求助：Unity无法使用？

$whatis id
id (1p) - return user identity
id (1) - print real and effective user and group IDs


$whatis fork
fork (2) - create a child process
fork (3p) - create a new process


括号里的Ｐ是什么意思？
多谢！

[root@jfht ~]# man -k kill
kill (1) - terminate a process
kill (1p) - terminate or signal processes
kill (2) - send signal to a process
kill (3p) - send a signal to a process or a group of processes
kill [builtins] (1) - bash built-in commands, see bash(1)
killall (1) - kill processes by name
killchar [curs_termattrs] (3x) - curses environment query routines
killpg (2) - send signal to a process group
killpg (3) - send signal to all members of a process group
killpg (3p) - send a signal to a process group
killwchar [curs_termattrs] (3x) - curses environment query routines
mysql_waitpid (1) - kill process and wait for its termination
mysql_zap (1) - kill processes that match a pattern
pkill [pgrep] (1) - look up or signal processes based on name and other attributes
pthread_kill (3p) - send a signal to a thread
skill (1) - send a signal or report process status
snice [skill] (1) - send a signal or report process status
tgkill (2) - Send signal sig to one specific thread, tgid
tkill (2) - send a signal to a single process
xkill (1x) - kill a client by its X resource
yes (1) - output a string repeatedly until killed






为什么有的括号里会有Ｐ或者Ｘ，
比如(1p), (3p) , (1x)　之类的？