Executing a command from Objective C

Question

I want to execute a command from objective C (Cocoa framework). The command I am trying is as below. I tried with NSTask but it says "launch path not accessible" when I execute it.

sudo ifconfig en0 down

My code is:

- (void)testme {
NSTask *task;
task = [[NSTask alloc] init];
[task setLaunchPath: @"sudo ifconfig en0 down"];

NSArray *arguments;
arguments = [NSArray arrayWithObjects: @"foo", @"bar.txt", nil];
[task setArguments: arguments];

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

NSFileHandle *file;
file = [pipe fileHandleForReading];

[task launch];

NSData *data;
data = [file readDataToEndOfFile];

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

[string release];
[task release];

}

user149341 · Accepted Answer · 2013-01-29 22:28:49Z

5

sudo ifconfig en0 down is not a sensible launch path. The correct launch path for this command would be /usr/sbin/sudo.

Once that is done, you still need to pass the correct arguments to setArguments:. foo and bar.txt look like example code that you copied without reading.

MORE IMPORTANTLY, THOUGH, running sudo from NSTask will not work. You will need to use Authorization Services to launch a privileged command.

answered Jan 29, 2013 at 22:28

user149341

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2 Comments

Abhinav Over a year ago

Ok. I could run it via " char *command = "sudo ifconfig en0 down"; system(command);" but it asks me system admin credentials. Any idea how to get rid of it?

user149341 Over a year ago

You can't. Use Authorization Services.

user529758 · Accepted Answer · 2013-01-29 22:29:23Z

1

You need to specify the full executable path and you should specify the arguments as the arguments, not along with the launch path. NSTask ain't a shell, it internally uses syscalls (execv(), I guess) to invoke the command.

NSTask *task = [[NSTask alloc] init];
[task setLaunchPath:@"/usr/bin/sudo"];

NSArray *arguments = @[@"ifconfig", @"en0", @"down"];
[task setArguments:arguments];

answered Jan 29, 2013 at 22:29

user529758

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