Tcl\_SetErrno(3) Tcl Library Procedures Tcl\_SetErrno(3)

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# [NAME](#NAME)

Tcl\_SetErrno, Tcl\_GetErrno, Tcl\_ErrnoId, Tcl\_ErrnoMsg, Tcl\_WinConvertError - manipulate errno to store and retrieve error codes

# [SYNOPSIS](#SYNOPSIS)

```
#include <tcl.h>

void
Tcl_SetErrno(errorCode)

int
Tcl_GetErrno()

const char *
Tcl_ErrnoId()

const char *
Tcl_ErrnoMsg(errorCode)

void
Tcl_WinConvertError(winErrorCode)
```

# [ARGUMENTS](#ARGUMENTS)

int *errorCode* (in)

A POSIX error code such as **ENOENT**.

DWORD *winErrorCode* (in)

A Windows or Winsock error code such as **ERROR\_FILE\_NOT\_FOUND**.

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```

# [DESCRIPTION](#DESCRIPTION)

**Tcl\_SetErrno** and **Tcl\_GetErrno** provide portable access to the **errno** variable, which is used to record a POSIX error code after system calls and other operations such as **Tcl\_Gets**. These procedures are necessary because global variable accesses cannot be made across module boundaries on some platforms.

**Tcl\_SetErrno** sets the **errno** variable to the value of the *errorCode* argument C procedures that wish to return error information to their callers via **errno** should call **Tcl\_SetErrno** rather than setting **errno** directly.

**Tcl\_GetErrno** returns the current value of **errno**. Procedures wishing to access **errno** should call this procedure instead of accessing **errno** directly.

**Tcl\_ErrnoId** and **Tcl\_ErrnoMsg** return string representations of **errno** values. **Tcl\_ErrnoId** returns a machine-readable textual identifier such as “EACCES” that corresponds to the current value of **errno**. **Tcl\_ErrnoMsg** returns a human-readable string such as “permission denied” that corresponds to the value of its *errorCode* argument. The *errorCode* argument is typically the value returned by **Tcl\_GetErrno**. The strings returned by these functions are statically allocated and the caller must not free or modify them.

**Tcl\_WinConvertError** (Windows only) maps the passed Windows or Winsock error code to a POSIX error and stores it in **errno**.

# [KEYWORDS](#KEYWORDS)

errno, error code, global variables

8.3 Tcl

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Document: Tcl_SetErrno(3) from tcl 9.1.0-r2 (Chainguard OS)
Source: https://downloads.sourceforge.net/project/tcl/Tcl/9.1.0/tcl9.1.0-src.tar.gz