umask.3p (3442B)
- '\" et
- .TH UMASK "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
- .\"
- .SH PROLOG
- This manual page is part of the POSIX Programmer's Manual.
- The Linux implementation of this interface may differ (consult
- the corresponding Linux manual page for details of Linux behavior),
- or the interface may not be implemented on Linux.
- .\"
- .SH NAME
- umask
- \(em set and get the file mode creation mask
- .SH SYNOPSIS
- .LP
- .nf
- #include <sys/stat.h>
- .P
- mode_t umask(mode_t \fIcmask\fP);
- .fi
- .SH DESCRIPTION
- The
- \fIumask\fR()
- function shall set the file mode creation mask of the process to
- .IR cmask
- and return the previous value of the mask. Only the file permission
- bits of
- .IR cmask
- (see
- .IR <sys/stat.h> )
- are used; the meaning of the other bits is implementation-defined.
- .P
- The file mode creation mask of the process is used to turn off
- permission bits in the
- .IR mode
- argument supplied during calls to the following functions:
- .IP " *" 4
- \fIopen\fR(),
- \fIopenat\fR(),
- \fIcreat\fR(),
- \fImkdir\fR(),
- \fImkdirat\fR(),
- \fImkfifo\fR(),
- and
- \fImkfifoat\fR()
- .IP " *" 4
- \fImknod\fR(),
- \fImknodat\fR()
- .IP " *" 4
- \fImq_open\fR()
- .IP " *" 4
- \fIsem_open\fR()
- .P
- Bit positions that are set in
- .IR cmask
- are cleared in the mode of the created file.
- .SH "RETURN VALUE"
- The file permission bits in the value returned by
- \fIumask\fR()
- shall be the previous value of the file mode creation mask. The state
- of any other bits in that value is unspecified, except that a
- subsequent call to
- \fIumask\fR()
- with the returned value as
- .IR cmask
- shall leave the state of the mask the same as its state before the
- first call, including any unspecified use of those bits.
- .SH ERRORS
- No errors are defined.
- .LP
- .IR "The following sections are informative."
- .SH EXAMPLES
- None.
- .SH "APPLICATION USAGE"
- None.
- .SH RATIONALE
- Unsigned argument and return types for
- \fIumask\fR()
- were proposed. The return type and the argument were both changed to
- .BR mode_t .
- .P
- Historical implementations have made use of additional bits in
- .IR cmask
- for their implementation-defined purposes. The addition of the text
- that the meaning of other bits of the field is implementation-defined
- permits these implementations to conform to this volume of POSIX.1\(hy2017.
- .SH "FUTURE DIRECTIONS"
- None.
- .SH "SEE ALSO"
- .IR "\fIcreat\fR\^(\|)",
- .IR "\fIexec\fR\^",
- .IR "\fImkdir\fR\^(\|)",
- .IR "\fImkfifo\fR\^(\|)",
- .IR "\fImknod\fR\^(\|)",
- .IR "\fImq_open\fR\^(\|)",
- .IR "\fIopen\fR\^(\|)",
- .IR "\fIsem_open\fR\^(\|)"
- .P
- The Base Definitions volume of POSIX.1\(hy2017,
- .IR "\fB<sys_stat.h>\fP",
- .IR "\fB<sys_types.h>\fP"
- .\"
- .SH COPYRIGHT
- Portions of this text are reprinted and reproduced in electronic form
- from IEEE Std 1003.1-2017, Standard for Information Technology
- -- Portable Operating System Interface (POSIX), The Open Group Base
- Specifications Issue 7, 2018 Edition,
- Copyright (C) 2018 by the Institute of
- Electrical and Electronics Engineers, Inc and The Open Group.
- In the event of any discrepancy between this version and the original IEEE and
- The Open Group Standard, the original IEEE and The Open Group Standard
- is the referee document. The original Standard can be obtained online at
- http://www.opengroup.org/unix/online.html .
- .PP
- Any typographical or formatting errors that appear
- in this page are most likely
- to have been introduced during the conversion of the source files to
- man page format. To report such errors, see
- https://www.kernel.org/doc/man-pages/reporting_bugs.html .