bash<\/em>shell \u662f\u53ef\u7528\u4e8e Linux \u7684\u51e0\u4e2a shell \u4e4b\u4e00\uff0c\u4e5f\u88ab\u79f0\u4e3a Bourne-again shell<\/em>\uff0c\u662f\u6839\u636e\u4e00\u4e2a\u65e9\u671f\u7684 shell (\/bin\/sh<\/em>) \u7684\u521b\u5efa\u8005 Stephen Bourne \u6765\u547d\u540d\u7684\u3002Bash \u9ad8\u5ea6\u517c\u5bb9 sh\uff0c\u4f46\u5b83\u5728\u51fd\u6570\u548c\u7f16\u7a0b\u529f\u80fd\u4e0a\u90fd\u63d0\u4f9b\u4e86\u8bb8\u591a\u6539\u8fdb\u3002\u5b83\u5408\u5e76\u4e86\u6765\u81ea Korn shell (ksh) \u548c C shell (csh) \u7684\u7279\u6027\uff0c\u60f3\u8981\u6210\u4e3a\u4e00\u4e2a\u7b26\u5408 POSIX \u7684 shell\u3002<\/p>\n\n\n\n \u5728\u6df1\u5165\u4e86\u89e3 bash \u4e4b\u524d\uff0c\u56de\u60f3\u4e00\u4e0b 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\u76ee\u524d\u4e3a\u6b62\uff0c\u6211\u4eec\u7684\u6240\u6709\u53d8\u91cf\u5f15\u7528\u90fd\u4ee5\u7a7a\u767d\u7ec8\u6b62\uff0c\u6240\u4ee5\u5f88\u6e05\u695a\u53d8\u91cf\u540d\u5728\u4f55\u5904\u7ed3\u675f\u3002\u4e8b\u5b9e\u4e0a\uff0c\u53d8\u91cf\u540d\u4ec5\u80fd\u7531\u5b57\u6bcd\u3001\u6570\u5b57\u6216\u4e0b\u5212\u7ebf\u7ec4\u6210\u3002shell \u77e5\u9053\u53d8\u91cf\u540d\u4f1a\u5728\u627e\u5230\u53e6\u5916\u7684\u5b57\u7b26\u65f6\u7ed3\u675f\u3002\u6709\u65f6\uff0c\u60a8\u9700\u8981\u5728\u542b\u4e49\u6a21\u7cca\u8868\u8fbe\u5f0f\u4e2d\u4f7f\u7528\u53d8\u91cf\u3002\u5728\u8fd9\u4e9b\u60c5\u51b5\u4e0b\uff0c\u53ef\u4ee5\u4f7f\u7528\u82b1\u62ec\u53f7\u6765\u8868\u793a\u53d8\u91cf\u540d\uff0c\u5982 \u6e05\u5355\u4e2d\u6240\u793a\u3002<\/p>\n\n\n\n \u5c06\u82b1\u62ec\u53f7\u7528\u4e8e\u53d8\u91cf\u540d \u6ca1\u6709\u4efb\u4f55\u9009\u9879\u6216\u53c2\u6570\u7684 \u6e05\u5355 11\u663e\u793a\u4e86\u6ca1\u6709\u4efb\u4f55\u53c2\u6570\u7684 \u5907\u6ce8\uff1a<\/strong>\u5982\u679c\u60a8\u7684\u7cfb\u7edf\u672a\u5b89\u88c5 ksh (Korn) \u6216 tcsh shell\uff0c\u60a8\u9700\u8981\u5b89\u88c5\u5b83\u4eec\u6765\u81ea\u884c\u6267\u884c\u8fd9\u4e9b\u7ec3\u4e60\u3002 [ian@atticf20 ~]$ env \u5f53 bash \u8bbe\u7f6e SHELL \u53d8\u91cf\u65f6\uff0c\u4f1a\u5c06\u5176\u5bfc\u51fa\u81f3\u73af\u5883\u4e2d\u3002\u65b0 bash shell \u5df2\u5728\u73af\u5883\u4e2d\u521b\u5efa\u4e86 3 \u4e2a\u5176\u4ed6\u53d8\u91cf\u3002\u5728 ksh \u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u6709 5 \u4e2a\u73af\u5883\u53d8\u91cf\uff0c\u4f46\u6211\u4eec\u5c1d\u8bd5\u56de\u9001 SHELL \u53d8\u91cf\u503c\u65f6\uff0c\u83b7\u5f97\u4e86\u8f93\u51fa \/bin\/sh\u3002\u4e00\u4e9b\u66f4\u65e9\u7684 ksh \u7248\u672c\u4ec5\u63d0\u4f9b\u4e00\u4e2a\u7a7a\u767d\u884c\u6765\u8868\u660e SHELL \u53d8\u91cf\u672a\u8bbe\u7f6e\u3002\u6700\u540e\uff0ctcsh \u672a\u521b\u5efa\u4efb\u4f55\u73af\u5883\u53d8\u91cf\uff0c\u5e76\u5728\u6211\u4eec\u5c1d\u8bd5\u5f15\u7528 SHELL \u7684\u503c\u65f6\u751f\u6210\u4e86\u4e00\u4e2a\u9519\u8bef\u3002<\/p>\n\n\n\n \u6e05\u5355 11\u663e\u793a\u4e86 shell \u5904\u7406\u53d8\u91cf\u548c\u73af\u5883\u7684\u4e0d\u540c\u884c\u4e3a\u3002\u5c3d\u7ba1\u672c\u6559\u7a0b\u91cd\u70b9\u4ecb\u7ecd\u7684\u662f bash\uff0c\u4f46\u4e5f\u6709\u5fc5\u8981\u77e5\u9053\u4e0d\u662f\u6240\u6709 shell \u90fd\u5177\u6709\u76f8\u540c\u7684\u884c\u4e3a\u3002\u6b64\u5916\uff0cshell \u5c06\u6839\u636e\u5b83\u662f\u5426\u662f \u767b\u5f55 shell<\/em>\u6765\u91c7\u53d6\u4e0d\u540c\u884c\u4e3a\u3002\u5c31\u76ee\u524d\u800c\u8a00\uff0c\u6211\u4eec\u4ec5\u5047\u8bbe\u767b\u5f55 shell \u662f\u60a8\u767b\u5f55\u5230\u7cfb\u7edf\u65f6\u83b7\u5f97\u7684 shell\uff1b\u5982\u679c\u613f\u610f\uff0c\u60a8\u8fd8\u53ef\u4ee5\u542f\u52a8\u5176\u4ed6 shell \u6765\u5145\u5f53\u767b\u5f55 shell\u3002\u4e0a\u9762\u4f7f\u7528 \u8ba9\u6211\u4eec\u5c1d\u8bd5\u5728\u8fd9\u4e9b\u975e\u767b\u5f55 shell \u4e2d\u663e\u793a SHELL \u53d8\u91cf\u7684\u503c\uff1a<\/p>\n\n\n\n \u53ef\u4ee5\u4f7f\u7528 [ian@atticf20 ~]$ echo $- [ian@atticf20 ~]$ set -u;echo $- himBH<\/p>\n\n\n\n \u5982\u679c\u4f7f\u7528\u6ca1\u6709\u4efb\u4f55\u9009\u9879\u7684 \u6700\u540e\u4e00\u4e2a\u8981\u4ecb\u7ecd\u7684\u547d\u4ee4\u662f \u4f7f\u7528 exec bash shell bashshell \u662f\u53ef\u7528\u4e8e Linux \u7684\u51e0\u4e2a shell \u4e4b\u4e00\uff0c\u4e5f\u88ab\u79f0\u4e3a Bourn […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[183,405],"class_list":["post-2041","post","type-post","status-publish","format-standard","hentry","category-operating-system","tag-linux-2","tag-405"],"_links":{"self":[{"href":"https:\/\/www.wxcn.com\/index.php?rest_route=\/wp\/v2\/posts\/2041","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wxcn.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wxcn.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wxcn.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wxcn.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2041"}],"version-history":[{"count":0,"href":"https:\/\/www.wxcn.com\/index.php?rest_route=\/wp\/v2\/posts\/2041\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.wxcn.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2041"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wxcn.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2041"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wxcn.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2041"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}cd<\/code>\u3001break<\/code>\u548c exec<\/code>\u3002\u5176\u4ed6\u547d\u4ee4\u662f \u5916\u90e8<\/em>\u547d\u4ee4\u3002<\/p>\n\n\n\n\u6e05\u5355 1. \u4e00\u4e9b\u5178\u578b\u7684\u7528\u6237\u63d0\u793a\u7b26
<\/h5>\n\n\n\n[ian@atticf20 ~]$ <\/code>jenni@atticf20:data <\/code>$<\/code><\/p>\n\n\n\n\u6e05\u5355 2. \u8d85\u7ea7\u7528\u6237\u6216\u6839\u7528\u6237\u63d0\u793a\u7b26\u793a\u4f8b
<\/h5>\n\n\n\n[root@atticf20 ~]# <\/code>atticf20:~#<\/code><\/p>\n\n\n\nsudo<\/code>\u547d\u4ee4\u6267\u884c\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u60a8\u7684\u63d0\u793a\u7b26\u4e0d\u4f1a\u53d1\u751f\u66f4\u6539\uff0c\u4f46\u60a8\u5e94\u8be5\u77e5\u9053\u9700\u8981\u4f7f\u7528 sudo<\/code>\u6267\u884c\u666e\u901a\u7528\u6237\u65e0\u6743\u6267\u884c\u7684\u547d\u4ee4\u3002<\/p>\n\n\n\n\u73af\u5883\u53d8\u91cf<\/h2>\n\n\n\n
\u4e00\u4e9b\u5e38\u89c1\u7684 bash \u73af\u5883\u53d8\u91cf<\/h5>\n\n\n\n
\u540d\u79f0<\/th> \u529f\u80fd<\/th><\/tr><\/thead> USER<\/td> \u767b\u5f55\u7528\u6237\u7684\u540d\u79f0<\/td><\/tr> UID<\/td> \u767b\u5f55\u7528\u6237\u7684\u7528\u6237 id \u6570\u5b57<\/td><\/tr> HOME<\/td> \u7528\u6237\u7684\u4e3b\u76ee\u5f55<\/td><\/tr> PWD<\/td> \u5f53\u524d\u5de5\u4f5c\u76ee\u5f55<\/td><\/tr> SHELL<\/td> shell \u7684\u540d\u79f0<\/td><\/tr> $<\/td> \u8fd0\u884c\u7684 bash shell\uff08\u6216\u5176\u4ed6\uff09\u8fdb\u7a0b\u7684\u8fdb\u7a0b id\uff08\u6216 PID<\/em>\uff09<\/td><\/tr> PPID<\/td> \u542f\u52a8\u6b64\u8fdb\u7a0b\u7684\u8fdb\u7a0b\u7684\u8fdb\u7a0b id\uff08\u4e5f\u5c31\u662f\u7236\u8fdb\u7a0b\u7684 id\uff09<\/td><\/tr> ?<\/td> \u4e0a\u4e00\u4e2a\u547d\u4ee4\u7684\u9000\u51fa\u4ee3\u7801<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n \u73af\u5883\u53d8\u91cf\u548c shell \u53d8\u91cf
[ian@atticf20 ~]$ echo $USER $UID<\/code>ian 1000<\/code>[ian@atticf20 ~]$ echo $SHELL $HOME $PWD<\/code>\/bin\/bash \/home\/ian \/home\/ian<\/code>[ian@atticf20 ~]$ (exit 0);echo $?;(exit 4);echo $?<\/code>
0
4[ian@atticf20 ~]$ echo $$ $PPID<\/code>3175 2457<\/code><\/h5>\n\n\n\nexport<\/code>\u547d\u4ee4\u5bfc\u51fa\u53d8\u91cf\u540d\u3002\u4f5c\u4e3a bash \u4e2d\u7684\u5feb\u6377\u65b9\u5f0f\uff0c\u53ef\u4ee5\u5728\u4e00\u4e2a\u6b65\u9aa4\u4e2d\u5206\u914d\u4e00\u4e2a\u503c\u5e76\u5bfc\u51fa\u53d8\u91cf\u3002<\/p>\n\n\n\nps<\/code>\u547d\u4ee4\u663e\u793a\u6b63\u5728\u8fd0\u884c\u7684\u547d\u4ee4\u7684\u4fe1\u606f\u3002<\/p>\n\n\n\n[ian@atticf20 ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>3175\u00a0 2457 bash <\/code>[ian@atticf20 ~]$ bash<\/code>[ian@atticf20 ~]$\u00a0 ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>4325\u00a0 3175 bash <\/code>[ian@atticf20 ~]$ VAR1=var1<\/code>[ian@atticf20 ~]$ VAR2=var2<\/code>[ian@atticf20 ~]$ export VAR2<\/code>[ian@atticf20 ~]$ export VAR3=var3<\/code>[ian@atticf20 ~]$ echo $VAR1 $VAR2 $VAR3<\/code>var1 var2 var3 <\/code>[ian@atticf20 ~]$ echo $VAR1 $VAR2 $VAR3 $SHELL<\/code>var1 var2 var3 \/bin\/bash <\/code>[ian@atticf20 ~]$ ksh$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>4427\u00a0 4325 ksh <\/code>$ export VAR4=var4<\/code>$ echo $VAR1 $VAR2 $VAR3 $VAR4 $SHELL<\/code>var2 var3 var4 \/bin\/bash <\/code>$ exit[ian@atticf20 ~]$ echo $<\/code>VAR1 $VAR2 $VAR3 $VAR4 $SHELLvar1 var2 var3 \/bin\/bash <\/code>[ian@atticf20 ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>4325\u00a0 3175 bash <\/code>[ian@atticf20 ~]$ exit<\/code>exit <\/code>[ian@atticf20 ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>3175\u00a0 2457 bash <\/code>[ian@atticf20 ~]$ echo $VAR1 $VAR2 $VAR3 $VAR4 $SHELL<\/code>\/bin\/bash <\/code>[ian@echidna ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>2559\u00a0 2558 -bash <\/code>[ian@echidna ~]$ bash<\/code>[ian@echidna ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>2811\u00a0 2559 bash <\/code>[ian@echidna ~]$ VAR1=var1<\/code>[ian@echidna ~]$ VAR2=var2<\/code>[ian@echidna ~]$ export VAR2<\/code>[ian@echidna ~]$ export VAR3=var3<\/code>[ian@echidna ~]$ echo $VAR1 $VAR2 $VAR3<\/code>var1 var2 var3 <\/code>[ian@echidna ~]$ echo $VAR1 $VAR2 $VAR3 $SHELL<\/code>var1 var2 var3 \/bin\/bash <\/code>[ian@echidna ~]$ ksh$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>2840\u00a0 2811 ksh <\/code>$ export VAR4=var4$ echo $VAR1 $VAR2 $VAR3 $VAR4 $SHELL<\/code>var2 var3 var4 \/bin\/bash <\/code>$ exit<\/code>[ian@echidna ~]$ echo $VAR1 $VAR2 $VAR3 $VAR4 $SHELL<\/code>var1 var2 var3 \/bin\/bash <\/code>[ian@echidna ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>2811\u00a0 2559 bash <\/code>[ian@echidna ~]$ exit<\/code>exit <\/code>[ian@echidna ~]$ ps -p $$ -o \"pid ppid cmd\"<\/code>PID\u00a0 PPID CMD <\/code>2559\u00a0 2558 -bash <\/code>[ian@echidna ~]$ echo $VAR1 $VAR2 $VAR3 $VAR4 $SHELL<\/code>\/bin\/bash<\/code><\/p>\n\n\n\necho<\/code>\u547d\u4ee4\u4ec5\u663e\u793a\u4e86 VAR2\u3001VAR3 \u548c VAR4 \u7684\u503c\uff0c\u53ef\u4ee5\u786e\u8ba4 VAR1 \u672a\u5bfc\u51fa\u3002\u60a8\u770b\u5230 SHELL \u53d8\u91cf\u7684\u503c\u672a\u53d1\u751f\u6539\u53d8\u662f\u5426\u611f\u5230\u5f88\u5947\u602a\uff0c\u56e0\u4e3a\u63d0\u793a\u7b26\u5df2\u53d1\u751f\u6539\u53d8\uff1f\u60a8\u4e0d\u80fd\u59cb\u7ec8\u4f9d\u9760 SHELL \u6765\u544a\u8bc9\u60a8\u5728\u54ea\u4e9b shell \u4e0b\u8fd0\u884c\uff0c\u4f46 ps<\/code>\u547d\u4ee4\u4f1a\u544a\u8bc9\u60a8\u5b9e\u9645\u547d\u4ee4\u3002\u8bf7\u6ce8\u610f\uff0cps<\/code>\u5728\u7b2c\u4e00\u4e2a bash shell \u524d\u9762\u653e\u5165\u4e86\u4e00\u4e2a\u8fde\u5b57\u7b26 (-)\uff0c\u8868\u660e\u8fd9\u662f\u4e00\u4e2a \u767b\u5f55 shell<\/em>\u3002<\/li>-c<\/code>\u9009\u9879\uff0c\u60a8\u53ef\u4ee5\u5c06\u4e00\u4e2a\u547d\u4ee4\u4f20\u9012\u7ed9\u5176\u4ed6 shell\uff0c\u8be5 shell \u5c06\u6267\u884c\u8be5\u547d\u4ee4\u5e76\u8fd4\u56de\u3002\u5982\u679c\u4f20\u9012\u4e00\u4e2a\u5e26\u5f15\u53f7\u7684\u5b57\u7b26\u4e32\u4f5c\u4e3a\u547d\u4ee4\uff0c\u5916\u90e8 shell \u5c06\u6d88\u9664\u5f15\u53f7\u5e76\u4f20\u9012\u5b57\u7b26\u4e32\u3002\u5982\u679c\u4f7f\u7528\u53cc\u5f15\u53f7\uff0c\u53d8\u91cf\u6269\u5c55\u4f1a\u5728\u4f20\u9012\u5b57\u7b26\u4e32 \u4e4b\u524d<\/strong>\u6267\u884c\uff0c\u6240\u4ee5\u7ed3\u679c\u53ef\u80fd\u4e0d\u7b26\u5408\u9884\u671f\u3002\u8be5 shell \u548c\u547d\u4ee4\u5c06\u5728\u53e6\u4e00\u4e2a\u8fdb\u7a0b\u4e2d\u8fd0\u884c\uff0c\u6240\u4ee5\u5b83\u4eec\u5c06\u62e5\u6709\u53e6\u4e00\u4e2a PID\u3002\u6e05\u5355 9\u6f14\u793a\u4e86\u8fd9\u4e9b\u6982\u5ff5\u3002\u9876\u7ea7 bash shell \u7684 PID \u5df2\u7a81\u51fa\u663e\u793a\u3002<\/p>\n\n\n\n
[ian@atticf20 ~]$ echo “$SHELL” ‘$SHELL’ “$$” ‘$$’
\/bin\/bash $SHELL 3175$$
[ian@atticf20 ~]$ bash -c “echo Expand in parent $$ $PPID”
Expand in parent 31752457
[ian@atticf20 ~]$ bash -c ‘echo Expand in child $$ $PPID’
Expand in child 4541 3175<\/p>\n\n\n\n
[ian@atticf20 ~]$ echo “-$HOME\/abc-“
-\/home\/ian\/abc-
[ian@atticf20 ~]$ echo “-$HOME_abc-“
[ian@atticf20 ~]$ echo “-${HOME}_abc-“
-\/home\/ian_abc-<\/p>\n\n\n\nEnv<\/h3>\n\n\n\n
env<\/code>\u547d\u4ee4\u663e\u793a\u5f53\u524d\u73af\u5883\u53d8\u91cf\u3002\u4e5f\u53ef\u4ee5\u4f7f\u7528\u5b83\u5728\u81ea\u5b9a\u4e49\u73af\u5883\u4e2d\u6267\u884c\u547d\u4ee4\u3002-i<\/code>\uff08\u6216\u8005\u53ea\u662f -<\/code>\uff09\u9009\u9879\u5728\u8fd0\u884c\u547d\u4ee4\u524d\u6e05\u9664\u5f53\u524d\u73af\u5883\uff0c\u800c -u<\/code>\u9009\u9879\u53d6\u6d88\u8bbe\u7f6e\u60a8\u4e0d\u5e0c\u671b\u4f20\u9012\u7684\u73af\u5883\u53d8\u91cf\u3002<\/p>\n\n\n\nenv<\/code>\u547d\u4ee4\u7684\u90e8\u5206\u8f93\u51fa\uff0c\u7136\u540e\u7ed9\u51fa\u4e86 3 \u4e2a\u8c03\u7528\u6ca1\u6709\u7236\u73af\u5883\u7684\u4e0d\u540c shell \u7684\u793a\u4f8b\u3002\u5728\u6211\u4eec\u8ba8\u8bba\u5b83\u4eec\u4e4b\u524d\u8bf7\u4ed4\u7ec6\u770b\u770b\u5b83\u4eec\u3002<\/p>\n\n\n\n
env \u547d\u4ee4
<\/p>\n\n\n\n
XDG_VTNR=2
XDG_SESSION_ID=1
HOSTNAME=atticf20
GPG_AGENT_INFO=\/run\/user\/1000\/keyring\/gpg:0:1
SHELL=\/bin\/bash
TERM=xterm-256color
XDG_MENU_PREFIX=gnome-
VTE_VERSION=4002
HISTSIZE=1000
GJS_DEBUG_OUTPUT=stderr
WINDOWID=35651982
GJS_DEBUG_TOPICS=JS ERROR;JS LOG
QT_GRAPHICSSYSTEM_CHECKED=1
USER=ian
\u2026=\/usr\/bin\/env OLDPWD=\/home\/ian\/Documents [ian@atticf20 ~]$ env -i bash -c ‘echo $SHELL; env’ \/bin\/bash PWD=\/home\/ian SHLVL=1 <\/em>=\/usr\/bin\/env
[ian@atticf20 ~]$ env -i ksh -c ‘echo $SHELL; env’
\/bin\/sh
_=3175<\/em>\/usr\/bin\/env
PWD=\/home\/ian
SHLVL=1
_AST_FEATURES=UNIVERSE – ucb
A__z=”*SHLVL
[ian@atticf20 ~]$ env -i tcsh -c ‘echo $SHELL; env’
SHELL: Undefined variable.<\/p>\n\n\n\n\u53d6\u6d88\u8bbe\u7f6e\u548c\u8bbe\u7f6e<\/h3>\n\n\n\n
env -i<\/code>\u542f\u52a8\u7684 3 \u4e2a shell \u90fd\u4e0d\u662f\u767b\u5f55 shell\u3002\u5c1d\u8bd5\u5c06 -l<\/code>\u9009\u9879\u4f20\u9012\u7ed9 shell \u547d\u4ee4\u672c\u8eab\uff0c\u770b\u770b\u60a8\u4f7f\u7528\u767b\u5f55 shell \u4f1a\u83b7\u5f97\u54ea\u4e9b\u533a\u522b\u3002<\/p>\n\n\n\nunset<\/code>\u547d\u4ee4\u53d6\u6d88\u8bbe\u7f6e\u53d8\u91cf\uff0c\u5e76\u4ece shell \u53d8\u91cf\u5217\u8868\u4e2d\u5220\u9664\u5b83\u3002\u5982\u679c\u53d8\u91cf\u5df2\u5bfc\u51fa\u5230\u73af\u5883\u4e2d\uff0c\u6b64\u547d\u4ee4\u8fd8\u4f1a\u4ece\u73af\u5883\u4e2d\u5220\u9664\u5b83\u3002\u53ef\u4ee5\u4f7f\u7528 set<\/code>\u547d\u4ee4\u63a7\u5236 bash\uff08\u6216\u5176\u4ed6 shell\uff09\u7684\u5de5\u4f5c\u65b9\u5f0f\u7684\u8bb8\u591a\u65b9\u9762\u3002Set \u662f\u4e00\u4e2a shell \u5185\u7f6e\u547d\u4ee4\uff0c\u6240\u4ee5\u5404\u79cd\u9009\u9879\u90fd\u662f\u7279\u5b9a\u4e8e shell \u7684\u3002\u5728 bash \u4e2d\uff0c-u<\/code>\u9009\u9879\u5bfc\u81f4 bash \u62a5\u544a\u53d8\u91cf\u672a\u5b9a\u4e49\u7684\u9519\u8bef\uff0c\u800c\u4e0d\u662f\u5c06\u5b83\u4eec\u89c6\u4e3a\u5df2\u5b9a\u4e49\u4f46\u662f\u7a7a\u7684\u3002\u53ef\u4ee5\u4f7f\u7528 -<\/code>\u6253\u5f00 set<\/code>\u7684\u5404\u79cd\u9009\u9879\uff0c\u4f7f\u7528 +<\/code>\u5173\u95ed\u5b83\u4eec\u3002\u53ef\u4ee5\u4f7f\u7528 echo $-<\/code>\u663e\u793a\u5f53\u524d\u8bbe\u7f6e\u7684\u9009\u9879\u3002<\/p>\n\n\n\n
himBH
[ian@atticf20 ~]$ echo $VAR1<\/p>\n\n\n\n
himuBH
[ian@atticf20 ~]$ echo $VAR1
bash: VAR1: unbound variable
[ian@atticf20 ~]$ VAR1=v1;echo $VAR1
v1
[ian@atticf20 ~]$ unset VAR1;echo $VAR1
bash: VAR1: unbound variable
[ian@atticf20 ~]$ set +u;echo $VAR1;echo $-<\/p>\n\n\n\nset<\/code>\u547d\u4ee4\uff0c\u5b83\u4f1a\u663e\u793a\u6240\u6709 shell \u53d8\u91cf\u548c\u5b83\u4eec\u7684\u503c\uff08\u5982\u679c\u6709\uff09\u3002\u8fd8\u6709\u53e6\u4e00\u4e2a declare<\/code>\u547d\u4ee4\uff0c\u53ef\u7528\u4e8e\u521b\u5efa\u3001\u5bfc\u51fa\u548c\u663e\u793a shell \u53d8\u91cf\u7684\u503c\u3002\u53ef\u4ee5\u4f7f\u7528\u624b\u518c\u9875\u4e86\u89e3\u8bb8\u591a\u5269\u4f59\u7684 set<\/code>\u9009\u9879\u548c declare<\/code>\u547d\u4ee4\u3002\u672c\u6559\u7a0b\u540e\u9762\u90e8\u5206\u5c06\u8ba8\u8bba \u624b\u518c\u9875<\/a>\u3002<\/p>\n\n\n\nExec<\/h3>\n\n\n\n
exec<\/code>\u3002\u53ef\u4f7f\u7528 exec<\/code>\u547d\u4ee4\u8fd0\u884c\u53e6\u4e00\u4e2a\u7a0b\u5e8f\u6765 \u53d6\u4ee3<\/strong>\u5f53\u524d shell\u3002\u6e05\u5355 13\u542f\u52a8\u4e86\u4e00\u4e2a\u5b50 bash shell\uff0c\u7136\u540e\u4f7f\u7528 exec<\/code>\u5c06\u5b83\u66ff\u6362\u4e3a\u4e00\u4e2a Korn shell\u3002\u4ece Korn shell \u9000\u51fa\u65f6\uff0c\u4f1a\u8fd4\u56de\u5230\u539f\u59cb bash shell\uff08\u5728\u672c\u4f8b\u4e2d\u4e3a PID 2852\uff09\u3002<\/p>\n\n\n\n
[ian@atticf20 ~]$ echo $$
3175
[ian@atticf20 ~]$ bash
[ian@atticf20 ~]$ echo $$
4994
[ian@atticf20 ~]$ exec ksh
$ echo $$
4994
$ exit
[ian@atticf20 ~]$ echo $$
3175<\/p>\n","protected":false},"excerpt":{"rendered":"