patch 命令的“-Np1”选项有什么作用？

Question

有人给我发了一个补丁并告诉我使用以下命令应用它：

patch -Np1 -i file.patch

出于好奇，我试图找出 -Np1 选项的作用，但补丁手册页对此非常不透明。谁能解释这是做什么的？谢谢。

Answer 1

这是两个标志。 -N 和 -p1。

   -N  or  --forward
      Ignore patches that seem to be reversed  or  already  applied.   See
      also -R.

和

   -pnum  or  --strip=num
      Strip the smallest prefix containing num leading slashes  from  each
      file  name found in the patch file.  A sequence of one or more adja-
      cent slashes is counted as a single slash.  This controls  how  file
      names  found  in  the  patch file are treated, in case you keep your
      files in a different directory than the  person  who  sent  out  the
      patch.  For example, supposing the file name in the patch file was

         /u/howard/src/blurfl/blurfl.c

      setting -p0 gives the entire file name unmodified, -p1 gives

         u/howard/src/blurfl/blurfl.c

      without the leading slash, -p4 gives

         blurfl/blurfl.c

      and  not specifying -p at all just gives you blurfl.c.  Whatever you
      end up with is looked for either in the current  directory,  or  the
      directory specified by the -d option.