NAME

creat — create a new file or rewrite an existing one

SYNOPSIS

[OH] #include <sys/stat.h>
#include <fcntl.h>

int creat(const char *path, mode_t mode);


DESCRIPTION

The creat() function shall behave as if it is implemented as follows:

int creat(const char *path, mode_t mode)
{
    return open(path, O_WRONLY|O_CREAT|O_TRUNC, mode);
}

RETURN VALUE

Refer to open.

ERRORS

Refer to open.

EXAMPLES

Creating a File

The following example creates the file /tmp/file with read and write permissions for the file owner and read permission for group and others. The resulting file descriptor is assigned to the fd variable.

#include <fcntl.h>
...
int fd;
mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
char *pathname = "/tmp/file";
...
fd = creat(pathname, mode);
...

APPLICATION USAGE

In multi-threaded applications, the creat() function can leak file descriptors into child processes. Applications should instead use open() with the O_CLOEXEC and O_CLOFORK flags to avoid the leak.

RATIONALE

The creat() function is redundant. Its services are also provided by the open() function. It has been included primarily for historical purposes since many existing applications depend on it. It is best considered a part of the C binding rather than a function that should be provided in other languages.

FUTURE DIRECTIONS

None.

SEE ALSO

mknod, open

XBD <fcntl.h>, <sys/stat.h>, <sys/types.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

In the SYNOPSIS, the optional include of the <sys/types.h> header is removed.

The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:

• The requirement to include <sys/types.h> has been removed. Although <sys/types.h> was required for conforming implementations of previous POSIX specifications, it was not required for UNIX applications.

Issue 7

SD5-XSH-ERN-186 is applied.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0064 [291] is applied.

Issue 8

Austin Group Defects 411 and 1318 are applied, changing the APPLICATION USAGE section.