做越獄應(yīng)用和插件開發(fā)，經(jīng)常會(huì)調(diào)用 system 去執(zhí)行系統(tǒng)命令，早在 Xcode 7，使用 system 函數(shù)提示警告：

'system' is deprecated: first deprecated in iOS 8.0 - Use posix_spawn APIs installd

只是警告，還是可以正常編譯和使用，但是升級(jí)到 Xcode 9，system 函數(shù)就從 SDK 中移除了，不能再使用了，提示：

'system' is unavailable: not available on iOS

替代的方法一般有三種，第一種是使用 posix_spawn，代碼如下：

pid_t pid; char *argv[] = {"/bin/ls", //path"-al", //parameter1"/", //parameter2NULL };posix_spawn(&pid, argv[0], NULL, NULL, argv, NULL);printf("pid=%d,child pid = %d\n",getpid(),pid);int stat; waitpid(pid,&stat,0); printf("stat is %d\n",stat);

第二種是使用 NSTask，代碼如下：

NSTask *task = [[NSTask alloc] init]; task.launchPath = @"/bin/ls"; task.arguments = [NSArray arrayWithObjects:@"-al",@"/",nil]; [task launch]; [task waitUntilExit];

NSTask.h 頭文件信息如下：

#import <Foundation/NSObject.h>@class NSString, NSArray, NSDictionary;@interface NSTask : NSObject// Create an NSTask which can be run at a later time // An NSTask can only be run once. Subsequent attempts to // run an NSTask will raise. // Upon task death a notification will be sent // { Name = NSTaskDidTerminateNotification; object = task; } //- (instancetype)init;// set parameters // these methods can only be done before a launch // if not set, use current // if not set, use current// set standard I/O channels; may be either an NSFileHandle or an NSPipe - (void)setStandardInput:(id)input; - (void)setStandardOutput:(id)output; - (void)setStandardError:(id)error;// get parameters @property (NS_NONATOMIC_IOSONLY, copy) NSString *launchPath; @property (NS_NONATOMIC_IOSONLY, copy) NSArray *arguments; @property (NS_NONATOMIC_IOSONLY, copy) NSDictionary *environment; @property (NS_NONATOMIC_IOSONLY, copy) NSString *currentDirectoryPath;// get standard I/O channels; could be either an NSFileHandle or an NSPipe - (id)standardInput; - (id)standardOutput; - (id)standardError;// actions - (void)launch;- (void)interrupt; // Not always possible. Sends SIGINT. - (void)terminate; // Not always possible. Sends SIGTERM.@property (NS_NONATOMIC_IOSONLY, readonly) BOOL suspend; @property (NS_NONATOMIC_IOSONLY, readonly) BOOL resume;// status @property (NS_NONATOMIC_IOSONLY, readonly) int processIdentifier; @property (NS_NONATOMIC_IOSONLY, getter=isRunning, readonly) BOOL running;@property (NS_NONATOMIC_IOSONLY, readonly) int terminationStatus;@end@interface NSTask (NSTaskConveniences)+ (NSTask *)launchedTaskWithLaunchPath:(NSString *)path arguments:(NSArray *)arguments; // convenience; create and launch- (void)waitUntilExit; // poll the runLoop in defaultMode until task completes@endFOUNDATION_EXPORT NSString * const NSTaskDidTerminateNotification;

如果非要調(diào)用 system 函數(shù)不可，那就使用第三種方法，找到 system 函數(shù)地址直接調(diào)用，方法參見:?動(dòng)態(tài)調(diào)用函數(shù)，具體代碼如下：

typedef int (*my_system) (const char *str); int call_system(const char *str){//動(dòng)態(tài)庫路徑char *dylib_path = "/usr/lib/libSystem.dylib";//打開動(dòng)態(tài)庫void *handle = dlopen(dylib_path, RTLD_GLOBAL | RTLD_NOW);if (handle == NULL) {//打開動(dòng)態(tài)庫出錯(cuò)fprintf(stderr, "%s\n", dlerror());} else {//獲取 system 地址my_system system = dlsym(handle, "system");//地址獲取成功則調(diào)用if (system) {int ret = system(str);return ret;}dlclose(handle); //關(guān)閉句柄}return -1; }

這樣 call_system 函數(shù)就相當(dāng)于 system 的功能了，替換即可。

原文地址：https://www.exchen.net/ios-hacker-system-%E5%87%BD%E6%95%B0%E8%A2%AB%E5%BA%9F%E9%99%A4%E7%9A%84%E6%9B%BF%E4%BB%A3%E6%96%B9%E6%B3%95.html

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