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Programming Perl

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3.2.166 sysread

sysread FILEHANDLE, SCALAR, LENGTH, OFFSET
sysread FILEHANDLE, SCALAR, LENGTH

This function attempts to read LENGTH bytes of data into variable SCALAR from the specified FILEHANDLE using read(2). The function returns the number of bytes actually read, or 0 at EOF. It returns the undefined value on error. SCALAR will be grown or shrunk to the length actually read. The OFFSET, if specified, says where in the string to start putting the bytes, so that you can read into the middle of a string that's being used as a buffer. For an example, see syswrite. You should be prepared to handle the problems (like interrupted system calls) that standard I/O normally handles for you. Also, do not mix calls to read and sysread on the same filehandle unless you are into heavy wizardry (and/or pain).


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