\u901a\u5e38\u6211\u4eec\u4f7f\u7528\u4e86fork\u51fd\u6570\u521b\u5efa\u4e86\u4e00\u4e2a\u5b50\u8fdb\u7a0b\u540e\uff0c\u5b50\u8fdb\u7a0b\u4f1a\u8c03\u7528exec\u65cf\u51fd\u6570\u6267\u884c\u53e6\u5916\u4e00\u4e2a\u7a0b\u5e8f\u3002\u7531\u4e8efork\u51fd\u6570\u65b0\u5efa\u7684\u5b50\u8fdb\u7a0b\u548c\u7236\u8fdb\u7a0b\u51e0\u4e4e\u4e00\u6a21\u4e00\u6837\uff08\u4e0d\u8fc7\uff0c\u540e\u6765\u5f15\u5165\u4e86\u5199\u65f6\u590d\u5236\u6280\u672f\u907f\u514d\u4e86\u8fd9\u4e00\u70b9\uff09\uff0c\u56e0\u6b64\u9700\u8981\u4f7f\u7528exec\u51fd\u6570\u4f7f\u5f97\u5b50\u8fdb\u7a0b\u6267\u884c\u4e00\u4e2a\u65b0\u7684\u53ef\u6267\u884c\u7a0b\u5e8f\u3002<\/p>\n
\u6211\u4eec\u4e4b\u6240\u4ee5\u79f0exec\u4e3a\u65cf\u51fd\u6570\u662f\u56e0\u4e3a\u5b83\u67096\u79cd\u4e0d\u540c\u7684\u5f62\u5f0f\uff0c\u4e3b\u8981\u533a\u522b\u4f53\u73b0\u5728\u53c2\u6570\u4e0a\uff1a<\/p>\n
#include <unistd.h>;\r\nextern char **environ;\r\nint execl(const char *path, const char *arg, ...);\r\nint execlp(const char *file, const char *arg, ...);\r\nint execle(const char *path, const char *arg,\r\n ..., char * const envp[]);\r\nint execv(const char *path, char *const argv[]);\r\nint execvp(const char *file, char *const argv[]);\r\nint execve(const char *filename, char *const argv[],\r\n char *const envp[]);<\/pre>\n\u603b\u4f53\u6765\u8bf4\uff0cexec\u65cf\u51fd\u6570\u7684\u53c2\u6570\u5206\u4e3a\u4e09\u7c7b\uff1a\u6587\u4ef6\u8def\u5f84\uff0c\u547d\u4ee4\u884c\u53c2\u6570\uff0c\u73af\u5883\u53d8\u91cf\u3002\u4e0d\u8bba\u90a3\u4e2aexec\u51fd\u6570\uff0c\u6700\u7ec8\u90fd\u662f\u5c06\u4e0a\u8ff0\u4e09\u7c7b\u53c2\u6570\u4f20\u9012\u7ed9\u53ef\u6267\u884c\u7a0b\u5e8f\u4e2d\u7684main\u51fd\u6570\u3002\u8fd9\u91cc\u6709\u4e00\u4e2a\u65b0\u7684\u6982\u5ff5\uff0c\u5373\u73af\u5883\u53d8\u91cf\uff0c\u5b83\u5b9a\u4e49\u4e86\u7528\u6237\u7684\u5de5\u4f5c\u73af\u5883\uff0c\u5305\u62ec\u7528\u6237\u7684\u4e3b\u76ee\u5f55\uff0c\u7ec8\u7aef\u7684\u7c7b\u578b\uff0c\u5f53\u524d\u7528\u6237\uff0c\u5f53\u524d\u76ee\u5f55\u7b49\u4fe1\u606f\u3002\u4e8b\u5b9e\u4e0a\uff0cmain\u51fd\u6570\u7684\u5b8c\u6574\u5f62\u5f0f\u5e94\u8be5\u662f\uff1a<\/p>\n
int main(int argc, char *argv[], char **envp);<\/pre>\n\u901a\u5e38\u6211\u4eec\u5e76\u6ca1\u6709\u663e\u793a\u6307\u5b9a\u73af\u5883\u53d8\u91cf\uff0c\u8fd9\u662f\u56e0\u4e3amain\u51fd\u6570\u6bcf\u6b21\u90fd\u9ed8\u8ba4\u4f7f\u7528\u7cfb\u7edf\u81ea\u5b9a\u4e49\u7684\u5168\u5c40\u53d8\u91cfenviron\u3002\u53e6\u5916\uff0c\u901a\u8fc7\u5728\u7ec8\u7aef\u8f93\u5165env\u547d\u4ee4\uff0c\u4e5f\u53ef\u67e5\u770b\u5f53\u524d\u7684\u6240\u6709\u73af\u5883\u53d8\u91cf\u4fe1\u606f\u3002\u53ef\u4ee5\u770b\u5230\uff0cmain\u51fd\u6570\u4e2d\u7684argv[]\u548cenvp\u4e0eexec\u51fd\u6570\u7684\u53c2\u6570\u6709\u5bf9\u5e94\u5173\u7cfb\u3002<\/p>\n
\u521d\u6b21\u63a5\u89e6exec\u65cf\u51fd\u6570\uff0c\u6613\u88ab\u8fd96\u79cd\u4e0d\u540c\u7684\u8c03\u7528\u5f62\u5f0f\u641e\u5f97\u6df7\u4e71\u3002\u4e0b\u9762\u6211\u4eec\u5c06\u4f9d\u6b21\u4ece\u4e0a\u8ff0\u4e09\u4e2a\u53c2\u6570\u7684\u89d2\u5ea6\u6765\u533a\u5206\u8fd9\u4e9b\u51fd\u6570\u7684\u7ec6\u5fae\u533a\u522b\u3002<\/p>\n
1.\u53ef\u6267\u884c\u6587\u4ef6\u7684\u8def\u5f84<\/strong><\/p>\n
\u4ee5p\u7ed3\u5c3e\u7684exec\u51fd\u6570\u53ef\u4ee5\u76f4\u63a5\u4f20\u9012\u53ef\u6267\u884c\u7a0b\u5e8f\u7684\u6587\u4ef6\u540d\uff0c\u6b64\u65f6\u8fd9\u7c7b\u51fd\u6570\u4f1a\u81ea\u52a8\u5728PATH\u73af\u5883\u53d8\u91cf\u6240\u6307\u5b9a\u7684\u76ee\u5f55\u4e0b\u67e5\u627e\u8fd9\u4e2a\u53ef\u6267\u884c\u6587\u4ef6\uff1b\u975ep\u7ed3\u5c3e\u7684exec\u51fd\u6570\u5219\u5fc5\u987b\u663e\u793a\u6307\u5b9a\u53ef\u6267\u884c\u7a0b\u5e8f\u7684\u5b8c\u6574\u8def\u5f84\uff1b<\/p>\n
2.\u547d\u4ee4\u884c\u53c2\u6570<\/strong><\/p>\n
\u4ee5execl\u5f00\u59cb\u7684exec\u51fd\u6570\u5fc5\u987b\u4ee5\u5217\u8868\u7684\u5f62\u5f0f\u4f20\u9012\u6240\u6709\u7684\u547d\u4ee4\u884c\u53c2\u6570\uff0c\u5e76\u4e14\u6700\u7ec8\u4ee5NULL\u4f5c\u4e3a\u547d\u4ee4\u884c\u53c2\u6570\u7684\u7ed3\u675f\uff1b\u800c\u4ee5execv\u5f00\u59cb\u7684exec\u51fd\u6570\u5219\u4ee5\u5b57\u7b26\u4e32\u6307\u9488\u6570\u7ec4\u7684\u5f62\u5f0f\u4f20\u9012\u6240\u6709\u547d\u4ee4\u884c\u53c2\u6570\uff1b<\/p>\n
3.\u73af\u5883\u53d8\u91cf<\/strong><\/p>\n
\u4ee5e\u7ed3\u5c3e\u7684exec\u51fd\u6570\u5fc5\u987b\u663e\u793a\u6307\u5b9a\u73af\u5883\u53d8\u91cf\uff1b\u800c\u975ep\u7ed3\u5c3e\u7684exec\u51fd\u6570\u5219\u4f7f\u7528\u9ed8\u8ba4\u7684\u73af\u5883\u53d8\u91cf\uff0c\u4e5f\u5c31\u662fmain\u51fd\u6570\u4e2d\u7684\u73af\u5883\u53d8\u91cf\uff1b<\/p>\n
\u867d\u7136exec\u51fd\u6570\u67096\u79cd\u4e0d\u540c\u7684\u8c03\u7528\u5f62\u5f0f\uff0c\u4f46\u662f\u6bcf\u4e2a\u51fd\u6570\u5b9e\u73b0\u7684\u529f\u80fd\u90fd\u662f\u4e00\u6837\u7684\uff0c\u5373\u5b8c\u6210\u65b0\u7684\u53ef\u6267\u884c\u7a0b\u5e8f\u7684\u88c5\u5165\u3002\u4e0b\u9762\u7684\u8fd9\u4e2a\u7a0b\u5e8f\u5f88\u597d\u7684\u6f14\u793a\u4e86\u4e0d\u540cexec\u51fd\u6570\u7684\u4f7f\u7528\u65b9\u6cd5\uff1a<\/p>\n
#include < unistd.h >\r\n#include < stdio.h >\r\n\r\nint main()\r\n{\r\n\tchar *envp[]={\r\n\t\t\"PATH = \/tmp\",\r\n\t \"USER = edsionte\",\r\n\t\tNULL\r\n\t};\r\n\r\n\tchar *argv_execv[] = {\"echo\", \"excuted by execv\", NULL};\r\n\tchar *argv_execvp[] = {\"echo\", \"executed by execvp\", NULL};\r\n\tchar *argv_execve[] = {\"env\", NULL};\r\n\r\n\tif (fork() == 0)\r\n\t\tif(execl(\"\/bin\/echo\", \"echo\", \"executed by execl\", NULL) < 0)\r\n\t\t\tperror(\"Err on execl\");\r\n\tif(fork() == 0)\r\n\t\tif(execlp(\"echo\", \"echo\", \"executed by execlp\", NULL) < 0)\r\n\t\t\tperror(\"Err on execlp\");\r\n\tif(fork() == 0)\r\n\t\tif(execle(\"\/usr\/bin\/env\", \"env\", NULL, envp) < 0)\r\n\t\t\tperror(\"Err on execle\");\r\n\tif(fork() == 0)\r\n\t\tif(execv(\"\/bin\/echo\", argv_execv) < 0)\r\n\t\t\tperror(\"Err on execv\");\r\n\tif(fork() == 0)\r\n\t\tif(execvp(\"echo\", argv_execvp) < 0)\r\n\t\t\tperror(\"Err on execvp\");\r\n\tif(fork() == 0)\r\n\t\tif(execve(\"\/usr\/bin\/env\", argv_execve, envp) < 0)\r\n\t\t\tperror(\"Err on execve\");\r\n\r\n\tprintf(\"goodbye!\\n\");\r\n\treturn 0;\r\n}\r\n\/\/\u7ed3\u679c\uff1a\r\nedsionte@edsionte-desktop:~\/edsionte$ .\/sys_process\r\ngoodbye!\r\nedsionte@edsionte-desktop:~\/edsionte$ executed by execl\r\nexcuted by execv\r\nexecuted by execvp\r\nexecuted by execlp\r\nPATH = \/tmp\r\nUSER = edsionte\r\nPATH = \/tmp\r\nUSER = edsionte<\/pre>\n\u8fd9\u4e2a\u7a0b\u5e8f\u5206\u522b\u4f7f\u7528\u4e0d\u540c\u7684exec\u51fd\u6570\u8c03\u7528\u4e86echo\u6216env\u547d\u4ee4\uff0c\u5e76\u6839\u636e\u6240\u4f20\u9012\u7684\u4e0d\u540c\u53c2\u6570\u663e\u793a\u4e0d\u540c\u7ed3\u679c\u3002\u8be5\u7a0b\u5e8f\u53ef\u80fd\u6bcf\u6b21\u8fd0\u884c\u540e\u7684\u663e\u793a\u987a\u5e8f\u90fd\u6709\u6240\u4e0d\u540c\uff0c\u8fd9\u662f\u8fdb\u7a0b\u7684\u5e76\u53d1\u6027\u6240\u5bfc\u81f4\u7684\u3002<\/p>\n
\u503c\u5f97\u6ce8\u610f\u7684\u662f\uff0c\u6211\u4eec\u901a\u5e38\u6240\u8bf4\u7684\u547d\u4ee4\u884c\u53c2\u6570\u662f\u4ee5argv\u6570\u7ec4\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u5f00\u59cb\u7684\uff0c\u800c\u7b2c0\u53f7\u5143\u7d20\u662f\u53ef\u6267\u884c\u7a0b\u5e8f\u7684\u540d\u79f0\u3002\u4ee5\u7b2c\u4e00\u4e2aif\u8bed\u53e5\u4e3a\u4f8b\uff0cexecl\u51fd\u6570\u4e3a\/bin\u76ee\u5f55\u4e0b\u7684echo\u7a0b\u5e8f\u4f20\u9012\u4e86\u4e24\u4e2a\u53c2\u6570\uff1a”echo”\u548c”executed by execl”\u3002\u7531\u4e8e\u6211\u4eec\u901a\u8fc7execl\u51fd\u6570\u5df2\u7ecf\u88c5\u5165\u4e86\/bin\/echo\u7a0b\u5e8f\uff0c\u56e0\u6b64\u5728\u8c03\u7528execl\u51fd\u6570\u65f6\uff0c\u7b2c\u4e00\u4e2a\u53c2\u6570”echo”\u53ef\u4ee5\u66ff\u6362\u6210\u4efb\u610f\u5b57\u7b26\u4e32\uff0c\u4f46\u662f\u8fd9\u5e76\u4e0d\u4ee3\u8868\u5c31\u4e0d\u9700\u8981\u4f20\u9012\u8be5\u53c2\u6570\u3002<\/p>\n
\u6211\u4eec\u4e5f\u53ef\u4ee5\u8ba9exec\u51fd\u6570\u53bb\u6267\u884c\u6211\u4eec\u81ea\u5df1\u7f16\u5199\u7684\u53ef\u6267\u884c\u7a0b\u5e8f\u3002\u4e0b\u9762\u8fd9\u4e2a\u4f8b\u5b50\u5f88\u597d\u7684\u6f14\u793a\u4e86\u7236\u8fdb\u7a0b\u548c\u5b50\u8fdb\u7a0b\u7684\u5173\u7cfb\uff1a<\/p>\n
\/*\r\n *Author: edsionte\r\n *Email: edsionte@gmail.com\r\n *Time: 2011\/03\/14\r\n*\/\r\n\r\n#include < stdio.h >\r\n#include < unistd.h >\r\n#include < stdlib.h >\r\n\r\nint main()\r\n{\r\n\tint pid;\r\n\tint val = 0;\r\n\r\n\tpid = fork();\r\n\tif (pid == 0) {\r\n\t\t\/\/child proces;\r\n\t\tprintf(\"[Child %d] I will be a new process!\\n\", getpid());\r\n\t\tif (execl(\".\/sleeping\",\"first arg\", \"20\", NULL) == -1) {\r\n\t\t\tprintf(\"execl error!\\n\");\r\n\t\t\texit(1);\r\n\t\t}\r\n\t\tprintf(\"[Child %d] I never go here!\\n\", getpid());\r\n\t} else if (pid > 0) {\r\n\t\tprintf(\"[Parent %d] I am running!\\n\", getpid());\r\n\t\t\/*\r\n\t\twait(&val);\r\n\t\tprintf(\"[Parent %d] All my child were leaving..\\n\", getpid());\r\n\t\t*\/\r\n\t} else {\r\n\t\tprintf(\"fork error!\\n\");\r\n\t\texit(1);\r\n\t}\r\n\r\n\tprintf(\"[process %d] I am leaving..\\n\", getpid());\r\n\treturn 0;\r\n}\r\n\/\/sleeping.c\u7a0b\u5e8f\r\n#include < stdio.h >\r\n#include < unistd.h >\r\n\r\nint main(int argc, char** argv)\r\n{\r\n\tint sec;\r\n\r\n\tsec = atoi(argv[1]);\r\n\twhile (sec != 0) {\r\n\t\tsleep(1);\r\n\t\tprintf(\"[New Child %d] I am running and my parent is %d\\n\", getpid(), getppid());\r\n\t\tsec--;\r\n\t}\r\n\r\n\treturn 0;\r\n}<\/pre>\n\u8be5\u7a0b\u5e8f\u4f7f\u7528\u4e86\u4e0e\u8fdb\u7a0b\u6709\u5173\u7684\u56db\u4e2a\u6700\u57fa\u672c\u7684\u7cfb\u7edf\u8c03\u7528\u51fd\u6570\uff1afork(),exec(),wait()\u548cexit()\u3002\u5bf9\u4e8e\u8be5\u7a0b\u5e8f\u7684\u5177\u4f53\u5206\u6790\u5982\u4e0b\uff1a<\/p>\n
1.\u7236\u8fdb\u7a0b\u901a\u8fc7fork\u51fd\u6570\u521b\u5efa\u5b50\u8fdb\u7a0b\uff0c\u7136\u540e\u7236\u8fdb\u7a0b\u6253\u5370\u81ea\u5df1\u7684pid\uff1b<\/p>\n
2.\u5b50\u8fdb\u7a0b\u9996\u5148\u6253\u5370\u81ea\u5df1\u7684pid\uff0c\u518d\u901a\u8fc7execve\u51fd\u6570\u88c5\u5165\u53ef\u6267\u884c\u7a0b\u5e8fsleeping\uff0c\u5e76\u901a\u8fc7execve\u51fd\u6570\u5411sleeping\u4f20\u9012\u4e86\u4e00\u4e2a\u53c2\u6570\u201c20\u201d\uff1b<\/p>\n
3.\u5728sleeping\u7a0b\u5e8f\u4e2d\uff0c\u5c06\u4e3b\u51fd\u6570\u4e2d\u4f20\u9012\u7684\u53c2\u6570\u4f5c\u4e3a\u8ba1\u6570\u5668\uff0c\u5e76\u4f9d\u6b21\u5faa\u73af\u7761\u772020s\u3002\u5e76\u4e14\u5faa\u73af\u6253\u5370\u5f53\u524d\u7684sleeping\u8fdb\u7a0b\u7684pid\u4ee5\u53ca\u5176\u7236\u8fdb\u7a0bpid\uff1b<\/p>\n
4.\u7531\u4e8e\u7236\u8fdb\u7a0b\u5148\u4e8e\u5b50\u8fdb\u7a0b\u9000\u51fa\uff0c\u5219sleeping\u8fdb\u7a0b\u6210\u4e3a\u5b64\u513f\u8fdb\u7a0b\uff0c\u56e0\u6b64\u5728sleeping\u6253\u5370\u7684\u7236\u8fdb\u7a0bpid\u4e3a1\uff1b\u5982\u679c\u53bb\u6389\u7a0b\u5e8f\u4e2d\u7684\u6ce8\u91ca\u90e8\u5206\uff0c\u5219\u7236\u8fdb\u7a0b\u7b49\u5f85\u5b50\u8fdb\u7a0b\u9000\u51fa\u540e\u518d\u9000\u51fa\uff0c\u90a3\u4e48sleeping\u6240\u6253\u5370\u7684\u7236\u8fdb\u7a0bpid\u5373\u4e3a\u7236\u8fdb\u7a0b\u7684pid\uff1b<\/p>\n
5.\u5982\u679c\u5b50\u8fdb\u7a0b\u6267\u884cexec\u51fd\u6570\u6210\u529f\uff0c\u5219\u4e3b\u7a0b\u5e8f\u4e2d\u6700\u540e\u4e00\u6761\u8bed\u53e5\u5c31\u4e0d\u4f1a\u88ab\u5b50\u8fdb\u7a0b\u6267\u884c\u3002\u8bf4\u660e\u5b50\u8fdb\u7a0b\u5728\u6267\u884c\u4e86exec\u51fd\u6570\u540e\u5c31\u4e0e\u7236\u8fdb\u7a0b\u5b8c\u5168\u8131\u79bb\u3002\u53e6\u5916\uff0c\u5728\u5b50\u8fdb\u7a0b\u6267\u884c\u8fc7\u7a0b\u4e2d\u4e5f\u53ef\u4ee5\u901a\u8fc7ps\u547d\u4ee4\u67e5\u770b\u5f53\u524d\u7684\u8fdb\u7a0b\u5b58\u5728\u60c5\u51b5\uff1b<\/p>\n
\u53c2\u8003\uff1a<\/strong><\/em><\/p>\n
1.http:\/\/www.ibm.com\/developerworks\/cn\/linux\/kernel\/syscall\/part3\/<\/strong><\/em><\/p>\n
2.Linux C\u7f16\u7a0b\u5b9e\u6218\uff1b\u7ae5\u6c38\u6e05 \u8457\uff1b\u4eba\u6c11\u90ae\u7535\u51fa\u7248\u793e\uff1b<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
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