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Programming Perl

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3.2.159 stat

stat FILEHANDLE
stat EXPR

This function returns a 13-element list giving the statistics for a file, either the file opened via FILEHANDLE, or named by EXPR. It's typically used as follows:

($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
    $atime,$mtime,$ctime,$blksize,$blocks)
            = stat $filename;

Not all fields are supported on all filesystem types. Here are the meanings of the fields:

FieldMeaning
devDevice number of filesystem
inoInode number
modeFile mode (type and permissions)
nlinkNumber of (hard) links to the file
uidNumeric user ID of file's owner
gidNumeric group ID of file's owner
rdevThe device identifier (special files only)
sizeTotal size of file, in bytes
atimeLast access time since the epoch
mtimeLast modify time since the epoch
ctimeInode change time (NOT creation time!) since the epoch
blksizePreferred blocksize for file system I/O
blocksActual number of blocks allocated

$dev and $ino, taken together, uniquely identify a file. The $blksize and $blocks are likely defined only on BSD-derived filesystems. The $blocks field (if defined) is reported in 512-byte blocks. Note that $blocks*512 can differ greatly from $size for files containing unallocated blocks, or "holes", which aren't counted in $blocks.

If stat is passed the special filehandle consisting of an underline, no actual stat(2) is done, but the current contents of the stat structure from the last stat or stat-based file test (the -x operators) are returned.

The following example first stats $file to see whether it is executable. If it is, it then pulls the device number out of the existing stat structure and tests it to see whether it looks like a Network File System (NFS). Such filesystems tend to have negative device numbers.

if (-x $file and ($d) = stat(_) and $d < 0) {
    print "$file is executable NFS file\n";
}

Hint: if you need only the size of the file, check out the -s file test operator, which returns the size in bytes directly. There are also file tests that return the ages of files in days.


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