macOS NSTask: using multiple pipes for multiple commands

[pcwiz]

I read about 2 methods to run commands like these:

otool -L /Applications/TextEdit.app/Contents/MacOS/TextEdit  | awk 'NR>1{print $1}' | sed -e '/@executable_path/d' -e 's/(.*)$//' -e  's/\/Versions.*$//'

Where multiple commands are combined using pipes. I read about the /bin/sh way where you set the launch path to /bin/sh, the first argument to @"-c", second argument to whatever your command is, and then the 3rd argument to nil (as usual with NSTask). This way did not work for me and did not return an output.

I also read that you can set each command and its arguments individually and then combine them together with multiple NSPipe objects. However, I am confused as to how I would go about doing this. Any help would be appreciated. Thanks

 

[lee1210]

This might be cheating, but you could just take the command, stick it in a .sh file, and run that instead.

-Lee

 

[pcwiz]

Thanks for the suggestion. I created a sh script file with my command and 1 argument ($1):

#!/bin/sh

# Machine readable output of otool

otool -L $1  | awk 'NR>1{print $1}' | sed -e '/@executable_path/d' -e 's/(.*)$//' -e  's/\/Versions.*$//'

And here's my NSTask method:

	NSTask *task;
    task = [[NSTask alloc] init];
    [task setLaunchPath: @"/bin/sh"];
	
    NSArray *arguments;
    arguments = [NSArray arrayWithObjects: @"/Users/pcwiz/Desktop/beasttool.sh", @"/Applications/TextMate.app/Contents/MacOS/TextMate", 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 (@"%@", string);

As you can see I've supplied 3 arguments, the shell script itself, the argument that the script accepts, and the usual "nil". The problem is that this does not return any output. It does return an output when the script is run from Terminal, and I can't figure out the problem.

EDIT: The NSLog at the end isn't even being called so there does seem to be a problem with something before it. There are no build errors/warnings, and nothing in the console either.

Thanks

EDIT2: The "/bin/sh -c" method that people use with NSTask does not work at all for me. I tried a simple ls /Volumes command like this:

- (IBAction)runTask:(id)sender {
	NSLog(@"hi!");
	NSTask *task;
    task = [[NSTask alloc] init];
    [task setLaunchPath: @"/bin/sh"];
	
    NSArray *arguments;
    arguments = [NSArray arrayWithObjects: @"-c", "ls /Volumes", 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 (@"got\n%@", string);
}

And it resulted in a crash.