福建農(nóng)林大學(xué)操作系統(tǒng)實(shí)驗(yàn)報(bào)告二

操作系統(tǒng)》實(shí)驗(yàn)報(bào)告(二)Linux下的編程(綜合性2學(xué)時(shí))1、實(shí)驗(yàn)?zāi)康模?)熟悉Linux的進(jìn)程機(jī)制。2)熟悉LINUX環(huán)境編程。2、實(shí)驗(yàn)內(nèi)容：(1)完成LINUX系統(tǒng)的登錄，啟動(dòng)終端。2)創(chuàng)建一個(gè)新用尸，名為ddl。要求記錄操作步驟或命令丿予列。[31260100lBwiizeshitaiocalhostsuPassword：[root@localhost3126010018wuzeshi]#adduserddl[root@localhost3126010018wuzeshi]#adduserddladduser：user'ddl1alreadyexists切換用尸dd1[root@localhost3126010018wuzeshi]#suddl[ddltaiocalhost3126010018wuzeshi]$|(3)進(jìn)程查看命令PS的使用探討，使用ps命令選項(xiàng)：-l-al，記錄命令的結(jié)果。[ddl@lccalhost3126010018wuzeshi]$ps-I-alFSUIDPIDPPIDCPRINIADDRSZWCHANTTYTIMECMD4S0300128260800-40764waitpts/000:00:00su4SQ30103001G800-27132waitpts/000:00:00bash4SG30973910G809-40369waitpts/000:99:00su4S501309830970800-27098waitpts/000:00:00bash0R501311830980800-27046-pts/000:00:00(4)編寫一個(gè)程序，創(chuàng)建一個(gè)子進(jìn)程，顯示“Newprocess.”子進(jìn)程在休眠(15秒)后，通過(guò)調(diào)用getpid()和getppid()獲取父、子進(jìn)程的id后結(jié)束并退出exit()。父進(jìn)程調(diào)用waitpid()等待子進(jìn)程結(jié)束，并同樣返回其父、子進(jìn)程的id。(提示：運(yùn)行過(guò)程中配合ps-l命令查看進(jìn)程的家族關(guān)系。)

回答問(wèn)題：當(dāng)父進(jìn)程不等待子進(jìn)程的結(jié)束時(shí)，運(yùn)行結(jié)果如何？請(qǐng)分析原因。i_i*new.cK Copytheselection#include<sys/types.h>#include<stdlib.h>#include<stdio.h>main{)intp;whileUp=fork() ；if(p==Ci]printf("NewProcess\n")；sleep(lS)；printf("pid=%d,ppid=%d\n",getpid{},getppid{})exit(Q)；else//^aitpid(0rNULLrS);運(yùn)行結(jié)果： printf("pid=%d.ppid=%d\n"rgetpidUrgetppid()]；C-Tabwidth:8-Ln,IS,Col19 INS03126010018wuzeshi@localhost:/home/3126010018wuzeshi/DesktopFileEditViewSearchJenminal旦巳Ip[roottaiocalhostDesktop]#gccnew2.c-on已w2[root@localhostDesktop]#./new2pid=斗?48.ppid=3641[rootfatocalhostDesktop]#NewProcesspid=斗B49,ppid=1ps-I-alFSUIDPIDPPIDCPRINIADDRSZWCHANTTYTIMECMD4S0363335600800-40763waitpts/909:09:09su斗s0364136330800-27998waitpts/B00:00:00bash斗R04B5636410800-27047-pts/e00:00:00PS原因：父進(jìn)程執(zhí)行到wait的時(shí)次,如果只有一個(gè)wait,其他的子進(jìn)程在父進(jìn)程結(jié)束后會(huì)成為孤兒進(jìn)程init進(jìn)程收養(yǎng)。采用不阻塞方式調(diào)用waitpid的話，父進(jìn)程不會(huì)等待，沒(méi)執(zhí)行完的子進(jìn)程將會(huì)成為孤兒進(jìn)程(5)進(jìn)程的創(chuàng)建：編制一段程序，使用系統(tǒng)調(diào)用fork()創(chuàng)建兩個(gè)子進(jìn)程，在該程序運(yùn)行時(shí)，在系統(tǒng)中就有一個(gè)父進(jìn)程和兩個(gè)子進(jìn)程在活動(dòng)。讓每一個(gè)進(jìn)程在屏幕上顯示一個(gè)字符：父進(jìn)程顯示字符a,子進(jìn)程分別顯示字符b和字符c。試觀察、記錄并分析屏幕上，進(jìn)程運(yùn)行的情況。(提示：運(yùn)行過(guò)程中配合ps-l命令查看進(jìn)程的家族關(guān)系。)圖fork.c諷Mnclud已<stdio.hAmain()intplrp2;while((pl=fork())=-l)；if(pl==0)putcharfb'｝；elsewhile((p2=fork())=-l)；if(pl==0)putchar('c')獲取進(jìn)程及其父進(jìn)程的id.[roattaiocalhostDesktop]#gccfork.c-ofork[root@localhostDesktop]#./fork3[root@localhostDesktop]#ab[root^localhostDesktop]#ps-I[roattaiocalhostDesktop]#gccfork.c-ofork[root@localhostDesktop]#./fork3[root@localhostDesktop]#ab[root^localhostDesktop]#ps-IFSUIDPIDPPIDCPRINIADDRSZWCHANTTYTIMECMD斗S0363335609809-40763waitpts/000:00:00su4s0364136330800-27098waitpts/000:00:00bashR0418536413800-270斗7-pts/e00:00:00［附：系1統(tǒng)調(diào)h用函數(shù)說(shuō)明：1(1)fork()函數(shù)，創(chuàng)建一個(gè)新進(jìn)程。格式：intfork()其中返回int取值意義如下：0：創(chuàng)建子進(jìn)程，從子進(jìn)程返回的id值>0：從父進(jìn)程返回的子進(jìn)程id值-1：創(chuàng)建失敗(2)getpid()與getppid();(3)waitpid(pid,status,options)可用調(diào)用格式：waitpid(O,NULL,O)功能：waitpid()會(huì)暫時(shí)停止目前進(jìn)程的執(zhí)行，直到有信號(hào)來(lái)到或子進(jìn)程結(jié)束。如果在調(diào)用waitpid()時(shí)子進(jìn)程已經(jīng)結(jié)束，則waitpid()會(huì)立即返回子進(jìn)程結(jié)束狀態(tài)值。參數(shù)設(shè)置：pid=0,表示等待進(jìn)程組識(shí)別碼與目前進(jìn)程相同的任何子進(jìn)程；status=NULL，表示忽略進(jìn)程的結(jié)束狀態(tài)；options=0,表示不提供了一些額外的選項(xiàng)來(lái)控制waitpid。(4)相關(guān)的頭文件包含如下：#include<sys/types.h>#include<stdio.h>3