命令之 ulimit

help ulimit
ulimit: ulimit [-SHacdefilmnpqrstuvx] [limit]
    Modify shell resource limits.
    
    Provides control over the resources available to the shell and processes
    it creates, on systems that allow such control.
    
    Options:
      -S    use the `soft‘ resource limit
      -H    use the `hard‘ resource limit
      -a    all current limits are reported
      -b    the socket buffer size
      -c    the 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
      -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
    
    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, and -u, which is an unscaled
    number of processes.
    
    Exit Status:
    Returns success unless an invalid option is supplied or an error occurs.