Isredirected

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IsRedirected

Returns non-zero if standard output, or input if asked, is redirected to a file.

Syntax

Declare Function IsRedirected ( ByVal is_input As Long = 0 ) As Long

Parameters

• is_input

Description

IsRedirected checks whether stdin or stdout is redirected to a file, instead of being connected to the console/terminal as usual.

If is_input is equal to non-zero (-1), IsRedirected checks stdin.
If is_input is equal to zero (0), IsRedirected checks stdout.

Return Value

Returns non-zero (-1) if stdin or stdout is redirected, otherwise returns zero (0).

Remarks

Usage

#include "fbio.bi"

result = IsRedirected( is_input )

Differences from QB

• New to FreeBASIC.

See also

• Reset(Streamno)

Examples

'' A Windows based example, just for the use principle

'' Self-sufficient example, using his own .exe file as dummy input file for stdin redirection

#include "fbio.bi"

'' Quotation marks wrapping for compatibility with spaces in path name

Dim As String pathExe = """" & ExePath & """"

Dim As String fileExe = Mid(Command(0), InStrRev(Command(0), "\") + 1)

Dim As String redirection = " < """ & Command(0)

If LCase(Right(Command(0), 4)) = ".exe" Then

  redirection &= """"

Else

  redirection &= ".exe"""

End If

If Command() = "" Then  '' First process without stdin redirection

  '' Check stdin redirection

  Print "First process without stdin redirection: IsRedirected(-1) = "; IsRedirected(-1)

  '' Creation of asynchronous second process with stdin redirected from file.exe

  Shell("start /d " & pathExe & " /b " & fileExe & redirection & " secondprocess")

  '' Waiting for termination of asynchronous second process

  Sleep

ElseIf Command() = "secondprocess" Then  '' Second process with stdin redirection

  '' Check stdin redirection

  Print "Second process with stdin redirection  : IsRedirected(-1) = "; IsRedirected(-1)

End If

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Category: Operating System Functions
Kind: function

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.