mirror of https://github.com/mkerrisk/man-pages
261 lines
6.1 KiB
Groff
261 lines
6.1 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 21:46:57 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 961109, 031115, aeb
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.\"
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.TH GETMNTENT 3 2019-03-06 "" "Linux Programmer's Manual"
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.SH NAME
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getmntent, setmntent, addmntent, endmntent, hasmntopt,
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getmntent_r \- get filesystem descriptor file entry
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.SH SYNOPSIS
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.nf
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.B #include <stdio.h>
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.B #include <mntent.h>
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.PP
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.BI "FILE *setmntent(const char *" filename ", const char *" type );
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.PP
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.BI "struct mntent *getmntent(FILE *" stream );
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.PP
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.BI "int addmntent(FILE *" stream ", const struct mntent *" mnt );
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.PP
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.BI "int endmntent(FILE *" streamp );
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.PP
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.BI "char *hasmntopt(const struct mntent *" mnt ", const char *" opt );
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/* GNU extension */
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.B #include <mntent.h>
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.PP
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.BI "struct mntent *getmntent_r(FILE *" streamp ", struct mntent *" mntbuf ,
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.BI " char *" buf ", int " buflen );
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.fi
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.PP
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.PP
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.BR getmntent_r ():
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Since glibc 2.19:
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_DEFAULT_SOURCE
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Glibc 2.19 and earlier:
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_BSD_SOURCE || _SVID_SOURCE
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.SH DESCRIPTION
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These routines are used to access the filesystem description file
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.I /etc/fstab
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and the mounted filesystem description file
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.IR /etc/mtab .
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.PP
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The
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.BR setmntent ()
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function opens the filesystem description file
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.I filename
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and returns a file pointer which can be used by
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.BR getmntent ().
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The argument
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.I type
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is the type of access
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required and can take the same values as the
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.I mode
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argument of
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.BR fopen (3).
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The returned stream should be closed using
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.BR endmntent ()
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rather than
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.BR fclose (3).
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.PP
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The
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.BR getmntent ()
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function reads the next line of the filesystem
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description file from
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.I stream
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and returns a pointer to a structure
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containing the broken out fields from a line in the file.
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The pointer
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points to a static area of memory which is overwritten by subsequent
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calls to
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.BR getmntent ().
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.PP
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The
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.BR addmntent ()
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function adds the
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.I mntent
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structure
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.I mnt
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to
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the end of the open
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.IR stream .
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.PP
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The
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.BR endmntent ()
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function closes the
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.IR stream
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associated with the filesystem description file.
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.PP
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The
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.BR hasmntopt ()
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function scans the
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.I mnt_opts
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field (see below)
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of the
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.I mntent
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structure
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.I mnt
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for a substring that matches
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.IR opt .
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See
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.I <mntent.h>
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and
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.BR mount (8)
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for valid mount options.
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.PP
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The reentrant
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.BR getmntent_r ()
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function is similar to
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.BR getmntent (),
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but stores the
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.IR "struct mount"
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in the provided
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.I *mntbuf
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and stores the strings pointed to by the entries in that struct
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in the provided array
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.I buf
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of size
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.IR buflen .
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.PP
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The
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.I mntent
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structure is defined in
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.I <mntent.h>
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as follows:
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.PP
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.in +4n
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.EX
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struct mntent {
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char *mnt_fsname; /* name of mounted filesystem */
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char *mnt_dir; /* filesystem path prefix */
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char *mnt_type; /* mount type (see mntent.h) */
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char *mnt_opts; /* mount options (see mntent.h) */
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int mnt_freq; /* dump frequency in days */
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int mnt_passno; /* pass number on parallel fsck */
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};
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.EE
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.in
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.PP
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Since fields in the mtab and fstab files are separated by whitespace,
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octal escapes are used to represent the characters space (\e040),
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tab (\e011), newline (\e012), and backslash (\e\e) in those files
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when they occur in one of the four strings in a
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.I mntent
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structure.
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The routines
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.BR addmntent ()
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and
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.BR getmntent ()
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will convert
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from string representation to escaped representation and back.
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When converting from escaped representation, the sequence \e134 is
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also converted to a backslash.
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.SH RETURN VALUE
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The
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.BR getmntent ()
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and
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.BR getmntent_r ()
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functions return
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a pointer to the
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.I mntent
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structure or NULL on failure.
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.PP
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The
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.BR addmntent ()
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function returns 0 on success and 1 on failure.
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.PP
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The
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.BR endmntent ()
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function always returns 1.
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.PP
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The
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.BR hasmntopt ()
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function returns the address of the substring if
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a match is found and NULL otherwise.
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.SH FILES
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.TP
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.I /etc/fstab
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filesystem description file
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.TP
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.I /etc/mtab
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mounted filesystem description file
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.ad l
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.TS
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allbox;
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lbw13 lb lbw31
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l l l.
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Interface Attribute Value
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T{
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.BR setmntent (),
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.BR endmntent (),
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.BR hasmntopt ()
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T} Thread safety MT-Safe
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T{
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.BR getmntent ()
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T} Thread safety MT-Unsafe race:mntentbuf locale
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T{
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.BR addmntent ()
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T} Thread safety MT-Safe race:stream locale
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T{
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.BR getmntent_r ()
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T} Thread safety MT-Safe locale
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.TE
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.ad
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.SH CONFORMING TO
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The nonreentrant functions are from SunOS 4.1.3.
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A routine
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.BR getmntent_r ()
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was introduced in HP-UX 10, but it returns an
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.IR int .
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The prototype shown above is glibc-only.
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.SH NOTES
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System V also has a
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.BR getmntent ()
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function but the calling sequence
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differs, and the returned structure is different.
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Under System V
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.I /etc/mnttab
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is used.
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4.4BSD and Digital UNIX have a routine
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.BR getmntinfo (),
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a wrapper around the system call
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.BR getfsstat ().
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.SH SEE ALSO
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.BR fopen (3),
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.BR fstab (5),
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.BR mount (8)
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