NSTask and wildcard problem ?

Why launching a NSTask with parameters including some wildcards doesnt' work, while the same command in Terminal.app works perfectly ?
This is because wild card expansion is done by the running shell.
When launching a process with NSTask, there is no running shell (unless the process itself is a shell…).
If you want to launch e.g.
grep (a classical one used with wild cards…) you have to make the command executed by a shell:
/bin/sh -c grep ...

so the NSTask parameters are
for the launch path and
[NSArray arrayWithObjects:@"-c",@"grep ...",nil];
for the parameters.