OpenBSD manual page server

Manual Page Search Parameters

UMASK(2) System Calls Manual UMASK(2)

umaskset file creation mode mask

#include <sys/types.h>
#include <sys/stat.h>

umask(mode_t numask);

The () routine sets the process's file mode creation mask to numask and returns the previous value of the mask. Only the read, write, and execute file permission bits of numask are honored, all others are ignored.

The file mode creation mask is used by the bind(2), mkdir(2), mkdirat(2), mkfifo(2), mkfifoat(2), mknod(2), mknodat(2), open(2) and openat(2) system calls to turn off corresponding bits requested in the file mode (see chmod(2)). This clearing allows users to restrict the default access to their files.

The default mask value is S_IWGRP|S_IWOTH (022, write access for the owner only). Child processes inherit the mask of the calling process.

The previous value of the file mode mask is returned by the call.

The umask() function is always successful.

chmod(2), mkdir(2), mkfifo(2), mknod(2), open(2)

The umask() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

The umask() system call first appeared in Version 7 AT&T UNIX.

February 18, 2022 OpenBSD-7.4