Perl select Function

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Description

This function sets the default filehandle for output to FILEHANDLE, setting the filehandle used by functions such as print and write if no filehandle is specified. If FILEHANDLE is not specified, then it returns the name of the current default filehandle.

select (RBITS, WBITS, EBITS, TIMEOUT ) calls the system function select( ) using the bits specified. The select function sets the controls for handling non-blocking I/O requests. Returns the number of filehandles awaiting I/O in scalar context, or the number of waiting filehandles and the time remaining in a list context

Syntax

Following is the simple syntax for this function:

select FILEHANDLE

select

select RBITS, WBITS, EBITS, TIMEOUT

Return Value

TRhis function returns the previous default filehandle if FILEHANDLE specified and Current default filehandle if FILEHANDLE is not specified.

Example

Following is the example code showing its basic usage:

#!/usr/bin/perl -w

open(FILE,">/tmp/t.out");
$oldHandle = select(FILE);
print("This is sent to /tmp/t.out.\n");
select($oldHandle);
print("This is sent to STDOUT.\n");

When above code is executed, it produced following result

This is sent to STDOUT


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