如何检查 Perl 中是否存在文件？

Question

I have a relative path

   $base_path = "input/myMock.TGZ";

myMock.TGZ is the file name located in input folder. The filename can change. But the path is always stored in $base_path.

I need to check if the file exists in $base_path.

转载于:https://stackoverflow.com/questions/2601027/how-can-i-check-if-a-file-exists-in-perl

Answer 1

Test whether something exists at given path using the -e file-test operator.

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

However, this test is probably broader than you intend. The code above will generate output if a plain file exists at that path, but it will also fire for a directory, a named pipe, a symlink, or a more exotic possibility. See the documentation for details.

Given the extension of .TGZ in your question, it seems that you expect a plain file rather than the alternatives. The -f file-test operator asks whether a path leads to a plain file.

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

The perlfunc documentation covers the long list of Perl's file-test operators that covers many situations you will encounter in practice.

• -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)