그냥 간단히 생각하세요.
 PRI - 우선순위
NI - nice 값
SIZE - 프로세스가 차지하고 있는 메모리
RSS - 프로세스가 차지하고 있는 실제 메모리
SHARE - 프로세스가 쓰고 있는 공유 메모리
STAT - 프로세스의 상태
%CPU, %MEM - 프로세스가 사용하는 CPU, MEM (백분율로)
TIME - 지금까지 CPU를 쓴 시간
COMMAND - 말그대로 명령
 manpage 를 옮겨봅니다.
 from top manpage
 PRI  The priority of the task.
NI   The nice value of the task.  Negative nice values are
     lower priority.
SIZE The  size  of  the  task's  code plus data plus stack
     space, in kilobytes, is shown here.
RSS  The total amount of physical memory used by the task,
     in  kilobytes,  is shown here. For ELF processes used
     library pages are counted here, for  a.out  processes
     not.
SHARE
     The amount of shared memory used by the task is shown
     in this column.
STAT The state of the task is shown  here.  The  state  is
     either S for sleeping, D for uninterruptible sleep, R
     or running, Z for  zombies,  or  T  for  stopped  or
     traced.  These staes are modified by trailing < for a
     process with negative nice value,  N  for  a  process
     with positive nice value, W for a swapped out process
     (this does not work correctly for kernel  processes).
LIB  Size of use library pages. This does not work for ELF
     processes.
%CPU The  task's  share  of  the  CPU  time since the last
     screen update, expressed as a percentage of total CPU
     time per processor.
%MEM The task's share of the physical memory.
TIME Total CPU time the task has used  since  it  started.
     If  cumulative mode is on, this also includes the CPU
     time used by the process's children which have  died.
     You  can  set cumulative mode with the S command line
     option or toggle it with the interactive  command  S.
     The header line will then be changed to CTIME.
COMMAND
     The  task's  command name, which will be truncated if
     it is too long to be displayed on one line.  Tasks in
     memory will have a full command line, but swapped-out
     tasks will only have  the  name  of  the  program  in
     parentheses (for example, "(getty)").
: 쉘에서 top 했을 때
:
:   PID USER     PRI  NI  SIZE  RSS SHARE STAT  LIB %CPU %MEM   TIME COMMAND   
: 26925 nadaun     9   0   900  900   668 R       0  1.9  0.7   0:01 top 
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: 나오는데..
:
: PRI , NI , SIZE, RSS, SHARE, STAT, LIB, CPU, MEM, TIME, COMMAND 등
: 의미좀 알켜주세요..--return true