1079513613qqcom • 2020-12-15 13:35:29

<div class="SetPageTerm-side SetPageTerm-smallSide">
<div class="SetPageTerm-sideContent"><a class="SetPageTerm-wordText"><span class="TermText notranslate lang-en">Some systems automatically delete all user files when a user logs off or a job terminates, unless the user explicitly requests that they be kept; other systems keep all files unless the user explicitly deletes them. Discuss the relative merits of each approach.</span></a></div>
</div>
<div class="SetPageTerm-side SetPageTerm-largeSide">
<div class="SetPageTerm-sideContent"><span class="SetPageTerm-definitionText"><span class="TermText notranslate lang-en">Deleting all files not specifically saved by the user has the advantage of minimizing the file space needed for each user by not saving unwanted or unnecessary files. Saving all files unless specifically deleted is more secure for the user in that it is not possible to lose files inadvertently by forgetting to save them.</span></span></div>
</div> PostVer 0

1079513613qqcom • 2020-12-15 13:35:30

<div class="SetPageTerm-side SetPageTerm-smallSide">
<div class="SetPageTerm-sideContent"><a class="SetPageTerm-wordText"><span class="TermText notranslate lang-en">Some systems automatically delete all user files when a user logs off or a job terminates, unless the user explicitly requests that they be kept; other systems keep all files unless the user explicitly deletes them. Discuss the relative merits of each approach.</span></a></div>
</div>
<div class="SetPageTerm-side SetPageTerm-largeSide">
<div class="SetPageTerm-sideContent"><span class="SetPageTerm-definitionText"><span class="TermText notranslate lang-en">Deleting all files not specifically saved by the user has the advantage of minimizing the file space needed for each user by not saving unwanted or unnecessary files. Saving all files unless specifically deleted is more secure for the user in that it is not possible to lose files inadvertently by forgetting to save them.</span></span></div>
</div> PostVer 0

kagenzaclaudiengmailcom • 2020-12-15 13:37:27

Automatic opening and closing of files relieves the user from the invocation of these functions, and thus makes it more convenient to the user; however, it requires more overhead than the case where explicit opening and closing is required. PostVer 0

chipusilesgmailcom • 2020-12-15 15:10:38

<div class="t m0 xf h5 y51 ff4 fs3 fc1 sc0 ls0 ws0"><span class="ff3">Automatic opening and closing of files relieves the user from</span></div>
<div class="t m0 xf h5 y52 ff3 fs3 fc1 sc0 ls0 ws0">the invocation of these functions, and thus makes it more convenient</div>
<div class="t m0 xf h5 y53 ff3 fs3 fc1 sc0 ls0 ws0">to the user; however, it requires more overhead than the case where</div>
<div class="t m0 xf h5 y54 ff3 fs3 fc1 sc0 ls0 ws0">explicit opening and closing is required.</div> PostVer 0

244766935qqcom • 2020-12-15 15:48:26

<h2>2018329621184 边凯昂</h2>
<a class="SetPageTerm-definitionText" rel="noopener"><span class="TermText notranslate lang-en">Automatic opening and closing of files relieves the user from the invocation of these functions, and thus makes it more convenient to the user; however, it requires more overhead than the case where explicit opening and closing is required.</span></a> PostVer 0

cfeshete97gmailcom • 2020-12-15 20:31:12

Advantage: Easier on the developer. Fewer memory leaks or locking issues

Disadvantage: OS needs to keep track of when to open and close the file. May lead to multiple open/close operations if not smart enough.

The open-file table is used to maintain information about files that are currently open. Should the operating system maintain a separate table for each user or just maintain one table that contains references to files that are being accessed by all users at the current time. PostVer 0

653968106qqcom • 2020-12-15 21:32:10

2018329621008徐天然

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/OD11-1.jpg"><img class="alignnone size-medium wp-image-9174" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/OD11-1-300x55.jpg" alt="" width="300" height="55" /></a> PostVer 0

1730854984qqcom • 2020-12-15 21:52:29

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/比较优缺点.jpg"><img class="alignnone size-medium wp-image-9175" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/比较优缺点-300x84.jpg" alt="" width="300" height="84" /></a> PostVer 0

1720650158qqcom • 2020-12-16 10:54:03

Automatic opening and closing of files relieves the user from the invocation of these functions,and thus makes it more convenient to the user;however,it requires more overhead than the case when explicit opening and closing is required. PostVer 0

454234624qqcom • 2020-12-18 15:41:53

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/Online_Disscussion11.jpg"><img class="alignnone size-medium wp-image-9182" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/Online_Disscussion11-300x42.jpg" alt="" width="300" height="42" /></a> PostVer 0

2470994471qqcom • 2020-12-19 20:46:26

Compared with the traditional file editing way,  the advantage is more efficiently for users， but the disadvantage is that extra operatation will cause extra cost. PostVer 0

hokyeejaufoxmailcom • 2020-12-22 09:04:49

<a class="SetPageTerm-definitionText"><span class="TermText notranslate lang-en">Automatic opening and closing of files relieves the user from the invocation of these functions, and thus makes it more convenient to the user; however, it requires more overhead than the case where explicit opening and closing is required.</span></a> PostVer 0

shatino94163com • 2020-12-22 14:29:50

Advantage: Easier on the developer. Fewer memory leaks or locking issues Disadvantage: OS needs to keep track of when to open and close the file. May lead to multiple open/close operations if not smart enough. The open-file table is used to maintain information about files that are currently open. Should the operating system maintain a separate table for each user or just maintain one table that contains references to files that are being accessed by all users at the current time. PostVer 0

1756894282qqcom • 2020-12-22 14:38:02

Some systems automatically open a file the first time it is referenced and close it when the job terminates. The advantages and disadvantages of this scheme and traditional scheme are discussed, that is, users must open and close the file explicitly. Some systems automatically open the file when it is first referenced and close it when the job terminates. The advantages and disadvantages of this scheme and traditional scheme are discussed, that is, users must open and close files explicitly PostVer 0

804824950qqcom • 2020-12-22 14:59:26

Advantages: Eliminate users from calling these functions
Disadvantages: more overhead than display opening and closing PostVer 0

450766287qqcom • 2020-12-22 15:17:52

Automatic opening and closing of files relieves the user from the invocation of these functions, and thus makes it more convenient to the user; however, it requires more overhead than the case where explicit opening and closing is required. PostVer 0

2031115154qqcom • 2020-12-22 15:35:33

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/9S1N0WSIWK@B5BKH.png"><img class="alignnone size-medium wp-image-9203" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/9S1N0WSIWK@B5BKH-300x20.png" alt="" width="300" height="20" /></a> PostVer 0

997371991qqcom • 2020-12-22 15:38:35

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/CAB16825-DD81-45E3-9B01-9730B6F5A886.jpeg"><img class="alignnone size-medium wp-image-9204" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/12/CAB16825-DD81-45E3-9B01-9730B6F5A886-300x107.jpeg" alt="" width="300" height="107" /></a> PostVer 0

wx287_oz26ft1wt2_isbggtha4lgepaasa • 2020-12-24 15:16:21

Automatic opening and closing of files relieves the user from the invocation of these functions,and thus makes it more convenient to the user;however,it requires more overhead than the case when explicit opening and closing is required. PostVer 0

512858048qqcom • 2020-12-25 16:33:52

On my opinion,  opening and closing of files automaticly makes it more convenient for users to avoid invoking these functions; however, it requires more resources than when it needs to be opened and closed explicitly. PostVer 0

1210775967qqcom • 2020-12-27 18:51:18

Advantage: Automatic file opening and closing eliminates user calls to these functions, making it more user friendly.
Disadvantage: More overhead than opening and closing explicitly PostVer 0

1224532347qqcom • 2021-01-01 14:37:51

Advantages: can automatically complete some operations, save time and effort

Disadvantages: some operations become rigid, unable to achieve flexible operation PostVer 0

1079513613qqcom • 2021-01-04 14:18:22

<pre class="scrollbox" data-reactid="63">an ascii file can be read as a stream while a database file can be read via an
index to a block). Other systems leave such interpretation of a fileu2019s data to the process
and provide no help in accessing the data. The method which is u201cbetteru201d depends on the
needs of the processes on the system, and the demands the users place on the operating
system. If a system runs mostly database applications, it may be more efficient for the
operating system to implement a database-type file and provide operations, rather than
making each program implement the same thing (possibly in different ways). For general
purpose systems it may be better to only implement basic file types to keep the operating
system size smaller and allow maximum freedom to the processes on the system.
11.4 Similarly, some systems support many types of structures for a fileu2019s data, while others
simply support a stream of bytes. What are the advantages and disadvantages?
Answer: (See 10.3)
11.5 What are the advantages and disadvantages of recording the name of the creating pro-
gram with the fileu2019s attributes (as is done in the Macintosh Operating System)?
Answer: By recording the name of the creating program, the operating system is able
to implement features (such as automatic program invocation when the file is accessed)
based on this information. It does add overhead in the operating system and require
space in the file descr iptor, however.
11.6 Could you simulate a multilevel directory structure with a single-level directory structure
in which arbitrarily long names can be used? If your answer is yes, explain how you can
do so, and contrast this scheme with the multilevel directory scheme. If your answer is
no, explain what prevents your simulationu2019s success. How would your answer change if
file names were limited to seven characters?
Answer: If arbitrarily long names can be used then it is possible to simulate a multilevel
directory structure. This can be done, for example, by using the character u201c.u201d to indicate
the end of a subdirectory. Thus, for example, the name jim.pascal.F1 specifies that F1 is a
file in subdirectory pascal which in turn is in the root directory jim.
If file names were limited to seven characters, then the above scheme could not be utilized
and thus, in general, the answer is no. The next best approach in this situation would be
to use a specific file as a symbol table (directory) to map arbitrarily long names (such
as jim.pascal.F1) into shorter arbitrary names (such as XX00743), which are then used for
actual file access.</pre> PostVer 0

1119833189qqcom • 2021-01-05 13:32:35

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2021/01/A03F@QZ8HGU4BVGDS8PDM.png"><img class="alignnone size-medium wp-image-9285" src="http://www.yvsou.com/wp-content/uploads/sites/30/2021/01/A03F@QZ8HGU4BVGDS8PDM-300x34.png" alt="" width="300" height="34" /></a> PostVer 0

1285795916qqcom • 2021-01-05 18:14:05

邱锐鹏 2018329621199

Automatically opening and closing a file is more user friendly than the traditional way; but the overhead will be a burden for the computer. PostVer 0

2736689890qqcom • 2021-01-06 21:20:31

2018329621239-严宇豪
Deleting all files not specifically saved by the user has the advantage of minimizing the file space needed for each user by not saving unwanted or unnecessary files. Saving all files unless specifically deleted is more secure for the user in that it is not possible to lose files inadvertently by forgetting to save them. PostVer 0

1403861656qqcom • 2021-01-06 22:10:50

Automatically opening and closing files makes it more user-friendly by eliminating the need for the user to call these features; But it requires more overhead than explicitly opening and closing PostVer 0

439731491qqcom • 2021-01-07 21:58:31

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2021/01/捕获-5.png"><img class="alignnone size-medium wp-image-9328" src="http://www.yvsou.com/wp-content/uploads/sites/30/2021/01/捕获-5-300x43.png" alt="" width="300" height="43" /></a> PostVer 0

962305148qqcom • 2021-01-07 22:20:39

<h2><strong>2018329621064_邢杰焰</strong></h2>
Advantage: Easier on the developer. Fewer memory leaks or locking issues Disadvantage: OS needs to keep track of when to open and close the file. May lead to multiple open/close operations if not smart enough. The open-file table is used to maintain information about files that are currently open. Should the operating system maintain a separate table for each user or just maintain one table that contains references to files that are being accessed by all users at the current time. PostVer 0