Returns the arctangent of Y/X in the range -PI to PI.
-For the tangent operation, you may use the C<POSIX::tan()>
+For the tangent operation, you may use the C<Math::Trig::tan>
function, or use the familiar relation:
sub tan { sin($_[0]) / cos($_[0]) }
$mode = '0644'; chmod oct($mode), 'foo'; # this is better
$mode = 0644; chmod $mode, 'foo'; # this is best
+You can also import the symbolic C<S_I*> constants from the Fcntl
+module:
+
+ use Fcntl ':mode';
+
+ chmod S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH, @executables;
+ # This is identical to the chmod 0755 of the above example.
+
=item chomp VARIABLE
=item chomp LIST
Returns the cosine of EXPR (expressed in radians). If EXPR is omitted,
takes cosine of C<$_>.
-For the inverse cosine operation, you may use the C<POSIX::acos()>
+For the inverse cosine operation, you may use the C<Math::Trig::acos()>
function, or use this relation:
sub acos { atan2( sqrt(1 - $_[0] * $_[0]), $_[0] ) }
instead a Perl builtin. Also see the C<Time::Local> module
(to convert the second, minutes, hours, ... back to seconds since the
stroke of midnight the 1st of January 1970, the value returned by
-time()), and the strftime(3) and mktime(3) function available via the
+time()), and the strftime(3) and mktime(3) functions available via the
POSIX module. To get somewhat similar but locale dependent date
strings, set up your locale environment variables appropriately
(please see L<perllocale>) and try for example:
POSITION, C<1> to set it to the current position plus POSITION, and
C<2> to set it to EOF plus POSITION (typically negative). For WHENCE
you may use the constants C<SEEK_SET>, C<SEEK_CUR>, and C<SEEK_END>
-(start of the file, current position, end of the file) from any of the
-modules Fcntl, C<IO::Seekable>, or POSIX. Returns C<1> upon success,
-C<0> otherwise.
+(start of the file, current position, end of the file) from the Fcntl
+module. Returns C<1> upon success, C<0> otherwise.
If you want to position file for C<sysread> or C<syswrite>, don't use
C<seek>--buffering makes its effect on the file's system position
Returns the sine of EXPR (expressed in radians). If EXPR is omitted,
returns sine of C<$_>.
-For the inverse sine operation, you may use the C<POSIX::asin>
+For the inverse sine operation, you may use the C<Math::Trig::asin>
function, or use this relation:
sub asin { atan2($_[0], sqrt(1 - $_[0] * $_[0])) }
See L<perllocale>.
If Perl understands "quads" (64-bit integers) (this requires
-either that the platform natively supports quads or that Perl
-has been specifically compiled to support quads), the characters
+either that the platform natively support quads or that Perl
+be specifically compiled to support quads), the characters
d u o x X b i D U O
print "quads\n";
If Perl understands "long doubles" (this requires that the platform
-supports long doubles), the flags
+support long doubles), the flags
e f g E F G
print "$file is executable NFS file\n";
}
-(This works on machines only for which the device number is negative under NFS.)
+(This works on machines only for which the device number is negative
+under NFS.)
Because the mode contains both the file type and its permissions, you
should mask off the file type portion and (s)printf using a C<"%o">
$filename, $sb->size, $sb->mode & 07777,
scalar localtime $sb->mtime;
+You can import symbolic mode constants (C<S_IF*>) and functions
+(C<S_IS*>) from the Fcntl module:
+
+ use Fcntl ':mode';
+
+ $mode = (stat($filename))[2];
+
+ $user_rwx = ($mode & S_IRWXU) >> 6;
+ $group_read = ($mode & S_IRGRP) >> 3;
+ $other_execute = $mode & S_IXOTH;
+
+ printf "Permissions are %04o\n", S_ISMODE($mode), "\n";
+
+ $is_setuid = $mode & S_ISUID;
+ $is_setgid = S_ISDIR($mode);
+
+You could write the last two using the C<-u> and C<-d> operators.
+The commonly available S_IF* constants are
+
+ # Permissions: read, write, execute, for user, group, others.
+
+ S_IRWXU S_IRUSR S_IWUSR S_IXUSR
+ S_IRWXG S_IRGRP S_IWGRP S_IXGRP
+ S_IRWXO S_IROTH S_IWOTH S_IXOTH
+
+ # Setuid/Setgid/Stickiness.
+
+ S_ISUID S_ISGID S_ISVTX S_ISTXT
+
+ # File types. Not necessarily all are available on your system.
+
+ S_IFREG S_IFDIR S_IFLNK S_IFBLK S_ISCHR S_IFIFO S_IFSOCK S_IFWHT S_ENFMT
+
+ # The following are compatibility aliases for S_IRUSR, S_IWUSR, S_IXUSR.
+
+ S_IREAD S_IWRITE S_IEXEC
+
+and the S_IF* functions are
+
+ S_IFMODE($mode) the part of $mode containg the permission bits
+ and the setuid/setgid/sticky bits
+
+ S_IFMT($mode) the part of $mode containing the file type
+ which can be bit-anded with e.g. S_IFREG
+ or with the following functions
+
+ # The operators -f, -d, -l, -b, -c, -p, and -s.
+
+ S_ISREG($mode) S_ISDIR($mode) S_ISLNK($mode)
+ S_ISBLK($mode) S_ISCHR($mode) S_ISFIFO($mode) S_ISSOCK($mode)
+
+ # No direct -X operator counterpart, but for the first one
+ # the -g operator is often equivalent. The ENFMT stands for
+ # record flocking enforcement, a platform-dependent feature.
+
+ S_ISENFMT($mode) S_ISWHT($mode)
+
+See your native chmod(2) and stat(2) documentation for more details
+about the S_* constants.
+
=item study SCALAR
=item study
and C<2> to set it to EOF plus POSITION (typically negative). For
WHENCE, you may also use the constants C<SEEK_SET>, C<SEEK_CUR>, and
C<SEEK_END> (start of the file, current position, end of the file)
-from any of the modules Fcntl, C<IO::Seekable>, or POSIX.
+from the Fcntl module.
Returns the new position, or the undefined value on failure. A position
of zero is returned as the string C<"0 but true">; thus C<sysseek> returns
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