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Perl Pocket Reference, 5th Edition
book

Perl Pocket Reference, 5th Edition

by Johan Vromans
July 2011
Intermediate to advanced content levelIntermediate to advanced
104 pages
2h 14m
English
O'Reilly Media, Inc.
Content preview from Perl Pocket Reference, 5th Edition

File Test Operators

These unary operators take one argument, either a filename or a filehandle, and test the associated file to see if something is true about it. If the argument is omitted, they test $_ (except for -t, which tests STDIN). If the special argument _ (underscore) is passed, they use the information from the preceding test or stat call. File test operators can be stacked, e.g., -r -w -x file.

See also the filetest pragma in page 19.

-r -w -x

File is readable/writable/executable by effective uid/gid.

-R -W -X

File is readable/writable/executable by real uid/gid.

-o -O

File is owned by effective/real uid.

-e -z

File exists/has zero size.

-s

File exists and has nonzero size. Returns the size.

-f -d

File is a plain file/a directory.

-l -S -p

File is a symbolic link/a socket/a named pipe (FIFO).

-b -c

File is a block/character special file.

-u -g -k

File has setuid/setgid/sticky bit set.

-t

Filehandle (default STDIN) is opened to a tty.

-T -B

File is a text/nontext (binary) file. These tests return true on an empty file, or a file at EOF when testing a filehandle.

-M -A -C

Returns the modification/access/inode-change time of the file. The value is relative to the time the program started and expressed in fractional days. See also $^T in page 72.

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Publisher Resources

ISBN: 9781449311186Errata Page