---
name: "EnterFile"
section: "3tcl"
platform: "linux"
package: "tcl74-dev"
version: "7.4p3-5"
release: "Debian 1.3 (Bo)"
platforms: ["linux"]
url: "https://new.carta.tech/EnterFile"
---

# EnterFile(3tcl)

manipulate the table of open files

```

```

## NAME

Tcl\_EnterFile, Tcl\_GetOpenFile, Tcl\_FilePermissions - manipulate the table of open files

## SYNOPSIS

```
#include <tcl.h>

Tcl_EnterFile(interp, file, permissions)

int
Tcl_GetOpenFile(interp, string, write, checkUsage, filePtr)

int
Tcl_FilePermissions(file)
```

## ARGUMENTS

- Tcl\_Interp *\*interp* (in)

  Tcl interpreter from which file is to be accessed.

- FILE *\*file* (in)

  Handle for file that is to become accessible in *interp*.

- int *permissions* (in)

  OR-ed combination of TCL\_FILE\_READABLE and TCL\_FILE\_WRITABLE;  indicates whether *file* was opened for reading or writing or both.

- char *\*string* (in)

  String identifying file, such as **stdin** or **file4**.

- int *write* (in)

  Non-zero means the file will be used for writing, zero means it will be used for reading.

- int *checkUsage* (in)

  If non-zero, then an error will be generated if the file wasn't opened for the access indicated by *write*.

- FILE *\*\*filePtr* (out)

  Points to word in which to store pointer to FILE structure for the file given by *string*.

  ```

  ```

## DESCRIPTION

These procedures provide access to Tcl's file naming mechanism. **Tcl\_EnterFile** enters an open file into Tcl's file table so that it can be accessed using Tcl commands like **gets**, **puts**, **seek**, and **close**. It returns in *interp-\>result* an identifier such as **file4** that can be used to refer to the file in subsequent Tcl commands. **Tcl\_EnterFile** is typically used to implement new Tcl commands that open sockets, pipes, or other kinds of files not already supported by the built-in commands.

**Tcl\_GetOpenFile** takes as argument a file identifier of the form returned by the **open** command or **Tcl\_EnterFile** and returns at *\*filePtr* a pointer to the FILE structure for the file. The *write* argument indicates whether the FILE pointer will be used for reading or writing. In some cases, such as a file that connects to a pipeline of subprocesses, different FILE pointers will be returned for reading and writing. **Tcl\_GetOpenFile** normally returns TCL\_OK. If an error occurs in **Tcl\_GetOpenFile** (e.g. *string* didn't make any sense or *checkUsage* was set and the file wasn't opened for the access specified by *write*) then TCL\_ERROR is returned and *interp-\>result* will contain an error message. If *checkUsage* is zero and the file wasn't opened for the access specified by *write*, then the FILE pointer returned at *\*filePtr* may not correspond to *write*.

**Tcl\_FilePermissions** returns an OR-ed combination of the mask bits TCL\_FILE\_READABLE and TCL\_FILE\_WRITABLE; these indicate whether the given file was opened for reading or writing or both. If *file* does not refer to a file in Tcl's file table then -1 is returned.

## KEYWORDS

file table, permissions, pipeline, read, write