echo \"q. MySQL 8.0\"\r\n    echo \"r. MySQL 8.0\"\r\n    read MYSQL_OPTION\r\n\r\n    case $MYSQL_OPTION in\r\n      p)\r\n        echo \"You selected MySQL 5.7\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0MySQL 5.7\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      q)\r\n        echo \"You selected MySQL 8.0\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0MySQL 8.0\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      r)\r\n        echo \"You selected MySQL 8.0\"\r\n        # \u5728\u8fd9\u91cc\u6dfb\u52a0MySQL 8.0\u7684\u76f8\u5173\u4ee3\u7801\r\n        ;;\r\n      *)\r\n        echo \"Invalid option\"\r\n        ;;\r\n    esac\r\n    ;;\r\n  *)\r\n    echo \"Invalid option\"\r\n    ;;\r\nesac\r\n<\/pre>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>1.if\u7684\u57fa\u672c\u8bed\u6cd5 if\u4e0e[\u4e4b\u95f4\u8981\u6709\u7a7a\u683c []\u4e0e\u5224\u65ad\u6761\u4ef6\u4e4b\u95f4\u4e5f\u5fc5\u987b\u6709\u7a7a\u683c ]\u4e0e;\u4e4b\u95f4\u4e0d\u80fd\u6709\u7a7a\u683c 2.\u5bf9\u5b57\u7b26\u4e32\u7684 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[25],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=\/wp\/v2\/posts\/1278"}],"collection":[{"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1278"}],"version-history":[{"count":13,"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=\/wp\/v2\/posts\/1278\/revisions"}],"predecessor-version":[{"id":1349,"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=\/wp\/v2\/posts\/1278\/revisions\/1349"}],"wp:attachment":[{"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1278"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1278"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.qiangzhenshuai.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1278"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}