perl - Perl 中如何检查文件是否存在？

Question

我有一个相对路径

   $base_path = "input/myMock.TGZ";

myMock.TGZ 是位于输入文件夹中的文件名。文件名可以更改。但路径始终存储在 $base_path 中。

我需要检查该文件是否存在于 $base_path 中。

Answer 1

使用 -e 文件测试运算符测试给定路径中是​​否存在某些东西。

print "$base_path exists!\n" if -e $base_path;

但是，此测试可能比您预期的更广泛。如果该路径中存在普通文件，上面的代码将生成输出，但它也会针对目录、命名管道、符号链接(symbolic link)或更奇特的可能性触发。 See the documentation了解详情。

鉴于您问题中的 .TGZ 扩展名，您似乎期望一个纯文件而不是替代文件。 -f 文件测试运算符询问路径是否通向普通文件。

print "$base_path is a plain file!\n" if -f $base_path;

perlfunc 文档涵盖了长长的列表 Perl's file-test operators这涵盖了您在实践中会遇到的许多情况。

• -r
  File is readable by effective uid/gid.
• -w
  File is writable by effective uid/gid.
• -x
  File is executable by effective uid/gid.
• -o
  File is owned by effective uid.
• -R
  File is readable by real uid/gid.
• -W
  File is writable by real uid/gid.
• -X
  File is executable by real uid/gid.
• -O
  File is owned by real uid.
• -e
  File exists.
• -z
  File has zero size (is empty).
• -s
  File has nonzero size (returns size in bytes).
• -f
  File is a plain file.
• -d
  File is a directory.
• -l
  File is a symbolic link (false if symlinks aren’t supported by the file system).
• -p
  File is a named pipe (FIFO), or Filehandle is a pipe.
• -S
  File is a socket.
• -b
  File is a block special file.
• -c
  File is a character special file.
• -t
  Filehandle is opened to a tty.
• -u
  File has setuid bit set.
• -g
  File has setgid bit set.
• -k
  File has sticky bit set.
• -T
  File is an ASCII or UTF-8 text file (heuristic guess).
• -B
  File is a “binary” file (opposite of -T).
• -M
  Script start time minus file modification time, in days.
• -A
  Same for access time.
• -C
  Same for inode change time (Unix, may differ for other platforms)