Question

This is giving just the output of ls:

String[] cmd={"bash","-c","ls","-l"}:  
ProcessBuilder pb=new ProcessBuilder(cmd);

Whereas this is giving long listing output properly:

String[] cmd={"bash","-c","ls -l"};

Answer 1

In the first code snippet, the -l option is being passed as an argument to bash, and not to ls. Bash interprets the -l option as specifying that it should behave as a ‘login’ shell.

The argument after -c should include the whole bash script (spaces included) that you want to be executed, so the second code snippet is correct.