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The file utility performs a series of tests on each file supplied by file and, optionally, on each file listed in ffile in
an attempt to classify it. If the file is not a regular file, its file type is identified. The file types directory, FIFO, block special, and character special are identified
as such. If the file is a regular file and the file is zero-length, it is identified as an empty file.
If file appears to be a text file, file examines the first 512 bytes and tries to determine its programming language. If file
is an executable a.out, file prints the version stamp, provided it is greater than 0. If file is a symbolic link, by default the link is
followed and file tests the file to which the symbolic link refers.
By default, file will try to use the localized magic file /usr/lib/locale/locale/LC_MESSAGES/magic, if it exists, to identify files
that have a magic number. For example, in the Japanese locale, file will try to use /usr/lib/locale/ja/LC_MESSAGES/magic. If a localized magic file does not exist, file will utilize /etc/magic. A magic number is a numeric or string constant that indicates the file type. See magic(4) for an explanation of the format of /etc/magic.
If file does not exist, cannot be read, or its file status could not be determined, it is not considered an error that affects the exit status. The output will indicate
that the file was processed, but that its type could not be determined.
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