mode on systems where the run-time libraries distinguish between
binary and text files. If FILEHANDLE is an expression, the value is
taken as the name of the filehandle. Returns true on success,
-C<undef> on failure.
+otherwise it returns C<undef> and sets C<$!> (errno).
If LAYER is omitted or specified as C<:raw> the filehandle is made
suitable for passing binary data. This includes turning off possible CRLF
=item getc
Returns the next character from the input file attached to FILEHANDLE,
-or the undefined value at end of file, or if there was an error.
-If FILEHANDLE is omitted, reads from STDIN. This is not particularly
-efficient. However, it cannot be used by itself to fetch single
-characters without waiting for the user to hit enter. For that, try
-something more like:
+or the undefined value at end of file, or if there was an error (in
+the latter case C<$!> is set). If FILEHANDLE is omitted, reads from
+STDIN. This is not particularly efficient. However, it cannot be
+used by itself to fetch single characters without waiting for the user
+to hit enter. For that, try something more like:
if ($BSD_STYLE) {
system "stty cbreak </dev/tty >/dev/tty 2>&1";
Attempts to read LENGTH I<characters> of data into variable SCALAR
from the specified FILEHANDLE. Returns the number of characters
-actually read, C<0> at end of file, or undef if there was an error.
-SCALAR will be grown or shrunk to the length actually read. If SCALAR
-needs growing, the new bytes will be zero bytes. An OFFSET may be
-specified to place the read data into some other place in SCALAR than
-the beginning. The call is actually implemented in terms of either
-Perl's or system's fread() call. To get a true read(2) system call,
-see C<sysread>.
+actually read, C<0> at end of file, or undef if there was an error (in
+the latter case C<$!> is also set). SCALAR will be grown or shrunk to
+the length actually read. If SCALAR needs growing, the new bytes will
+be zero bytes. An OFFSET may be specified to place the read data into
+some other place in SCALAR than the beginning. The call is actually
+implemented in terms of either Perl's or system's fread() call. To
+get a true read(2) system call, see C<sysread>.
Note the I<characters>: depending on the status of the filehandle,
either (8-bit) bytes or characters are read. By default all
=item sysread FILEHANDLE,SCALAR,LENGTH
-Attempts to read LENGTH I<characters> of data into variable SCALAR from
-the specified FILEHANDLE, using the system call read(2). It bypasses
-buffered IO, so mixing this with other kinds of reads, C<print>,
-C<write>, C<seek>, C<tell>, or C<eof> can cause confusion because
-stdio usually buffers data. Returns the number of characters actually
-read, C<0> at end of file, or undef if there was an error. SCALAR
-will be grown or shrunk so that the last byte actually read is the
-last byte of the scalar after the read.
+Attempts to read LENGTH I<characters> of data into variable SCALAR
+from the specified FILEHANDLE, using the system call read(2). It
+bypasses buffered IO, so mixing this with other kinds of reads,
+C<print>, C<write>, C<seek>, C<tell>, or C<eof> can cause confusion
+because stdio usually buffers data. Returns the number of characters
+actually read, C<0> at end of file, or undef if there was an error (in
+the latter case C<$!> is also set). SCALAR will be grown or shrunk so
+that the last byte actually read is the last byte of the scalar after
+the read.
Note the I<characters>: depending on the status of the filehandle,
either (8-bit) bytes or characters are read. By default all
mixing this with reads (other than C<sysread())>, C<print>, C<write>,
C<seek>, C<tell>, or C<eof> may cause confusion because stdio usually
buffers data. Returns the number of characters actually written, or
-C<undef> if there was an error. If the LENGTH is greater than the
-available data in the SCALAR after the OFFSET, only as much data as is
-available will be written.
+C<undef> if there was an error (in this case the errno variable C<$!>
+is also set). If the LENGTH is greater than the available data in the
+SCALAR after the OFFSET, only as much data as is available will be
+written.
An OFFSET may be specified to write the data from some part of the
string other than the beginning. A negative OFFSET specifies writing
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