OS第1次实验报告：熟悉使用Linux命令和剖析ps命令

Posted 2020-11-27 kaxment

姓名：危文涛

学号：201821121048

班级：计算1812

一、实验环境介绍

操作系统：Microsoft Windows（版本：18363.657）

平台：Cygwin

用户名：危文涛

 

二、实验内容

• 使用man查询命令使用手册

      

 

• 基本命令使用

       help：

       

 

       ls -al：

       

 

•      剖析ps命令

       运行man ps，将手册内容copy：

PROLOG
       This  manual  page is part of the POSIX Programmer\'s Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.

NAME
       ps — report process status

SYNOPSIS
       ps [−aA] [−defl] [−g grouplist] [−G grouplist]
           [−n namelist] [−o format]... [−p proclist] [−t termlist]
           [−u userlist] [−U userlist]

DESCRIPTION
       The ps utility shall write  information  about  processes,  subject  to
       having  appropriate  privileges to obtain information about those pro‐
       cesses.

       By default, ps shall select all processes with the same effective  user
       ID  as  the  current user and the same controlling terminal as the in‐
       voker.

OPTIONS
       The ps  utility  shall  conform  to  the  Base  Definitions  volume  of
       POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       −a        Write  information  for all processes associated with termi‐
                 nals.  Implementations may omit  session  leaders  from  this
                 list.

       −A        Write information for all processes.

       −d        Write information for all processes, except session leaders.

       −e        Write information for all processes.  (Equivalent to −A.)

       −f        Generate  a  full  listing.  (See  the STDOUT section for the
                 contents of a full listing.)

       −g grouplist
                 Write information for processes  whose  session  leaders  are
                 given  in  grouplist.   The application shall ensure that the
                 grouplist is a single argument in the form of  a  <blank>  or
                 <comma>-separated list.

       −G grouplist
                 Write  information  for processes whose real group ID numbers
                 are given in grouplist.  The application  shall  ensure  that
                 the  grouplist  is a single argument in the form of a <blank>
                 or <comma>-separated list.

       −l        Generate a long listing. (See STDOUT for the  contents  of  a
                 long listing.)

        

 −n namelist
                 Specify  the  name  of an alternative system namelist file in
                 place of the default. The name of the default  file  and  the
                 format of a namelist file are unspecified.

       −o format Write information according to the format specification given
                 in format.  This is fully described in  the  STDOUT  section.
                 Multiple  −o options can be specified; the format specifica‐
                 tion shall be interpreted as the <space>-separated  concate‐
                 nation of all the format option-arguments.

       −p proclist
                 Write  information for processes whose process ID numbers are
                 given in proclist.  The application  shall  ensure  that  the
                 proclist  is  a  single  argument in the form of a <blank> or
                 <comma>-separated list.

       −t termlist
                 Write information for  processes  associated  with  terminals
                 given  in  termlist.   The  application shall ensure that the
                 termlist is a single argument in the form  of  a  <blank>  or
                 <comma>-separated  list.  Terminal identifiers shall be given
                 in an implementation-defined format.  On XSI-conformant sys‐
                 tems,  they  shall be given in one of two forms: the device\'s
                 filename (for example, tty04) or, if  the  device\'s  filename
                 starts with tty, just the identifier following the characters
                 tty (for example, "04").

       −u userlist
                 Write information for processes whose user ID numbers or lo‐
                 gin  names are given in userlist.  The application shall en‐
                 sure that the userlist is a single argument in the form of  a
                 <blank>  or  <comma>-separated list. In the listing, the nu‐
                 merical user ID shall be written  unless  the  −f  option  is
                 used, in which case the login name shall be written.

       −U userlist
                 Write information for processes whose real user ID numbers or
                 login names are given in  userlist.   The  application  shall
                 ensure  that the userlist is a single argument in the form of
                 a <blank> or <comma>-separated list.

•    运行ps -ef：

         

         解释含义:

        -e：将所有信息写入进程；

        -f：生成完整的列表。

       返回结果每个字段的含义：

       UID：用户ID
       PID：进程ID
       PPID：父进程ID
       C：CPU占用资源百分比
       STIME：系统启动时间
       TTY：终端的次要装置号码
       COMMAND：执行的命令

        解释ps aux命令中参数的含义：

 

•    运行ps aux：

         

 

       字段解释：

       a：为终端相关的所有进程写入信息

       u：以用户为主的格式来显示程序状况

       x：显示所有程序，不以终端机来区分 

       PGID：进程组ID

       COMMAND：所执行的指令

四、通过该实验产生新的疑问及解答

主要遇到三个问题：

1、进入cygwin后发现用户名的格式不符合要求，然后参照百度，在cygwin中输入mkpasswd -l > /etc/passwd 生成password文件，再在etc目录下

修改该文件中最后一行的三个用户名并保存，最后在home目录下添加一个用户名的文件夹即可。

2.输入man ps查询手册时显示没有ps的手册目录条，之后在网上下载了一个man的文件解压后添加到share目录下并把原来的man文件夹删除即可。

3.输入ps -ef命令后发现uid最后的一个字母消失，刚开始觉得可能是修改用户名的时候漏了一个字母，但后来发现并未遗漏，多次尝试修改之后没有变化，

个人认为是uid的字符串长度限制导致最后的一个字母被省去。