e maximum size of core files created
      -d	the maximum size of a process's data segment
      -e	the maximum scheduling priority (`nice')
      -f	the maximum size of files written by the shell and its children
      -i	the maximum number of pending signals
      -k	the maximum number of kqueues allocated for this process
      -l	the maximum size a process may lock into memory
      -m	the maximum resident set size
      -n	the maximum number of open file descriptors
      -p	the pipe buffer size
      -q	the maximum number of bytes in POSIX message queues
      -r	the maximum real-time scheduling priority
      -s	the maximum stack size
      -t	the maximum amount of cpu time in seconds
      -u	the maximum number of user processes
      -v	the size of virtual memory
      -x	the maximum number of file locks
      -P	the maximum number of pseudoterminals
      -R	the maximum time a real-time process can run before blocking
      -T	the maximum number of threads
    
    Not all options are available on all platforms.
    
    If LIMIT is given, it is the new value of the specified resource; the
    special LIMIT values `soft', `hard', and `unlimited' stand for the
    current soft limit, the current hard limit, and no limit, respectively.
    Otherwise, the current value of the specified resource is printed.  If
    no option is given, then -f is assumed.
    
    Values are in 1024-byte increments, except for -t, which is in seconds;
    -p, which is in increments of 512 bytes; -R, which is in microseconds;
    -b, which is in bytes; and -e, -i, -k, -n, -q, -r, -u, -x, and -P,
    which accept unscaled values.
    
    When in posix mode, values supplied with -c and -f are in 512-byte
    increments.
    
    Exit Status:
    Returns success unless an invalid option is supplied or an error occurs.