CHAIN

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgChain
• Last revised: 2021-01-08

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Temporarily transfers control to an external program

Syntax

` declare function Chain ( byref program as const string ) as long

`

Usage

` result = Chain( program )

`

Parameters

program

The file name (including file path) of the program (executable) to transfer control to.

Return Value

Returns the external program's exit code if executed successfully, or negative one (-1) otherwise.

Description

Transfers control over to an external program. When the program exits, execution resumes immediately after the call to Chain.

Examples

start GeSHi

#ifdef __FB_LINUX__
    Dim As String program = "./program"
#else
    Dim As String program = "program.exe"
#endif

Print "Running " & program & "..."
If (Chain(program) <> 0) Then
    Print program & " not found!"
End If

end GeSHi

Platform Differences

• Linux requires the program name case matches the real name of the file. Windows and DOS are case insensitive. The program chained may be case sensitive for its command line parameters.
• Path separators in Linux are forward slashes / . Windows uses backward slashes \ but it allows for forward slashes . DOS uses backward \ slashes.
• Exit code is limited to 8 bits in DOS.

Differences from QB

• Common does not allow to keep the values of certain variables when chaining programs with Chain.

See also

• Exec transfer temporarily, with arguments
• Run one-way transfer
• Command pick arguments

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