{"id":8902,"date":"2023-09-07T12:05:57","date_gmt":"2023-09-07T04:05:57","guid":{"rendered":"\/?p=8902"},"modified":"2023-09-07T12:05:57","modified_gmt":"2023-09-07T04:05:57","slug":"linux%e7%8e%af%e5%a2%83%e5%8f%98%e9%87%8f%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"\/?p=8902","title":{"rendered":"Linux\u73af\u5883\u53d8\u91cf\u8be6\u89e3"},"content":{"rendered":"<h1>Linux\u73af\u5883\u53d8\u91cf\u8be6\u89e3<\/h1>\n<h2>1. \u751f\u6548\u65f6\u673a<\/h2>\n<p>\u4e0e\u73af\u5883\u53d8\u91cf\u6709\u5173\u7684\u56db\u4e2a\u6587\u4ef6<\/p>\n<ul>\n<li>\n<p><code>\/etc\/profile<\/code><\/p>\n<\/li>\n<li>\n<p><code>\/etc\/bashrc<\/code><\/p>\n<\/li>\n<li>\n<p><code>~\/.bash_profile<\/code><\/p>\n<\/li>\n<li>\n<p><code>~\/.bashrc<\/code><\/p>\n<\/li>\n<\/ul>\n<p>\u672c\u7bc7\u6587\u7ae0\u5b9e\u9a8c\u6bd4\u8f83\u591a, \u6b65\u9aa4\u6709\u70b9\u590d\u6742, \u8fd9\u91cc\u5148\u8bf4\u7ed3\u8bba<\/p>\n<table>\n<thead>\n<tr>\n<th style=\"text-align: left;\">\u6267\u884c\u65b9\u5f0f<\/th>\n<th style=\"text-align: center;\">profile<\/th>\n<th style=\"text-align: center;\">bashrc<\/th>\n<th style=\"text-align: center;\">\u793a\u4f8b<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"text-align: left;\">\u975e\u4ea4\u4e92\u5f0f\u4e14\u975e\u767b\u5f55shell<\/td>\n<td style=\"text-align: center;\">\u4e0d\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\">\u4e0d\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\"><code>crontab<\/code>\u4e2d\u6267\u884c\u7684bash\u811a\u672c<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left;\">\u975e\u4ea4\u4e92\u5f0f\u767b\u5f55shell<\/td>\n<td style=\"text-align: center;\">\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\">\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\"><code>crontab<\/code>\u4e2d\u901a\u8fc7<code>su -l<\/code>\u6267\u884c\u7684\u811a\u672c<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left;\">\u4ea4\u4e92\u5f0f\u975e\u767b\u5f55shell<\/td>\n<td style=\"text-align: center;\">\u4e0d\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\">\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\">\u5982\u547d\u4ee4\u884c\u4e2d\u901a\u8fc7<code>su \u7528\u6237\u540d<\/code>\u6267\u884c\u7684\u547d\u4ee4<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left;\">\u4ea4\u4e92\u5f0f\u767b\u5f55shell<\/td>\n<td style=\"text-align: center;\">\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\">\u52a0\u8f7d<\/td>\n<td style=\"text-align: center;\">\u666e\u901a\u7684\u7ec8\u7aef\u767b\u5f55, ssh\u8fdc\u7a0b\u767b\u5f55, \u4ee5\u53ca\u4f7f\u7528<code>su - l \u7528\u6237\u540d<\/code>\u5207\u6362\u8eab\u4efd\u7b49<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>1.1 \u7406\u8bba\u57fa\u7840<\/h3>\n<p>\u9996\u5148\u8ba4\u8bc6\u4e00\u4e0b\u767b\u5f55shell\u4e0e\u975e\u767b\u5f55shell, \u4ea4\u4e92\u5f0fshell\u4e0e\u975e\u4ea4\u4e92\u5f0fshell.<\/p>\n<h4>1.1.1 \u767b\u5f55(login)\u4e0e\u975e\u767b\u5f55(nologin)<\/h4>\n<p>\u666e\u901a\u7684\u7ec8\u7aef\u767b\u5f55, ssh\u8fdc\u7a0b\u767b\u5f55, \u6216\u8005\u662f<code>su -l \u7528\u6237\u540d<\/code>\u5207\u6362\u7528\u6237\u7b49, \u5305\u542b\u7684\u767b\u5f55\u884c\u4e3a, \u79f0\u6253\u5f00\u7684\u7ec8\u7aef\u7c7b\u578b\u4e3a<strong>\u767b\u5f55\u5f0fshell<\/strong>, \u9664\u4e86\u8bfb\u53d6<code>profile<\/code>, \u8fd8\u4f1a\u8bfb\u53d6<code>bashrc<\/code>;<\/p>\n<p>\u4e0e\u4e4b\u76f8\u5bf9\u7684, \u5728\u6253\u5f00\u7684\u7ec8\u7aef\u4e2d\u6267\u884c<code>bash<\/code>\u547d\u4ee4\u5f97\u5230\u65b0\u7684shell\u4f1a\u8bdd, \u8fd8\u6709\u4f7f\u7528<code>su \u7528\u6237\u540d<\/code>\u5207\u6362\u7528\u6237\u7684\u64cd\u4f5c\u521b\u5efa\u7684\u7ec8\u7aef, \u4ee5\u53ca\u6267\u884c\u811a\u672c\u65f6\u521b\u5efa\u7684bash\u8fdb\u7a0b, \u90fd\u662f<strong>\u975e\u767b\u5f55\u5f0fshell<\/strong>.<\/p>\n<p>~\u9700\u8981\u6ce8\u610f\u7684\u662f, \u4ece\u684c\u9762\u53d1\u884c\u7248\u56fe\u5f62\u754c\u9762\u767b\u5f55, \u6216\u662f\u901a\u8fc7VNC\u767b\u5f55\u884c\u4e3a, \u90fd\u662f<strong>\u975e\u767b\u5f55\u5f62\u5f0f<\/strong>~. \u7ecf\u8fc7\u5b9e\u9a8c, \u89c9\u5f97\u8fd9\u53e5\u8bdd\u5e76\u6b63\u786e, \u70b9\u51fb\u767b\u5f55\u6309\u94ae\u65f6, \u684c\u9762\u7a0b\u5e8f\u4f1a\u52a0\u8f7d<code>\/etc\/profile<\/code>\u6587\u4ef6, \u89c1\u4e0b\u9762\u7684\u5b9e\u9a8c.<\/p>\n<h4>1.1.2 \u4ea4\u4e92\u5f0f\u4e0e\u975e\u4ea4\u4e92\u5f0f<\/h4>\n<p><strong>\u4ea4\u4e92\u5f0f\u6a21\u5f0f<\/strong>: \u5c31\u662fshell\u7b49\u5f85\u7528\u6237\u8f93\u5165\uff0c\u5e76\u4e14\u6267\u884c\u7528\u6237\u952e\u5165\u7684\u547d\u4ee4. \u6b64\u65f6shell\u4e0e\u7528\u6237\u8fdb\u884c\u4ea4\u4e92, \u8f93\u5165\u8f93\u51fa\u4e0e\u7ec8\u7aef\u76f8\u8fde. \u8fd9\u79cd\u6a21\u5f0f\u4e5f\u662f\u5927\u591a\u6570\u7528\u6237\u975e\u5e38\u719f\u6089\u7684: \u7ec8\u7aef\u767b\u5f55\u3001\u6267\u884c\u4e00\u4e9b\u547d\u4ee4\u3001\u9000\u51fa. \u9000\u51fa\u540e, shell\u4e5f\u968f\u4e4b\u7ec8\u6b62.<\/p>\n<p><strong>\u975e\u4ea4\u4e92\u5f0f\u6a21\u5f0f<\/strong>: shell\u4e0d\u4e0e\u7528\u6237\u8fdb\u884c\u4ea4\u4e92\uff0c\u800c\u662f\u8bfb\u53d6\u5b58\u653e\u5728\u6587\u4ef6\u4e2d\u7684\u547d\u4ee4, \u5e76\u4e14\u6267\u884c. \u5f53\u5b83\u8bfb\u5230\u6587\u4ef6\u7684\u7ed3\u5c3e\uff0cshell\u4e5f\u5c31\u7ec8\u6b62\u4e86. \u5178\u578b\u7684\u4f8b\u5b50\u5c31\u662f<code>crontab<\/code>\u5b9a\u65f6\u6267\u884c\u811a\u672c, \u5b83\u4eec\u7684\u8f93\u5165\u8f93\u51fa\u4e0d\u4f1a\u4e0e\u4efb\u4f55bash\u8fdb\u7a0b\u76f8\u8fde\u63a5.<\/p>\n<p>\u5b83\u4eec\u4e4b\u95f4\u53ef\u4ee5\u76f8\u4e92\u7ec4\u5408, \u6240\u4ee5\u4e00\u5171\u67094\u79cd\u60c5\u51b5.<\/p>\n<h3>1.2 \u5b9e\u9a8c\u9a8c\u8bc1<\/h3>\n<h4>1.2.1 \u9a8c\u8bc1\u767b\u5f55\u5f0f\u4e0e\u975e\u767b\u5f55\u5f0fshell<\/h4>\n<p>\u5b9e\u9a8c\u5982\u4e0b\u64cd\u4f5c<\/p>\n<pre><code>[root@localhost ~]# echo &#039;usual_var=123456&#039; &gt;&gt; \/etc\/profile\n[root@localhost ~]# echo $usual_var\n\n## \u5207\u6362\u4e3a\u666e\u901a\u7528\u6237, \u975e\u767b\u5f55shell\n[root@localhost ~]# su general\n[general@localhost root]$ echo $usual_var\n\n[general@localhost root]$ exit\nexit\n[root@localhost ~]# echo $usual_var\n\n[root@localhost ~]# su -l general\nLast login: Sun Dec 11 20:01:46 PST 2016 on pts\/1\n[general@localhost ~]$ echo $usual_var\n123456\n[general@localhost ~]$ exit\nlogout\n[root@localhost ~]# echo $usual_var\n<\/code><\/pre>\n<p>\u53ef\u4ee5\u770b\u51fa<code>ssh<\/code>\u547d\u4ee4\u7684<code>-l<\/code>\u9009\u9879\u7684\u4f5c\u7528, \u5c31\u662f\u5f00\u542f\u4e00\u4e2a\u6b63\u5e38\u7684\u767b\u5f55shell\u4f1a\u8bdd. \u540c\u65f6\u4e5f\u9a8c\u8bc1\u4e86, <code>profile<\/code>\u6587\u4ef6\u9700\u8981\u662f\u767b\u5f55shell\u624d\u80fd\u52a0\u8f7d\u7684.<\/p>\n<p>\u7ee7\u7eed\u8fdb\u884c, \u5728\u5f53\u524d\u7ec8\u7aef\u6267\u884c<code>bash<\/code>\u547d\u4ee4, \u4f1a\u6253\u5f00\u4e00\u4e2a\u65b0\u7684shell, \u8fd9\u4e5f\u662f\u4e00\u4e2a\u975e\u767b\u5f55\u5f0fshell.<\/p>\n<pre><code>[root@localhost ~]# echo &#039;usual_var=123456&#039; &gt;&gt; \/etc\/profile\n[root@localhost ~]# echo $usual_var\n\n[root@localhost ~]# bash\n[root@localhost ~]# echo $usual_var\n<\/code><\/pre>\n<p>\u53ef\u89c1, <code>bash<\/code>\u4e0e<code>su<\/code>\u90fd\u6ca1\u6709\u91cd\u65b0\u52a0\u8f7d<code>profile<\/code>\u6587\u4ef6.<\/p>\n<p>\u5c06<code>usual_var<\/code>\u53d8\u91cf\u5199\u5165\u5230<code>bashrc<\/code>\u6587\u4ef6, \u518d\u6267\u884c\u4e0a\u8ff0\u7c7b\u4f3c\u64cd\u4f5c, \u4f60\u4f1a\u53d1\u73b0<code>bash<\/code>, <code>su<\/code>\u4e0e<code>su -l<\/code>\u4e09\u79cd\u884c\u4e3a\u90fd\u4f1a\u52a0\u8f7d<code>bashrc<\/code>, \u8fd9\u91cc\u4e0d\u518d\u5217\u51fa.<\/p>\n<blockquote>\n<p>\u6ce8\u610fbash\u547d\u4ee4\u52a0\u8f7d\u7684\u662f\u5f53\u524d\u7528\u6237\u7684<code>~\/.bashrc<\/code>, \u800c<code>su<\/code>\u64cd\u4f5c\u52a0\u8f7d\u7684\u662f\u76ee\u6807\u7528\u6237\u7684<code>~\/.bashrc<\/code>.<\/p>\n<\/blockquote>\n<h4>1.2.2 crontab\u7684\u975e\u4ea4\u4e92\u5f0f\u5c5e\u6027<\/h4>\n<p>\u6211\u4eec\u90fd\u80fd\u7406\u89e3, \u901a\u8fc7<code>crontab<\/code>\u6267\u884c\u7684\u811a\u672c, \u8f93\u5165\u8f93\u51fa\u4e0d\u4e0e\u7279\u5b9a\u7ec8\u7aef\u76f8\u8fde, \u6240\u4ee5\u88ab\u79f0\u4e3a<strong>\u975e\u4ea4\u4e92\u5f0fshell<\/strong>. \u4e0b\u9762\u6211\u4eec\u9a8c\u8bc1\u4e00\u4e0b, \u4f7f\u7528<code>crontab<\/code>\u6267\u884c\u5b9a\u65f6\u4efb\u52a1\u65f6, \u4efb\u52a1\u811a\u672c\u5bf9\u4e24\u79cd\u6587\u4ef6\u7684\u52a0\u8f7d\u60c5\u51b5.<\/p>\n<p>\u5728<code>\/etc\/profile<\/code>\u4e2d\u6dfb\u52a0\u73af\u5883\u53d8\u91cf<code>env_var<\/code>.<\/p>\n<pre><code>$ echo &#039;export env_var=abcdef&#039; &gt;&gt; \/etc\/profile\n<\/code><\/pre>\n<p>\u5efa\u7acb\u5b9e\u9a8c\u7528\u7684\u4efb\u52a1\u811a\u672c<code>nointeract.sh<\/code><\/p>\n<pre><code>$ cat \/tmp\/nointeract.sh\n#!\/bin\/bash\necho $env_var &gt;&gt; \/tmp\/var_result\n<\/code><\/pre>\n<p>\u5efa\u7acb<code>crontab<\/code>\u4efb\u52a1, \u6bcf10s\u6267\u884c1\u6b21.<\/p>\n<pre><code>$ crontab -e\n* * * * * sleep 10; \/bin\/bash \/tmp\/nointeract.sh\n* * * * * sleep 20; \/bin\/bash \/tmp\/nointeract.sh\n* * * * * sleep 30; \/bin\/bash \/tmp\/nointeract.sh\n* * * * * sleep 40; \/bin\/bash \/tmp\/nointeract.sh\n* * * * * sleep 50; \/bin\/bash \/tmp\/nointeract.sh\n<\/code><\/pre>\n<p>\u2026\u7b49\u5f8510s\u540e, \u67e5\u770b<code>\/tmp\/var_result<\/code>\u6587\u4ef6, \u662f\u7a7a\u7684, \u8bf4\u660e\u4efb\u52a1\u811a\u672c\u6ca1\u6709\u8bfb\u53d6\u5230<code>\/etc\/profile<\/code>. \u7136\u540e\u628a<code>env_var<\/code>\u53d8\u91cf\u5199\u5230<code>bashrc<\/code>\u6587\u4ef6\u4e2d, 10s\u540e<code>var_result<\/code>\u4f9d\u7136\u6587\u4ef6\u7684\u8f93\u51fa\u4f9d\u7136\u4e3a\u7a7a.<\/p>\n<p>\u8bf4\u660e<strong>\u975e\u4ea4\u4e92shell\u4e14\u975e\u767b\u5f55\u5f62\u5f0f\u7684bash\u8fdb\u7a0b\u4e0d\u4f1a\u52a0\u8f7d<code>profile<\/code>\u4e5f\u4e0d\u4f1a\u52a0\u8f7d<code>bashrc<\/code><\/strong>.<\/p>\n<hr \/>\n<p>\u5148\u5c06\u4e0a\u9762\u5199\u5165\u5230<code>bashrc<\/code>\u7684<code>env_var<\/code>\u53d8\u91cf\u5220\u9664, \u53ea\u4fdd\u7559<code>profile<\/code>, \u7136\u540e\u4fee\u6539<code>crontab<\/code>\u4efb\u52a1\u5217\u8868, \u5185\u5bb9\u5982\u4e0b<\/p>\n<pre><code>* * * * * sleep 10; su -l root -c &#039;\/bin\/bash \/tmp\/nointeract.sh&#039;\n* * * * * sleep 20; su -l root -c &#039;\/bin\/bash \/tmp\/nointeract.sh&#039;\n* * * * * sleep 30; su -l root -c &#039;\/bin\/bash \/tmp\/nointeract.sh&#039;\n* * * * * sleep 40; su -l root -c &#039;\/bin\/bash \/tmp\/nointeract.sh&#039;\n* * * * * sleep 50; su -l root -c &#039;\/bin\/bash \/tmp\/nointeract.sh&#039;\n<\/code><\/pre>\n<p>\u7136\u540e, <code>\/tmp\/var_result<\/code>\u5c31\u6709\u8f93\u51fa\u4e86, \u7684\u786e\u662f<code>profile<\/code>\u6587\u4ef6\u4e2d\u5b9a\u4e49\u7684<code>env_var<\/code>\u7684\u503c.<\/p>\n<p>\u4fdd\u7559<code>crontab<\/code>, \u5c06<code>env_var<\/code>\u4ece<code>profile<\/code>\u6587\u4ef6\u4e2d\u79fb\u9664, \u6dfb\u52a0\u5230<code>bashrc<\/code>\u4e2d, \u89c2\u5bdf<code>\/tmp\/var_result<\/code>\u7684\u8f93\u51fa, \u4e5f\u80fd\u5f97\u5230<code>env_var<\/code>\u7684\u503c.<\/p>\n<p>\u8bf4\u660e\u975e\u4ea4\u4e92\u5f0f\u767b\u5f55shell\u53ef\u4ee5\u540c\u65f6\u52a0\u8f7d<code>profile<\/code>\u4e0e<code>bashrc<\/code>\u6587\u4ef6.<\/p>\n<h4>1.2.3 \u56fe\u5f62\u754c\u9762\u7684\u975e\u767b\u5f55\u5c5e\u6027<\/h4>\n<p>\u4e3a\u4e86\u9a8c\u8bc1\u8fd9\u4e00\u70b9, \u9700\u8981\u6709\u4e24\u53f0\u4e3b\u673a, \u5206\u522b\u4ee5A\u548cB\u6307\u4ee3, A\u662f\u62e5\u6709\u56fe\u5f62\u754c\u9762\u7684\u684c\u9762\u53d1\u884c\u7248.<\/p>\n<p>\u6211\u4eec\u5728\u4e3b\u673aA\u7684<code>\/etc\/profile<\/code>\u6587\u4ef6\u5199\u5165\u4ee5\u4e0b\u5185\u5bb9. (\u4e3b\u673aA\u662fFedora 24\u7684\u684c\u9762\u53d1\u884c\u7248)<\/p>\n<pre><code>for i in {0..100};\ndo\n    ping -c 1 \u4e3b\u673aB\u7684IP\u5730\u5740\n    sleep 1\ndone\n<\/code><\/pre>\n<p>\u91cd\u542f\u4e3b\u673aA, \u4e0d\u505a\u4efb\u4f55\u767b\u5f55\u64cd\u4f5c, \u6211\u4eec\u5728\u4e3b\u673a\u6293\u53d6\u6765\u81ea\u4e3b\u673aA\u7684ICMP\u5305<code>tcpdump -i eth0 src \u4e3b\u673aA\u7684IP and dst \u4e3b\u673aB\u7684IP<\/code>. \u6ca1\u6709\u4efb\u4f55\u53cd\u5e94.<\/p>\n<p>\u7136\u540e, \u5728\u4e3b\u673aA\u7684\u56fe\u5f62\u754c\u9762\u767b\u5f55, \u5c06\u4f1a\u5f97\u5230100\u79d2\u7684\u9ed1\u5c4f, \u5728\u8fd9\u671f\u95f4, \u4e3b\u673aB\u4e0a\u53ef\u4ee5\u6293\u53d6\u5230\u6765\u81eaA\u7684ping\u5305. \u8bf4\u660e\u5728\u8fd9\u6bb5\u65f6\u95f4\u4e3b\u673aA\u5728\u52a0\u8f7d<code>\/etc\/profile<\/code>\u7684\u5185\u5bb9, \u5e76\u4e14\u9700\u8981\u7b49\u5230\u5176\u6267\u884c\u5b8c\u6210\u624d\u8fdb\u884c\u4e0b\u4e00\u6b65\u64cd\u4f5c.<\/p>\n<p>\u8fd8\u6ca1\u5b8c, \u5728\u4e3b\u673aA\u7684\u56fe\u5f62\u754c\u9762\u9ed1\u5c4f\u671f\u95f4, \u6211\u4eec\u5c1d\u8bd5\u4f7f\u7528ssh\u8fde\u63a5\u5230\u4e3b\u673aA, \u521a\u5b8c\u6210\u767b\u5f55, \u7ec8\u7aef\u754c\u9762\u5c31\u6253\u5370\u51faping\u64cd\u4f5c\u7684\u7ed3\u679c, \u8bf4\u660e\u8fd9\u4e2a\u65b0\u521b\u5efa\u7684bash\u8fdb\u7a0b\u4e5f\u5c1d\u8bd5\u52a0\u8f7d\u5e76\u6267\u884c\u4e86<code>\/etc\/profile<\/code>\u6587\u4ef6( \u4e0d\u540c\u4e8e\u56fe\u5f62\u754c\u9762\u5b8c\u5168\u963b\u585e\u7684\u9ed1\u5c4f\u72b6\u6001, \u5728ssh\u754c\u9762\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528Ctrl+C\u53d6\u6d88\u6b64ping\u64cd\u4f5c\u7684\u6267\u884c), \u8fd9\u5f88\u6b63\u5e38.<\/p>\n<p>\u5728ssh\u767b\u5f55\u7684shell\u4e2d\u6267\u884c\u67e5\u8be2<\/p>\n<pre><code>$ ps aux | grep bash\ngeneral    7056  0.0  0.0 119904     8 tty2     S+   22:37   0:00 -\/bin\/bash -c gnome-session\nroot      23738  0.0  0.1 120708  4376 pts\/0    Ss   22:42   0:00 -bash\nroot      32895  0.0  0.0 117140  1032 pts\/0    R+   22:51   0:00 grep --color=auto bash\n<\/code><\/pre>\n<p>\u4e5f\u5c31\u662f\u8bf4, \u56fe\u5f62\u754c\u9762\u5176\u5b9e\u4e5f\u662f\u7531bash\u8fdb\u7a0b\u542f\u52a8\u7684. \u4f46\u5728\u672a\u767b\u5f55\u9636\u6bb5, <code>\/etc\/profile<\/code>\u5e76\u672a\u8d77\u4f5c\u7528.<\/p>\n<p>\u7b49\u5f85\u56fe\u5f62\u754c\u9762\u9ed1\u5c4f\u7ed3\u675f, \u5728ssh\u7ec8\u7aef\u4e2d, \u518d\u6b21\u67e5\u627e<code>bash<\/code>\u8fdb\u7a0b, \u5c31\u53ea\u5269\u4e0b\u81ea\u5df1\u4e86. \u505c\u7559\u5728\u56fe\u5f62\u754c\u9762\u65f6, \u6ca1\u6709\u5f00\u542fbash\u8fdb\u7a0b. \u4f46\u662f\u5f53\u6253\u5f00&quot;\u7ec8\u7aef&quot;\u7a0b\u5e8f\u65f6, \u5c31\u4f1a\u81ea\u52a8\u4ee5\u5f53\u524d\u7528\u6237\u5efa\u7acb<strong>\u4ea4\u4e92\u5f0f\u767b\u5f55shell<\/strong>.<\/p>\n<blockquote>\n<p><code>\/etc\/profile<\/code>\u4e0e&quot;\u5f00\u673a\u542f\u52a8&quot;\u8fd9\u79cd\u64cd\u4f5c\u6ca1\u6709\u4efb\u4f55\u5173\u7cfb, \u4e0d\u8981\u628a\u5f00\u673a\u542f\u52a8\u9879\u5199\u5728\u8fd9\u91cc, \u6ca1\u7528\u7684.<\/p>\n<\/blockquote>\n<h2>2. \u52a0\u8f7d\u987a\u5e8f<\/h2>\n<p>\u975e\u4ea4\u4e92\u5f0f\u975e\u767b\u5f55shell\u6bd4\u8f83\u597d\u8bf4, \u54ea\u4e00\u4e2a\u90fd\u4e0d\u52a0\u8f7d\u2026<\/p>\n<p>\u4ea4\u4e92\u5f0f\u975e\u767b\u5f55shell\u4e5f\u6bd4\u8f83\u597d\u8bf4, \u4e5f\u5c31\u662f<code>\/etc\/bashrc<\/code> -&gt; <code>~\/.bashrc<\/code>, \u540e\u8005\u8986\u76d6\u524d\u8005.<\/p>\n<p>\u4e24\u79cd\u767b\u5f55\u5f0fshell\u4e24\u79cd\u6587\u4ef6\u90fd\u4f1a\u52a0\u8f7d, \u4e00\u822c\u662f<\/p>\n<p><code>\/etc\/bashrc<\/code> -&gt; <code>~\/.bashrc<\/code>,<\/p>\n<p><code>\/etc\/profile<\/code> -&gt; <code>~\/.bash_profile<\/code>.<\/p>\n<p>\u4e0d\u8fc7<code>\/etc\/bashrc<\/code> -&gt; <code>~\/.bash_profile<\/code>, \u603b\u662f\u7528\u6237\u7ea7\u914d\u7f6e\u4f18\u5148\u7ea7\u66f4\u9ad8. \u6240\u4ee5\u6700\u7ec8\u52a0\u8f7d\u987a\u5e8f\u53ef\u4ee5\u770b\u6210\u662f<\/p>\n<p><code>\/etc\/profile<\/code> -&gt; <code>\/etc\/bashrc<\/code> -&gt; <code>~\/.bash_profile<\/code> -&gt; <code>~\/.bashrc<\/code>.<\/p>\n<p>Linux\u73af\u5883\u53d8\u91cf\u89e3\u67902-\u53d8\u91cf\u4f5c\u7528\u57df\u53ca\u751f\u547d\u5468\u671f<\/p>\n<ol>\n<li>\n<p>abc=123<\/p>\n<\/li>\n<li>\n<p>abc=123 &amp;&amp; set -a abc<\/p>\n<\/li>\n<li>\n<p>export abc=123<\/p>\n<\/li>\n<li>\n<p>declare abc=123<\/p>\n<\/li>\n<li>\n<p>declare -x abc=123<\/p>\n<\/li>\n<li>\n<p>env abc=123<\/p>\n<\/li>\n<\/ol>\n<p>\u5176\u4e2d, 1\u548c4\u7684\u6548\u679c\u76f8\u540c, 2,3\u548c5\u7684\u6548\u679c\u76f8\u540c.<\/p>\n<p>1,4\u53ea\u662f\u5728\u5f53\u524dbash\u8fdb\u7a0b\u4e2d\u8bbe\u7f6e\u53d8\u91cf, \u65e0\u6cd5\u5f71\u54cd\u5230\u5176\u4ed6bash\u8fdb\u7a0b, \u65e0\u8bba\u662f\u5b50bash\u8fdb\u7a0b, \u7236bash\u8fdb\u7a0b\u8fd8\u662f\u540c\u7ea7\u7684\u65b0\u521b\u5efa\u7684bash\u8fdb\u7a0b. \u8fd9\u91cc\u79f0\u8fd9\u79cd\u53d8\u91cf\u4e3a<strong>\u666e\u901a\u53d8\u91cf<\/strong>, \u4e5f\u88ab\u79f0\u4e3a<strong>bash\u53d8\u91cf<\/strong>.<\/p>\n<p>\u901a\u8fc72,3,5\u65b9\u5f0f\u521b\u5efa\u7684\u53d8\u91cf, \u5728\u540c\u4e00\u7528\u6237, \u5e76\u4e14\u5c5e\u4e8e\u5f53\u524dbash\u8fdb\u7a0b\u7684\u5b50\u7ea7\u8fdb\u7a0b\u4e2d\u6709\u6548. \u5373\u901a\u8fc7\u5f53\u524dbash shell\u4ee5\u8fd9\u51e0\u79cd\u65b9\u6cd5\u521b\u5efa\u7684\u53d8\u91cf, \u53ef\u4ee5\u4f20\u9012\u7ed9\u6240\u6709\u5728\u5f53\u524dbash, \u4ee5\u540c\u4e00\u7528\u6237\u8eab\u4efd\u542f\u52a8\u7684\u8fdb\u7a0b\u4e2d. \u4f46\u5bf9\u4e8e\u7236\u7ea7bash\u8fdb\u7a0b\u548c\u540c\u7ea7bash\u8fdb\u7a0b\u65e0\u6548. \u8fd9\u79cd\u53d8\u91cf\u79f0\u4e3a<strong>\u7528\u6237\u53d8\u91cf<\/strong>.<\/p>\n<h2>\u53d8\u91cf\u4f5c\u7528\u57df\u5206\u6790<\/h2>\n<h3>bash\u53d8\u91cf<\/h3>\n<h4>\u793a\u4f8b1<\/h4>\n<p>\u5f53\u524dbash\u4e2d\u5b9a\u4e49\u7684\u666e\u901a\u53d8\u91cf, \u65e0\u6cd5\u4f20\u9012\u5230\u5b50bash\u8fdb\u7a0b.<\/p>\n<pre><code>$ cat test.sh\n#!\/bin\/bash\necho &#039;begin&#039;\necho $abc\necho &#039;end&#039;\n$ abc=123\n$ echo $abc\n123\n$ .\/test.sh\nbegin\n\nend\n<\/code><\/pre>\n<h4>\u793a\u4f8b2<\/h4>\n<p>\u5f53\u524dbash\u4e2d\u5b9a\u4e49\u7684\u666e\u901a\u53d8\u91cf, \u4e5f\u65e0\u6cd5\u5f71\u54cd\u5230\u7236\u7ea7bash\u8fdb\u7a0b.<\/p>\n<pre><code>$ cat test.sh \n#!\/bin\/bash\ndef=456\necho $def\n$ .\/test.sh \n456\n$ echo $def\n<\/code><\/pre>\n<h4>\u793a\u4f8b3<\/h4>\n<p>\u4f46\u662f\u8fd9\u79cd\u666e\u901a\u53d8\u91cf\u5374\u53ef\u4ee5\u4f20\u9012\u5230subshell\u8fdb\u7a0b\u4e2d, \u4e0d\u8fc7subshell\u4e2d\u5b9a\u4e49\u7684\u666e\u901a\u53d8\u91cf\u5f71\u54cd\u5230\u7236shell.<\/p>\n<pre><code>$ abc=123\n$ (echo $abc)\n123\n$ (abc=789; echo $abc)\n789\n$ echo $abc\n123\n<\/code><\/pre>\n<hr \/>\n<p>\u8fd9\u91cc\u9700\u8981\u6ce8\u610f\u7684\u662f, bash\u8fdb\u7a0b\u4e0eshell\u8fdb\u7a0b\u4e0d\u662f\u4e00\u56de\u4e8b. \u4e24\u8005\u7684\u533a\u522b\u53ef\u4ee5\u901a\u8fc7<code>$$<\/code>\u7279\u6b8a\u53d8\u91cf\u67e5\u770b, \u8fd9\u8868\u793a\u5f53\u524dbash\u8fdb\u7a0b\u7684\u8fdb\u7a0b\u53f7, \u6216\u8005\u4e5f\u53ef\u4ee5\u901a\u8fc7<code>$BASH_SUBSHELL<\/code>\u53d8\u91cf\u67e5\u770b, \u5b83\u8868\u793a\u5b50shell\u7684\u5c42\u7ea7\u6570.<\/p>\n<pre><code>$ echo $$; echo $BASH_SUBSHELL\n3299\n0\n$ (echo $$; echo $BASH_SUBSHELL)\n3299\n1\n<\/code><\/pre>\n<p>\u53ef\u4ee5\u770b\u5230, \u8fd9\u79cd\u901a\u8fc7\u5c0f\u62ec\u53f7\u521b\u5efa\u7684subshell, \u4e0e\u539fshell\u540c\u7528\u540c\u4e00\u4e2abash\u8fdb\u7a0b, \u53ea\u662fshell\u5c42\u7ea7\u4f1a\u589e\u52a0. subshell\u662f\u5141\u8bb8\u5d4c\u5957\u8c03\u7528\u7684\uff0c\u53ef\u4ee5\u5728\u51fd\u6570\u6216\u5706\u62ec\u53f7\u7ed3\u6784\u5185\u518d\u6b21\u8c03\u7528\u5706\u62ec\u53f7\u7ed3\u6784\u521b\u5efasubshell.<\/p>\n<p>\u800c\u6267\u884c\u811a\u672c\u65f6, \u7531\u4e8e\u7b2c\u4e00\u884c<code>#!\/bin\/bash<\/code>\u8fd9\u4e00\u53e5\u7684\u5b58\u5728, shell\u811a\u672c\u90fd\u662f\u65b0\u5efabash\u8fdb\u7a0b\u7136\u540e\u518d\u6267\u884c\u5176\u4e2d\u7684\u547d\u4ee4.<\/p>\n<pre><code>$ cat test.sh\n#!\/bin\/bash\necho $$; echo $BASH_SUBSHELL\n$ .\/test.sh\n5990\n0\n<\/code><\/pre>\n<p>\u8fd9\u4e24\u8005\u7684\u533a\u522b\u5e94\u8be5\u7528\u66f4\u6df1\u5c42\u7684\u6db5\u4e49, \u76ee\u524d\u5148\u4fdd\u7559\u8fd9\u4e2a\u95ee\u9898&lt;???&gt;.<\/p>\n<h3>\u7528\u6237\u53d8\u91cf\u5206\u6790<\/h3>\n<p>\u7528\u6237\u7ea7\u53d8\u91cf\u4e0ebash\u7ea7\u53d8\u91cf\u6700\u5927\u7684\u4e0d\u540c, \u5e94\u8be5\u5c31\u662f\u524d\u8005\u53ef\u4ee5\u5ef6\u7236\u5b50\u5173\u7cfb\u4e0a\u4e0b\u4f20\u9012\u800c\u540e\u8005\u4e0d\u53ef\u4ee5.<\/p>\n<p>\u901a\u8fc72,3,5\u4e2d\u4efb\u610f\u4e00\u79cd\u65b9\u5f0f\u53ef\u4ee5\u521b\u5efa\u7528\u6237\u7ea7\u53d8\u91cf.<\/p>\n<pre><code>$ cat test.sh \n#!\/bin\/bash\necho &#039;begin&#039;\necho $abc\necho &#039;end&#039;\n$ export abc=789\n$ .\/test.sh \nbegin\n789\nend\n<\/code><\/pre>\n<h2>\u4e0d\u540c\u7ea7\u522b\u53d8\u91cf\u64cd\u4f5c<\/h2>\n<h3>1. set\u547d\u4ee4<\/h3>\n<p>set\u547d\u4ee4\u4f5c\u7528\u4e3b\u8981\u662f\u663e\u793a\u7cfb\u7edf\u4e2d\u5df2\u7ecf\u5b58\u5728\u7684shell\u53d8\u91cf, \u6216\u8005\u7528\u4e8e\u66f4\u6539shell\u7279\u6027\uff0c\u7b26\u53f7&quot;+\u201c\u548c\u201d-&quot;\u7684\u4f5c\u7528\u5206\u522b\u662f\u6253\u5f00\u548c\u5173\u95ed\u6307\u5b9a\u7684\u6a21\u5f0f. set\u547d\u4ee4\u672c\u8eab\u4e0d\u80fd\u591f\u5b9a\u4e49\u65b0\u7684shell\u53d8\u91cf.<\/p>\n<p>\u5728\u4e0d\u6dfb\u52a0\u4efb\u4f55\u9009\u9879\u7684\u65f6\u5019, \u663e\u793a\u5f53\u524d\u4f1a\u8bdd\u4e2d\u6240\u6709\u5408\u6cd5\u7684\u53d8\u91cf\uff0c\u5305\u62ec\u7528\u6237\u7ea7\u53d8\u91cf.<\/p>\n<h3>2. env\u547d\u4ee4<\/h3>\n<p>\u4e0d\u63a5\u4efb\u4f55\u53c2\u6570\u7684\u60c5\u51b5\u4e0b, \u663e\u793a\u5f53\u524d\u7684\u7528\u6237\u7ea7\u522b\u53d8\u91cf.<\/p>\n<p><code>env abc=123<\/code>\u53ef\u4ee5\u5c06<code>abc<\/code>\u8bbe\u7f6e\u4e3a\u7528\u6237\u7ea7\u522b\u53d8\u91cf, \u5f53\u524dbash\u8fdb\u7a0b\u53ca\u5176\u5b50\u8fdb\u7a0b\u4e2d\u6709\u6548.<\/p>\n<p><code>env -u abc<\/code>\u53ef\u4ee5\u4ece\u5f53\u524d\u7528\u6237\u7ea7\u73af\u5883\u53d8\u91cf\u4e2d\u5220\u9664\u53d8\u91cf<code>abc<\/code>.<\/p>\n<h3>3. export\u547d\u4ee4<\/h3>\n<p>\u5728\u4e0d\u63a5\u4efb\u4f55\u53c2\u6570\u65f6, \u663e\u793a\u5f53\u524d\u5bfc\u51fa\u6210\u7528\u6237\u53d8\u91cf\u7684bash\u53d8\u91cf, \u8fd9\u4e9b\u53d8\u91cf\u539f\u672c\u662fbash\u7ea7\u522b\u53d8\u91cf, \u4e4b\u540e\u88ab\u63d0\u5347\u81f3\u7528\u6237\u7ea7\u522b.<\/p>\n<p>\u5b83\u53ef\u4ee5\u63a5\u4e00\u4e2a\u53c2\u6570, \u7c7b\u4f3c\u4e8e<code>export abc=123<\/code>\u6216\u662f<code>abc=123 &amp;&amp; export abc<\/code>, \u5c06\u666e\u901a\u53d8\u91cf<code>abc<\/code>\u63d0\u5347\u5230\u7528\u6237\u53d8\u91cf\u7ea7\u522b, \u4e4b\u540e\u901a\u8fc7\u6b64shell\u542f\u52a8\u7684\u547d\u4ee4, \u90fd\u53ef\u4ee5\u8bfb\u53d6\u5230\u8fd9\u4e2a\u53d8\u91cf, \u5b83\u7684\u751f\u547d\u5468\u671f\u4ec5\u9650\u4e8e\u5f53\u524dshell\u7ed3\u675f\u4e4b\u524d.<\/p>\n<p>\u4e0d\u8fc7, <code>export<\/code>\u7684\u8f93\u51fa\u90fd\u5f88\u76f8\u4f3c, \u5982\u4e0b<\/p>\n<pre><code>$ export\ndeclare -x CLASSPATH=&quot;.:\/usr\/local\/jdk1.8.0_101\/lib\/dt.jar:\/usr\/local\/jdk1.8.0_101\/lib\/tools.jar&quot;\ndeclare -x HISTCONTROL=&quot;ignoredups&quot;\ndeclare -x HISTSIZE=&quot;1000&quot;\n...\n<\/code><\/pre>\n<p>\u6240\u6709\u88ab\u63d0\u5347\u81f3\u7528\u6237\u7ea7\u522b\u7684\u53d8\u91cf, \u5b9e\u9645\u4e0a\u90fd\u662f\u901a\u8fc7<code>declare<\/code>\u547d\u4ee4\u4e3abash\u7ea7\u53d8\u91cf\u8d4b\u4e88\u4e86<code>-x<\/code>\u5c5e\u6027, \u6682\u65f6\u4e0d\u77e5\u9053\u8fd9\u4e24\u4e2a\u547d\u4ee4\u4e4b\u95f4\u6709\u4f55\u5185\u5728\u7684\u5173\u8054&lt;???&gt;.<\/p>\n<h3>4. declare\u547d\u4ee4<\/h3>\n<p>\u5728\u4e0d\u63a5\u4efb\u4f55\u53c2\u6570\u65f6, \u53ef\u4ee5\u663e\u793a\u5f53\u524d\u4f1a\u8bdd\u4e2d\u6240\u6709\u5408\u6cd5\u53d8\u91cf\u2026\u8c8c\u4f3c\u4e0eset\u7684\u8f93\u51fa\u76f8\u540c, \u4e0d\u4ec5\u5305\u62ec\u666e\u901a\u53d8\u91cf, \u8fd8\u6709\u7528\u6237\u7ea7\u522b\u53d8\u91cf.<\/p>\n<p>~<code>declare abc=123<\/code>\u53ef\u4ee5\u5c06\u53d8\u91cf<code>abc<\/code>\u58f0\u660e\u4e3a\u4e00\u4e2a\u666e\u901a\u53d8\u91cf.~ \u8fd9\u53e5\u8bdd\u88ab\u6ce8\u91ca\u6389\u4e86, \u4f46\u4e5f\u4e0d\u80fd\u5b8c\u5168\u8bf4\u662f\u9519\u8bef\u7684, \u5728CentOS7\u7cfb\u7edf\u4e2d<code>declare abc=123<\/code>\u9ed8\u8ba4\u4e3a\u9644\u5e26<code>-x<\/code>\u5c5e\u6027, \u5373\u5c06\u5176\u58f0\u660e\u4e3a\u7528\u6237\u7ea7\u522b\u53d8\u91cf, \u6240\u4ee5\u5982\u679c\u4e0d\u5e26\u4efb\u4f55\u5c5e\u6027, <code>abc<\/code>\u4e5f\u672c\u5e94\u8be5\u53ea\u662f\u4e00\u4e2a\u666e\u901a\u53d8\u91cf\u800c\u5df2.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linux\u73af\u5883\u53d8\u91cf\u8be6\u89e3 1. \u751f\u6548\u65f6\u673a \u4e0e\u73af\u5883\u53d8\u91cf\u6709\u5173\u7684\u56db\u4e2a\u6587\u4ef6 \/etc\/profile \/etc\/bashrc ~\/.bash_pr   \u2026 &#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[14],"tags":[],"_links":{"self":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts\/8902"}],"collection":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=8902"}],"version-history":[{"count":1,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/8902\/revisions"}],"predecessor-version":[{"id":8903,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/8902\/revisions\/8903"}],"wp:attachment":[{"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8902"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8902"},{"taxonomy":"post_tag","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8902"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}