NSTask not picking up $PATH from the user's environment

Question

I don't know why this method returns a blank string:

- (NSString *)installedGitLocation {
    NSString *launchPath = @"/usr/bin/which";

    // Set up the task
    NSTask *task = [[NSTask alloc] init];
    [task setLaunchPath:launchPath];
    NSArray *args = [NSArray arrayWithObject:@"git"];
    [task setArguments:args];

    // Set the output pipe.
    NSPipe *outPipe = [[NSPipe alloc] init];
    [task setStandardOutput:outPipe];

    [task launch];

    NSData *data = [[outPipe fileHandleForReading] readDataToEndOfFile];
    NSString *path = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];

    return path;
}

If instead of passing @"git" as the argument, I pass @"which" I get /usr/bin/which returned as expected. So at least the principle works.

from the terminal

$ which which
$ /usr/bin/which
$
$ which git
$ /usr/local/git/bin/git

So it works there.

The only thing I can think of is that which isn't searching through all the paths in my environment.

This is driving me crazy! Does anyone have any ideas?

EDIT: It looks like this is about setting up either NSTask or the user's shell (e.g., ~/.bashrc) so that the correct environment ($PATH) is seen by NSTask.

Answer 1

Try,

    [task setLaunchPath:@"/bin/bash"];
    NSArray *args = [NSArray arrayWithObjects:@"-l",
                     @"-c",
                     @"which git",
                     nil];
    [task setArguments: args];

This worked for me on Snow Leopard; I haven't tested on any other system. The -l (lowercase L) tells bash to "act as if it had been invoked as a login shell", and in the process it picked up my normal $PATH. This did not work for me if the launch path was set to /bit/sh, even with -l.