In case of missing platform-specific standard channels, the Tcl standard channels are considered as initialized and then immediatelyĬlosed. Which specifies one of the standard names (stdin, stdout and stderr). (b) when information about any standard channel is requested with a call to Tcl_GetStdChannel, or with a call to Tcl_GetChannel (a) when open channels are listed with Tcl_GetChannelNames (or the file channels script command), or This approach is not available at the script level.Ģ) All uninitialized standard channels are initialized to platform-specific default values: Missing platform-specific standard channels do not matter here. Successfully opened for example, in a Tcl application run as a Windows NT service.)ġ) A single standard channel is initialized when it is explicitly specified in a call to Tcl_SetStdChannel. (A channel is not "available" if it could not be These cases differ in how they handle unavailable platform- specific standard channels. Standard channels are initialized by the Tcl library in three cases: when explicitly requested, when implicitly required before returningĬhannel information, or when implicitly required during registration of a new channel. Additional public APIs toĬonsider are Tcl_RegisterChannel, Tcl_CreateChannel and Tcl_GetChannel. The public API procedures dealing directly with standard channels are Tcl_GetStdChannel and Tcl_SetStdChannel. Tcl generalizes this concept in a cross-platform way and exposes standard channels to the script level. The first is the standard input an application can read from, the other two refer to writableĬhannels, one for regular output and the other for error messages. The term standard channels comes out of the Unix world and refers to the three channels automatically opened by the OS for each new appli-Ĭation. This page explains the initialization and use of standard channels in the Tcl library. Tcl_StandardChannels - How the Tcl library deals with the standard channels Standard Channels(3) Tcl Library Procedures Standard Channels(3) _ NAME
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