【正文】 tl手冊g an employment tribunal claimEmployment tribunals sort out disagreements between employers and employees.You may need to make a claim to an employment tribunal if: ，主要闡述linux下對文件的操作，詳細(xì)介紹了對文件的存取權(quán)限位，對IPC對象的存取權(quán)限同樣具有很好的借鑒意義。 linux內(nèi)核源代碼情景分析（上），毛德操、胡希明著，浙江大學(xué)出版社，給出了系統(tǒng)V消息隊(duì)列相關(guān)的源代碼分析。對POSIX以及系統(tǒng)V消息隊(duì)列都有闡述，對Linux環(huán)境下的程序開發(fā)有極大的啟發(fā)意義。附錄 3：消息隊(duì)列實(shí)例輸出結(jié)果：current number of bytes on queue is 0number of messages in queue is 0max number of bytes on queue is 16384pid of last msgsnd is 0pid of last msgrcv is 0last msgsnd time is Thu Jan 1 08:00:00 1970last msgrcv time is Thu Jan 1 08:00:00 1970last change time is Sun Dec 29 18:28:20 2002msg uid is 0msg gid is 0//上面剛剛創(chuàng)建一個(gè)新消息隊(duì)列時(shí)的輸出current number of bytes on queue is 1number of messages in queue is 1max number of bytes on queue is 16384pid of last msgsnd is 2510pid of last msgrcv is 0last msgsnd time is Sun Dec 29 18:28:21 2002last msgrcv time is Thu Jan 1 08:00:00 1970last change time is Sun Dec 29 18:28:20 2002msg uid is 0msg gid is 0read from msg queue 1 bytes//實(shí)際讀出的字節(jié)數(shù)current number of bytes on queue is 0number of messages in queue is 0max number of bytes on queue is 16384 //每個(gè)消息隊(duì)列最大容量（字節(jié)數(shù)）pid of last msgsnd is 2510pid of last msgrcv is 2510last msgsnd time is Sun Dec 29 18:28:21 2002last msgrcv time is Sun Dec 29 18:28:22 2002last change time is Sun Dec 29 18:28:20 2002msg uid is 0msg gid is 0current number of bytes on queue is 0number of messages in queue is 0max number of bytes on queue is 16388 //可看出超級用戶可修改消息隊(duì)列最大容量pid of last msgsnd is 2510pid of last msgrcv is 2510 //對操作消息隊(duì)列進(jìn)程的跟蹤last msgsnd time is Sun Dec 29 18:28:21 2002last msgrcv time is Sun Dec 29 18:28:22 2002last change time is Sun Dec 29 18:28:23 2002 //msgctl()調(diào)用對msg_ctime有影響msg uid is 8msg gid is 8參考文獻(xiàn)： /* last receive pid */}。 /* max number of bytes on queue */ __kernel_ipc_pid_t msg_lspid。 /* current number of bytes on queue */ unsigned short msg_qnum。 /* Reuse junk fields for 32 bit */ unsigned long msg_lqbytes。 /* last msgrcv time */ __kernel_time_t msg_ctime。 /* last message in queue,unused */ __kernel_time_t msg_stime。 struct msg *msg_first。}。 struct list_head q_receivers。 /* pid of last msgsnd */ pid_t q_lrpid。 /* number of messages in queue */ unsigned long q_qbytes。 /* last change time */ unsigned long q_cbytes。 /* last msgsnd time */ time_t q_rtime。 附錄 2：結(jié)構(gòu)msg_queue用來描述消息隊(duì)列頭，存在于系統(tǒng)空間：struct msg_queue { struct kern_ipc_perm q_perm。如管道和有名管道； 2. 隨內(nèi)核持續(xù)：IPC一直持續(xù)到內(nèi)核重新自舉或者顯示刪除該對象為止。同樣，消息隊(duì)列可以在幾個(gè)進(jìn)程間復(fù)用，而不管這幾個(gè)進(jìn)程是否具有親緣關(guān)系，這一點(diǎn)與有名管道很相似；但消息隊(duì)列是隨內(nèi)核持續(xù)的，與有名管道（隨進(jìn)程持續(xù)）相比，生命力更強(qiáng)，應(yīng)用空間更大。小結(jié)：消息隊(duì)列與管道以及有名管道相比，具有更大的靈活性，首先，它提供有格式字節(jié)流，有利于減少開發(fā)人員的工作量；其次，消息具有類型，在實(shí)際應(yīng)用中，可作為優(yōu)先級使用。printf(msg gid is %d\n,)。()))。()))。()))。printf(pid of last msgrcv is %d\n,)。//每個(gè)消息隊(duì)列的容量（字節(jié)數(shù)）都有限制MSGMNB，值的大小因系統(tǒng)而異。printf(number of messages in queue is %d\n,)。}printf(\n)。if(reval==1){ printf(get msg info error\n)。//只是為了后面輸出時(shí)間的方便reval=msgctl(msgid,IPC_STAT,amp。}}void msg_stat(int msgid,struct msqid_ds msg_info){int reval。//刪除消息隊(duì)列if(reval==1){ printf(unlink msg queue error\n)。}msg_stat(msgid,msg_ginfo)。if(reval==1){ printf(msg set info error\n)。//此處驗(yàn)證超級用戶可以更改消息隊(duì)列的缺省msg_qbytes//注意這里設(shè)置的值大于缺省值reval=msgctl(msgid,IPC_SET,amp。//just a try=8。//從消息隊(duì)列中讀出消息后，輸出消息隊(duì)列屬性msg_stat(msgid,msg_ginfo)。if(reval==1) printf(read msg error\n)。reval=msgrcv(msgid,amp。}//發(fā)送一個(gè)消息后，輸出消息隊(duì)列屬性msg_stat(msgid,msg_ginfo)。msg_sbuf,sizeof(),sflags)。a39。=10。}//創(chuàng)建一個(gè)消息隊(duì)列后，輸出消息隊(duì)列缺省屬性msg_stat(msgid,msg_ginfo)。if(msgid==1){ printf(msg create error\n)。gflags=IPC_CREAT|IPC_EXCL。a39。char* msgpath=/unix/msgqueue。 }msg_rbuf。struct msgmbuf { int mtype。 char mtext[1]。int reval。