ShellTask.m

//
//  ShellTask.m
//  
//
//  Created by Vincent Gable on 6/1/07.
//  Copyright 2007 Vincent Gable, you're free to use this code in *any* way you like, but I'd really appreciate it if you told me what you used it for.  It could make my day.
//

#import "ShellTask.h"

@implementation ShellTask


//Returns an NSTask that is equvalent to 
// sh -c <command>
//where <command> is passed directly to sh via argv, and is NOT quoted (so ~ expansion still works).
//stdin for the task is set to /dev/null .
//Note that the PWD for the task is whatever the current PWD for the executable sending the taskForCommand: message.
//Sending the task a - launch message will tell sh to run it.
+ (NSTask*) taskForShellCommand:(NSString*)command
{
    NSTask *task = [[[NSTask alloc] init] autorelease]; 
    [task setLaunchPath: @"/bin/sh"]; //we are launching sh, it is wha will process command for us
    [task setStandardInput:[NSFileHandle fileHandleWithNullDevice]]; //stdin is directed to /dev/null
    
    
    NSArray	*args = [NSArray arrayWithObjects:	@"-c", //-c tells sh to execute commands from the next argument
                         command, //sh will read and execute the commands in this string.
                         nil];
    [task setArguments: args];
    
    return task;
}


//Executes the shell command, command, waits for it to finish
//returning it's output to std in and stderr.
//
//NOTE: may deadlock under some circumstances if the output gets so big it fills the pipe.
//See http://dev.notoptimal.net/search/label/NSTask for an overview of the problem, and a solution.
//I have not experienced the problem myself, so I canÕt comment.
+ (NSString*) executeShellCommandSynchronously:(NSString*)command
{
    NSTask *task = [self taskForShellCommand:command];
    
    //we pipe stdout and stderr into a file handle that we read to 
    NSPipe *outputPipe = [NSPipe pipe];
    [task setStandardOutput: outputPipe];
    [task setStandardError: outputPipe];
    NSFileHandle *outputFileHandle = [outputPipe fileHandleForReading];
    
    [task launch];
    
    return [[[NSString alloc] initWithData:[outputFileHandle readDataToEndOfFile] encoding: NSUTF8StringEncoding] autorelease];
}

+ (oneway void) executeShellCommandAsynchronously:(NSString*)command
{
    //  [[self taskForShellCommand:command] launch];
    
    
    // Jordan's reimplementation here, so we can read the output in the background and show the user the output!!
    NSTask *task = [self taskForShellCommand:command];
    
    //we pipe stdout and stderr into a file handle that we read to 
    NSPipe *outputPipe = [NSPipe pipe];
    [task setStandardOutput: outputPipe];
    [task setStandardError: outputPipe];
    NSFileHandle *outputFileHandle = [outputPipe fileHandleForReading];    
    
    
    // We need to read in background and notify!!!!!
    [outputFileHandle readInBackgroundAndNotify];
    
    [task launch];
    
    
    return;
}

@end