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更少的實用程式可以緩衝多少？

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更少的實用程式可以緩衝多少？

我很好奇。

您可以less毫無問題地讀取 100 GB 檔案。但是如果你cat將一個 100 GB 的文件放入less，我認為less必須緩衝整個文件，因為文件和 less 之間有一個管道（是 64K 嗎？）。

那麼，有人知道 中的緩衝策略嗎less，它會從頭開始緩衝直到記憶體耗盡嗎？

答案1

的線上說明頁less涵蓋了以下主題：

   -bn or --buffers=n
          Specifies  the  amount of buffer space less will use for each file,
          in units of kilobytes (1024 bytes).  By default 64K of buffer space
          is  used  for  each  file  (unless  the  file is a pipe; see the -B
          option).  The -b option specifies instead that n kilobytes of  buf‐
          fer  space  should be used for each file.  If n is -1, buffer space
          is unlimited; that is, the entire file can be read into memory.

   -B or --auto-buffers
          By default, when data is read from a pipe,  buffers  are  allocated
          automatically  as  needed.   If a large amount of data is read from
          the pipe, this can cause a large amount of memory to be  allocated.
          The  -B  option  disables  this automatic allocation of buffers for
          pipes, so that only 64K (or the amount of space specified by the -b
          option)  is  used  for  the pipe.  Warning: use of -B can result in
          erroneous display, since only the most recently viewed part of  the
          piped data is kept in memory; any earlier data is lost.

線上說明頁暗示，如果不透過 -B 和 -b 選項限制緩衝區，緩衝區最終將成長到與整個輸入一樣大。

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