# CHMOD

Portability Function: Changes the access mode of a file.

## Module

USE IFPORT

result = CHMOD (name,mode)

name | (Input) Character*(*). Name of the file whose access mode is to be changed. Must have a single path.
mode | (Input) Character*(*). File permission: either Read, Write, or Execute. The mode parameter can be either symbolic or absolute. An absolute mode is specified with an octal number, consisting of any combination of the following permission bits ORed together:
Permission bit | Description | Action
--- | --- | ---
4000 | Set user ID on execution | W*S: Ignored; never true L*X, M*X: Settable
2000 | Set group ID on execution | W*S: Ignored; never true L*X, M*X: Settable
1000 | Sticky bit | W*S: Ignored; never true L*X, M*X: Settable
0400 | Read by owner | W*S: Ignored; always true L*X, M*X: Settable
0200 | Write by owner | Settable
0100 | Execute by owner | W*S: Ignored; based on file name extension L*X, M*X: Settable
0040, 0020, 0010 | Read, Write, Execute by group | W*S: Ignored; assumes owner permissions L*X, M*X: Settable
0004, 0002, 0001 | Read, Write, Execute by others | W*S: Ignored; assumes owner permissions L*X, M*X: Settable

The following regular expression represents a symbolic mode:

    [ugoa]*[+-=] [rwxXst]*

On Windows* systems, "[ugoa]*" is ignored. On Linux* and macOS systems, a combination of the letters "ugoa" control which users' access to the file will be changed:

u | The user who owns the file
g | Other users in the group that owns the file
o | Other users not in the group that owns the file
a | All users

"[+ - =]" indicates the operation to carry out:

+ | Add the permission
- | Remove the permission
= | Absolutely set the permission

"[rwxXst]*" indicates the permission to add, subtract, or set. On Windows systems, only "w" is significant and affects write permission; all other letters are ignored. On Linux and macOS systems, all letters are significant.

## Results

The result type is INTEGER(4). It is zero if the mode was changed successfully; otherwise, an error code. Possible error codes are:

- ENOENT: The specified file was not found.

- EINVAL: The mode argument is invalid.

- EPERM: Permission denied; the file's mode cannot be changed.

## Example

    USE IFPORT
    integer(4) I,Istatus
    I = ACCESS ("DATAFILE.TXT", "w")
    if (i) then
       ISTATUS = CHMOD ("datafile.txt", "[+w]")
    end if
    I = ACCESS ("DATAFILE.TXT","w")
    print *, i

Parent topic: C to D

## See Also

SETFILEACCESSQQ