\u65e0\u8bba\u591a\u590d\u6742\u7684\u811a\u672c\uff0c\u90fd\u662f\u7531\u4e00\u4e9b\u57fa\u672c\u7684\u7ed3\u6784\u6784\u6210\u7684\u3002<\/p>\n
\u4e0b\u9762\uff0c\u4ecb\u7ecd\u4e00\u4e0b\u57fa\u672c\u7684shell\u811a\u672c\u8bed\u6cd5\uff0c\u5feb\u901f\u6d4f\u89c8\uff0c\u6765\u79d2\u719f\u6089\u57fa\u672c\u7684\u811a\u672c\u7f16\u7a0b\u7ed3\u6784\u3002<\/p>\n
# [ ! -e \/vat\/tmp\/a.txt ] && touch \/vat\/tmp\/a.txt\r\n# [ -e \/vat\/tmp\/a.txt ] || touch \/vat\/tmp\/a.txt\r\n<\/code><\/pre>\n\u7279\u70b9\uff1a\u5173\u952e\u8bcd\u5c11\uff0c\u5728\u4e00\u884c\u4e2d\u5373\u53ef\u5b8c\u6210\uff0c\u903b\u8f91\u5206\u660e\uff0c\u53ef\u4ee5\u590d\u5408\u4f7f\u7528\uff0c&&\u548c||\u81ea\u5de6\u5230\u53f3\u5206\u522b\u5224\u65ad\u6765\u5b8c\u6210\u903b\u8f91\u3002<\/p>\n
2\u3001\u5355\u5206\u652fif\u8bed\u53e5<\/h4>\n#!\/bin\/bash\r\n#\r\nif [ $# -lt 1 ]; then\r\n echo \"An argument is needed. Exit\"\r\n exit 4\r\nfi<\/code><\/pre>\n\u7279\u70b9\uff1a\u901a\u5e38\u662f\u4e00\u4e2a\u5f00\u5173\uff0c\u6ee1\u8db3\u6761\u4ef6\u7684\u65f6\u5019\uff0c\u53ef\u4ee5\u7ed3\u675f\u811a\u672c\uff0c\u987a\u5229\u901a\u8fc7\u5224\u65ad\u624d\u80fd\u8fdb\u884c\u5230\u4e0b\u4e00\u6b65\uff1b\u6216\u8005\u5728\u67d0\u4e9b\u7279\u5b9a\u7684\u6761\u4ef6\u7684\u65f6\u5019\u624d\u6267\u884c\u7684\u8bed\u53e5\uff0c\u7528\u4e8e\u7279\u5b9a\u7684\u64cd\u4f5c\u7b49\u3002<\/p>\n
3\u3001\u53cc\u5206\u652f\u7684if\u8bed\u53e5<\/h4>\n#!\/bin\/bash\r\n#\r\nif [ $1 == '--help' ]; then\r\n echo \"Usage: `basename $0` --help\"\r\nelse\r\n echo \"Wrong options...\"\r\nfi<\/code><\/pre>\n\u7279\u70b9\uff1a\u7528\u4e8e\u4e24\u79cd\u60c5\u51b5\u7684\u5224\u65ad\uff0c\u66f4\u591a\u7684\u6761\u4ef6\u5c31\u4e0d\u652f\u6301\u4e86\u3002<\/p>\n
4. \u591a\u5206\u652f\u7684if\u8bed\u53e5<\/h4>\n#!\/bin\/bash\r\n# Usage:\r\n# Author: Liemer_Lius\r\nif [ $1 == '--del' ]; then\r\n echo \"Delleting...\"\r\nelif [ $1 == \"--add\" ]; then\r\n echo \"Adding...\"\r\nelif [ $1 == \"--help\" ]; then\r\n echo \"Usage: ...\"\r\nelse\r\n echo \"Wrong options...\"\r\nfi\r\n\r\n[root@rs1 ~]# .\/i.sh --add\r\nAdding...\r\n[root@rs1 ~]# .\/i.sh --del\r\nDelleting...\r\n[root@rs1 ~]# .\/i.sh --help\r\nUsage: ...\r\n[root@rs1 ~]# .\/i.sh --helppp\r\nWrong options...\r\n<\/code><\/pre>\n\u7279\u70b9\uff1a\u53ef\u4ee5\u5904\u7406\u6bd4\u8f83\u590d\u6742\u7684\u6761\u4ef6\uff0c\u4f46case\u663e\u7136\u66f4\u9002\u5408\u8fd9\u6837\u7684\u573a\u666f\u3002<\/p>\n
5\u3001case\u5224\u65ad<\/h4>\n#!\/bin\/bash\r\n# Usage:\r\n# Author: Liemer_Lius\r\ncase $1 in\r\n[0-9])\r\n echo \"Digit.\";;\r\n[[:alpha:]])\r\n echo \"alpha\";;\r\n*)\r\n echo \"punct...\"\r\nesac\r\n<\/code><\/pre>\n\u7279\u70b9\uff1acase\u4e13\u95e8\u4f9b\u9009\u9879\u591a\u7684\u811a\u672c\u8fdb\u884c\u53c2\u6570\u7684\u5224\u65ad\uff0c\u6709\u4e86\u5b83\uff0c\u591a\u53c2\u6570\u53ef\u4ee5\u8f7b\u677e\u7f16\u8f91\u8fdb\u5165\u811a\u672c\u7684\u63a7\u5236\u6761\u4ef6\uff0c\u5b9e\u73b0\u5feb\u901f\u5b9a\u4f4d\u548c\u6267\u884c\u76f8\u5e94\u547d\u4ee4\u3002<\/p>\n
case\u7684\u6bcf\u4e2a\u8bed\u53e5\u4e2d\uff0c\u53ea\u6709\u6700\u540e\u4e00\u4e2a\u8bed\u53e5\u53ef\u4ee5\u4e0d\u52a0\u53cc\u5f15\u53f7\uff0c\u53cc\u5f15\u53f7\u53ef\u4ee5\u6362\u884c\u52a0\uff0c\u66f4\u52a0\u7f8e\u89c2\u3002<\/p>\n
6. do\u5faa\u73af<\/h4>\n#!\/bin\/bash\r\n# Usage:\r\n# Author: Liemer_Lius\r\nfor i in {1..10}; do\r\n echo -n \"$i,\"\r\ndone\r\necho\r\nfor j in $(seq 2 2 24); do\r\n echo -n \"$j,\"\r\ndone\r\necho\r\nfor k in {hello,world,i,am,who,i,am}; do\r\n echo -n \"$k,\"\r\ndone\r\necho\r\n[root@rs1 ~]# .\/j.sh \r\n1,2,3,4,5,6,7,8,9,10,\r\n2,4,6,8,10,12,14,16,18,20,22,24,\r\nhello,world,i,am,who,i,am,\r\n<\/code><\/pre>\n\u7279\u70b9\uff1a\u7528\u4e8e\u6709\u9650\u6b21\u6570\u7684\u5faa\u73af\uff0c\u901a\u5e38\u7528{1..9}(\u8868\u793a1-9)\uff0c$(seq 10)(seq\u7684\u547d\u4ee4\u7ed3\u679c\u5f15\u7528)\u6765\u5b9e\u73b0\u6b21\u6570\u7684\u9650\u5236\uff0c\u4e5f\u53ef\u4ee5\u7528\u4e00\u4e2a{a,b,c,d}\u8fd9\u79cd\u7c7b\u578b\u7684\u5217\u8868\u6765\u505a\u4e3a\u9009\u62e9\uff08\u7528\u4e8e\u9009\u9879\u5c11\u7684\u60c5\u51b5\uff09\u3002<\/p>\n
7\u3001while\u5faa\u73af<\/h4>\n# \u4e00\u822c\u7528\u6cd5\r\n#!\/bin\/bash\r\n# Usage:\r\n# Author: Liemer_Lius\r\ndeclare -i I=0\r\nwhile [ $I -le 10 ]; do\r\n echo -n \"$I,\"\r\n let I+=1\r\ndone\r\necho\r\n\r\n[root@rs1 ~]# .\/k.sh \/\/ \u6267\u884c\u811a\u672c\r\n0,1,2,3,4,5,6,7,8,9,10,\r\n\r\n# \u5e38\u7528\u5173\u952e\u8bcd\uff1acontinue\uff0cbreak\r\n#!\/bin\/bash\r\n# Usage:\r\n# Author: Liemer_Lius\r\ndeclare -i I=0\r\nwhile [ $I -le 10 ]; do\r\n if [ $I -eq 3 ]; then\r\n let I=$[$I+1]\r\n continue\r\n elif [ $I -eq 9 ]; then\r\n break\r\n else\r\n echo -n \"$I,\"\r\n fi\r\n let I=$[$I+1]\r\ndone\r\necho 'Finished'\r\n\r\n[root@rs1 ~]# .\/l.sh \/\/ \u6267\u884c\u811a\u672c\r\n0,1,2,4,5,6,7,8,Finished\r\n\r\n# \u4e0eread\u7684\u8054\u7528\r\n#!\/bin\/bash\r\n# Usage:\r\n# Author: Liemer_Lius\r\ncut -d: -f1 \/etc\/passwd |head > a.txt\r\nwhile read USER; do\r\n echo \"Hello, $USER...\"\r\ndone < a.txt\r\n\r\n[root@rs1 ~]# .\/q.sh \/\/ \u6267\u884c\u7ed3\u679c\r\nHello, root...\r\nHello, bin...\r\nHello, daemon...\r\nHello, adm...\r\nHello, lp...\r\nHello, sync...\r\nHello, shutdown...\r\nHello, halt...\r\nHello, mail...\r\nHello, uucp...\r\n<\/code><\/pre>\n\u7279\u70b9\uff1awhile\u5faa\u73af\u5f88\u5bb9\u6613\u4ea7\u751f\u6b7b\u5faa\u73af\uff0c\u8fd9\u65f6\u5019bash -x\u4e5f\u4e0d\u597d\u770b\u5230\u5faa\u73af\u7684\u9519\u8bef\uff0c\u56e0\u4e3a\u6839\u672c\u505c\u4e0d\u4e0b\u6765\u3002\u6240\u4ee5\uff0cwhile\u5faa\u73af\u7684\u5f00\u5173\u5c24\u4e3a\u91cd\u8981\u3002<\/p>\n
continue\u5173\u952e\u8bcd\u662f\u8df3\u8fc7\u672c\u6b21\u5faa\u73af\uff0c\u8fdb\u5165\u4e0b\u4e00\u4e2a\u5faa\u73af\uff1b<\/p>\n
break\u662f\u5f7b\u5e95\u9000\u51fa\u5faa\u73af\uff0c\u4f46\u662f\u8fd8\u6267\u884c\u5faa\u73af\u4e4b\u5916\u7684\u8bed\u53e5\uff1b<\/p>\n
exit\u662f\u9000\u51fa\u811a\u672c\u3002<\/p>\n
\u4e0a\u9762\u811a\u672c\u4e2d\uff0c$I=3\u7684\u65f6\u5019\uff0c\u5355\u72ec\u5bf9$I\u505a\u4e86\u4e00\u4e2a\u8d4b\u503c\uff0c\u5982\u679c\u6ca1\u6709\u8fd9\u4e2a\u8d4b\u503c\uff0ccontinue\u8df3\u51fa\u672c\u6b65\u5faa\u73af\u540e\uff0cI\u4f1a\u4e00\u76f4\u7b49\u4e8e3\uff0c\u8fdb\u5165\u6b7b\u5faa\u73af\uff1b<\/p>\n
# wihle\u5faa\u73af\u4e00\u76f4\u4e3a\u771f\u7684\u5224\u65ad\u6761\u4ef6\u5217\u4e3e\uff1a\r\n\r\nwhile :; do \/\/ \u5f88\u591a\u65f6\u5019\uff0c\u7528\u5192\u53f7\u6765\u8868\u793aTrue\u7684\u65f6\u5019\r\n echo \"Hello...\"\r\n sleep 1\r\ndone\r\n[root@rs1 ~]# .\/m.sh \r\nHello...\r\nHello...\r\n^C\r\n\r\nsum=0 \/\/ \u7528\u5927\u5c0f\u8868\u8fbe\u5f0f\u7684\u65f6\u5019\uff0c\u7528\u53cc\u62ec\u53f7\r\ni=1\r\nwhile (( i <= 100 ))\r\ndo\r\n let \"sum+=i\"\r\n let \"i += 2\"\r\ndone\r\necho \"sum=$sum\" \r\n\r\n#!\/bin\/bash \/\/ while\u3001do\u7684\u5faa\u73af\u6761\u4ef6\uff0c\u53ef\u4ee5\u5199\u5728\u4e00\u884c\uff0c\u7528(())\u6765\u5b9e\u73b0\uff0c[]\u548c[[]]\u4e0d\u53ef\u4ee5\u3002\r\n# Usage:\r\n# Author: Liemer_Lius\r\n#!\/bin\/bash \r\nsum=0\r\nfor(( i = 1; i <= 100; i = i + 2 )); do\r\nlet \"sum += i\"\r\ndone\r\necho \"sum=$sum\" \r\n[root@rs1 ~]# .\/r.sh \r\nsum=2500\r\n<\/code><\/pre>\n\u6ce8\u610f\uff1a\u5f53\u7528(())\u7684\u65f6\u5019\uff0c\u91cc\u9762\u7684\u5185\u5bb9\u624d\u53ef\u4ee5\u7528<>-+=\u7b49\u76f4\u63a5\u5904\u7406\uff0c\u4e14\u53d8\u91cf\u4e0d\u7528\u52a0$\u7b26\u53f7\u3002\u5982\u679c\u662f[]\u6216[[]]\uff0c\u5219\u53ea\u80fd\u4f7f\u7528-eq, -le\u7b49\u7c7b\u578b\u7684\u82f1\u6587\u8868\u8fbe\u65b9\u6cd5\u3002<\/p>\n
8\u3001until\u5faa\u73af<\/h4>\n#!\/bin\/bash\r\n# Usage:\r\n# Date: 2017-12-12\r\n# Author: Liemer_Lius\r\ndeclare -i SUM=0\r\ndeclare -i I=0\r\nuntil [ $I -gt 100 ]; do\r\n let \"SUM+=I\"\r\n let I+=1\r\ndone\r\necho \"Summary: $SUM\"\r\n\r\n[root@rs1 ~]# .\/s.sh \/\/ \u6267\u884c\u7ed3\u679c\r\nSummary: 5050\r\n<\/code><\/pre>\n\u7279\u70b9\uff1a\u548cwhile\u4e00\u6837\uff0c\u9700\u8981\u4e00\u4e2a\u5224\u65ad\u5f00\u5173\uff0c\u548c\u4e00\u4e2a\u4e0d\u65ad\u53d8\u6362\u53c2\u6570\u503c\u7684\u8bed\u53e5\uff0c\u5426\u5219\u5bb9\u6613\u9677\u5165\u6b7b\u5faa\u73af\u3002<\/p>\n
9\u3001shift\u7684\u7528\u6cd5<\/h4>\n
shift\u662f\u5207\u6362$[1-9]\u53d8\u91cf\u7684\uff0c\u4f8b\u5982\uff0c\u811a\u672c\u4e2d\u53ef\u4ee5\u53ea\u6709$1\uff0c\u5229\u7528shift\u6765\u5b9e\u73b0$#\u91cc\u9762\u7684\u9009\u9879\u5207\u6362\u3002<\/p>\n
#!\/bin\/bash\r\n# Usage of shift.\r\nfor i in {1..3}; do\r\n echo $1\r\n shift\r\ndone\r\n# bash switch.sh First Second Third\r\nFirst\r\nSecond\r\nThird\r\n<\/code><\/pre>\n10\u3001break\uff0ccontinue\u7684\u7528\u6cd5<\/h4>\n\u89c1\u7b2c7\u90e8\u5206\uff0cwhile\u5faa\u73af\u7684\u4f8b\u5b50\u3002\r\n\r\nbreak\uff1a\u9000\u51fa\u6574\u4e2a\u5faa\u73af\uff1b\r\n\r\ncontinue\uff1a\u9000\u51fa\u672c\u6b65\u5faa\u73af\uff1b\r\n\r\nexit\uff1a\u9000\u51fa\u811a\u672c\uff1b\r\n\r\n<\/code><\/pre>\n11\u3001return\u3001exit\u7684\u7528\u6cd5<\/h4>\n
return\u662f\u5728\u4e00\u5b9a\u7684\u6761\u4ef6\u4e0b\uff0c\u8fd4\u56de\u4e00\u4e2a\u6267\u884c\u72b6\u6001\u503c\uff0c\u65e0\u8bba\u8fd4\u56de\u7684\u662f\u4ec0\u4e48\uff0c\u6539\u6bb5\u4ee3\u7801\u90fd\u505c\u6b62\u6267\u884c\uff0c\u4e00\u822c\u5e38\u7528\u4e0e\u51fd\u6570\u4e2d\uff0c\u505a\u4e3a\u5176\u4ed6\u4ee3\u7801\u7684\u5224\u65ad\u6761\u4ef6\u3002<\/p>\n
exit\u540e\u9762\u53ef\u4ee5\u8ddf\u4e00\u4e2a\u8fd4\u56de\u503c\u3002exit\u4ee5\u540e\uff0c\u6574\u4e2a\u811a\u672c\u9000\u51fa\uff0c\u5982\u679c\u540e\u9762\u6ca1\u6709\u8fd4\u56de\u503c\u7684\u65f6\u5019\uff0c\u9ed8\u8ba4\u5c06\u6700\u540e\u4e00\u6761\u6267\u884c\u547d\u4ee4\u7684\u8fd4\u56de\u503c\u505a\u4e3aexit\u4ee5\u540e\u7684\u8fd4\u56de\u503c\u3002<\/p>\n
# Usage of ruturn\r\nfunction COMELE {\r\n for J in `seq 0 $[${#ARRAY[@]}-1]`; do\r\n if [ $1 -eq ${ARRAY[$J]} ]; then\r\n return 1\r\n fi\r\n done\r\n return 0\r\n}<\/code><\/pre>\n\u5982\u4e0a\uff0c\u6211\u4e48\u5b9a\u4e49\u4e86\u4e00\u4e2a\u51fd\u6570\u3002\u5f53\u5f15\u7528\u51fd\u6570\u7684\u65f6\u5019\uff0c\u9700\u8981\u51fd\u6570\u5224\u65ad\u7684\u90a3\u4e2a\u503c\uff08$1\uff0c\u51fd\u6570\u540d\u540e\u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\uff09\u5982\u679c\u7b49\u4e8e\u6570\u5217\u4e2d\u7684\u4efb\u610f\u4e00\u4e2a\u503c\u7684\u65f6\u5019\uff0c\u90fd\u8fd4\u56de1\uff1b\u5982\u679c\u5faa\u73af\u7ed3\u675f\u4ee5\u540e\u6ca1\u6709\u5339\u914d\u5230\uff0c\u5219\u6700\u540e\u8fd8\u6709\u4e00\u4e2a\u8fd4\u56de0\u7684\u64cd\u4f5c\u3002\u8fd9\u4e2a\u8fd4\u56de\u503c\u5c06\u4f5c\u4e3a\u540e\u7eed\u4ee3\u7801\u7684\u5224\u65ad\u6761\u4ef6\u3002<\/p>\n
# Usage of \"exit\"\r\ncase $1 in\r\n-a|--add)\r\necho \"Adding...\"\r\n;;\r\n-d|--del)\r\necho \"Deleting...\"\r\n;;\r\n-h|--help)\r\necho \"Usage: `basename $0` -a|--add|-d|--del|-h|--help\"\r\nexit 0\r\n;;\r\n*)\r\necho \"Usage: `basename $0` -a|--add|-d|--del|-h|--help\"\r\nexit 8\r\n;;\r\nesac<\/code><\/pre>\n\u5982\u4e0a\uff0c\u5728-h|–help\u7684\u65f6\u5019\uff0cexit\u7684\u8fd4\u56de\u503c\u662f0\uff0c\u8fd9\u8868\u793a\u6b63\u5e38\u9000\u51fa\uff0c\u56e0\u4e3a\u53c2\u6570\u662f\u6b63\u786e\u7684\uff1b\u800c*\uff09\u7684\u65f6\u5019\uff0c\u8868\u793a\u53c2\u6570\u5199\u7684\u4e0d\u6b63\u786e\uff0c\u8fd9\u65f6\u5019exit\u4ee5\u540e\u8d4b\u4e88\u7684\u8fd4\u56de\u503c\u662f8\uff0c\u8868\u793a\u662f\u9519\u8bef\u9000\u51fa\u3002<\/p>\n
<\/p>\n
\u8f6c\u8f7d\u8bf7\u6ce8\u660e\uff1aliutianfeng.com<\/a> » Shell\u811a\u672c\u57fa\u672c\u7ed3\u6784-if, case, do, while, until<\/a><\/p>","protected":false},"excerpt":{"rendered":"\u65e0\u8bba\u591a\u590d\u6742\u7684\u811a\u672c\uff0c\u90fd\u662f\u7531\u4e00\u4e9b\u57fa\u672c\u7684\u7ed3\u6784\u6784\u6210\u7684\u3002 \u4e0b\u9762\uff0c\u4ecb\u7ecd\u4e00\u4e0b\u57fa\u672c\u7684shell\u811a\u672c\u8bed\u6cd5\uff0c\u5feb\u901f\u6d4f\u89c8\uff0c\u6765\u79d2\u719f\u6089\u57fa\u672c […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[31],"tags":[],"_links":{"self":[{"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=\/wp\/v2\/posts\/322"}],"collection":[{"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=322"}],"version-history":[{"count":13,"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=\/wp\/v2\/posts\/322\/revisions"}],"predecessor-version":[{"id":370,"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=\/wp\/v2\/posts\/322\/revisions\/370"}],"wp:attachment":[{"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=322"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.liutianfeng.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}