还有一个很好的老式POSIX系统("echo -en '\007'");

你可以使用NSTask。下面是一个运行'/usr/bin/grep foo bar.txt'的例子。

int pid = [[NSProcessInfo processInfo] processIdentifier];
NSPipe *pipe = [NSPipe pipe];
NSFileHandle *file = pipe.fileHandleForReading;

NSTask *task = [[NSTask alloc] init];
task.launchPath = @"/usr/bin/grep";
task.arguments = @[@"foo", @"bar.txt"];
task.standardOutput = pipe;

[task launch];

NSData *data = [file readDataToEndOfFile];
[file closeFile];

NSString *grepOutput = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
NSLog (@"grep returned:\n%@", grepOutput);

nspope和NSFileHandle用于重定向任务的标准输出。

有关在Objective-C应用程序中与操作系统交互的更详细信息，您可以查看Apple开发中心的这篇文档:与操作系统交互。

编辑:包括修复NSLog问题

如果你正在使用NSTask通过bash运行命令行实用程序，那么你需要包括这条神奇的行来保持NSLog工作:

//The magic line that keeps your log where it belongs
task.standardOutput = pipe;

解释在这里:https://web.archive.org/web/20141121094204/https://cocoadev.com/HowToPipeCommandsWithNSTask

肯特的文章给了我一个新想法。这个runCommand方法不需要脚本文件，只需要用一行来运行命令:

- (NSString *)runCommand:(NSString *)commandToRun
{
    NSTask *task = [[NSTask alloc] init];
    [task setLaunchPath:@"/bin/sh"];

    NSArray *arguments = [NSArray arrayWithObjects:
                          @"-c" ,
                          [NSString stringWithFormat:@"%@", commandToRun],
                          nil];
    NSLog(@"run command:%@", commandToRun);
    [task setArguments:arguments];

    NSPipe *pipe = [NSPipe pipe];
    [task setStandardOutput:pipe];

    NSFileHandle *file = [pipe fileHandleForReading];

    [task launch];

    NSData *data = [file readDataToEndOfFile];

    NSString *output = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    return output;
}

你可以这样使用这个方法:

NSString *output = runCommand(@"ps -A | grep mysql");

Objective-C (Swift见下文)

清理顶部答案中的代码，使其更具可读性，减少冗余，增加单行方法的好处，并使其成为NSString类别

@interface NSString (ShellExecution)
- (NSString*)runAsCommand;
@end

实现:

@implementation NSString (ShellExecution)

- (NSString*)runAsCommand {
    NSPipe* pipe = [NSPipe pipe];

    NSTask* task = [[NSTask alloc] init];
    [task setLaunchPath: @"/bin/sh"];
    [task setArguments:@[@"-c", [NSString stringWithFormat:@"%@", self]]];
    [task setStandardOutput:pipe];

    NSFileHandle* file = [pipe fileHandleForReading];
    [task launch];

    return [[NSString alloc] initWithData:[file readDataToEndOfFile] encoding:NSUTF8StringEncoding];
}

@end

用法:

NSString* output = [@"echo hello" runAsCommand];

如果你在输出编码方面有问题:

// Had problems with `lsof` output and Japanese-named files, this fixed it
NSString* output = [@"export LANG=en_US.UTF-8;echo hello" runAsCommand];

希望它对你和未来的我一样有用。(嗨,你!)

斯威夫特4

下面是一个使用管道、进程和字符串的Swift示例

extension String {
    func run() -> String? {
        let pipe = Pipe()
        let process = Process()
        process.launchPath = "/bin/sh"
        process.arguments = ["-c", self]
        process.standardOutput = pipe

        let fileHandle = pipe.fileHandleForReading
        process.launch()

        return String(data: fileHandle.readDataToEndOfFile(), encoding: .utf8)
    }
}

用法:

let output = "echo hello".run()

或者因为Objective C只是C，上面有一些OO层，你可以使用posix对等物:

int execl(const char *path, const char *arg0, ..., const char *argn, (char *)0);
int execle(const char *path, const char *arg0, ..., const char *argn, (char *)0, char *const envp[]);
int execlp(const char *file, const char *arg0, ..., const char *argn, (char *)0);
int execlpe(const char *file, const char *arg0, ..., const char *argn, (char *)0, char *const envp[]);
int execv(const char *path, char *const argv[]);
int execve(const char *path, char *const argv[], char *const envp[]);
int execvp(const char *file, char *const argv[]);
int execvpe(const char *file, char *const argv[], char *const envp[]); 

它们包含在unistd.h头文件中。

fork, exec和wait应该有用，如果你不是在寻找Objective-C特定的方法。Fork创建当前运行程序的副本，exec用一个新程序替换当前运行的程序，然后wait等待子进程退出。例如(没有任何错误检查):

#include <stdlib.h>
#include <unistd.h>

pid_t p = fork();
if (p == 0) {
    /* fork returns 0 in the child process. */
    execl("/other/program/to/run", "/other/program/to/run", "foo", NULL);
} else {
    /* fork returns the child's PID in the parent. */
    int status;
    wait(&status);
    /* The child has exited, and status contains the way it exited. */
}

/* The child has run and exited by the time execution gets to here. */

还有一个系统，它运行命令，就像您从shell的命令行输入命令一样。这样更简单，但你对情况的控制力更弱。

我假设你正在使用一个Mac应用程序，所以这些链接指向苹果关于这些函数的文档，但它们都是POSIX，所以你应该在任何POSIX兼容的系统上使用它们。