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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | FILES | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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getmntent(3) Library Functions Manual getmntent(3)
getmntent, setmntent, addmntent, endmntent, hasmntopt, getmntent_r
- get filesystem descriptor file entry
Standard C library (libc, -lc)
#include <stdio.h>
#include <mntent.h>
FILE *setmntent(const char *path, const char *type);
struct mntent *getmntent(FILE *stream);
int addmntent(FILE *restrict stream,
const struct mntent *restrict mnt);
int endmntent(FILE *streamp);
char *hasmntopt(const struct mntent *mnt, const char *opt);
/* GNU extension */
#include <mntent.h>
struct mntent *getmntent_r(int size;
FILE *restrict streamp,
struct mntent *restrict mntbuf,
char buf[restrict size], int size);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
getmntent_r():
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
These routines are used to access the filesystem description file
/etc/fstab and the mounted filesystem description file /etc/mtab.
The setmntent() function opens the filesystem description file
path and returns a file pointer which can be used by getmntent().
The argument type is the type of access required and can take the
same values as the mode argument of fopen(3). The returned stream
should be closed using endmntent() rather than fclose(3).
The getmntent() function reads the next line of the filesystem
description file from stream and returns a pointer to a structure
containing the broken out fields from a line in the file. The
pointer points to a static area of memory which is overwritten by
subsequent calls to getmntent().
The addmntent() function adds the mntent structure mnt to the end
of the open stream.
The endmntent() function closes the stream associated with the
filesystem description file.
The hasmntopt() function scans the mnt_opts field (see below) of
the mntent structure mnt for a substring that matches opt. See
<mntent.h> and mount(8) for valid mount options.
The reentrant getmntent_r() function is similar to getmntent(),
but stores the mntent structure in the provided *mntbuf, and
stores the strings pointed to by the entries in that structure in
the provided array buf of size size.
The mntent structure is defined in <mntent.h> as follows:
struct mntent {
char *mnt_fsname; /* name of mounted filesystem */
char *mnt_dir; /* filesystem path prefix */
char *mnt_type; /* mount type (see mntent.h) */
char *mnt_opts; /* mount options (see mntent.h) */
int mnt_freq; /* dump frequency in days */
int mnt_passno; /* pass number on parallel fsck */
};
Since fields in the mtab and fstab files are separated by
whitespace, octal escapes are used to represent the characters
space (\040), tab (\011), newline (\012), and backslash (\\) in
those files when they occur in one of the four strings in a mntent
structure. The routines addmntent() and getmntent() will convert
from string representation to escaped representation and back.
When converting from escaped representation, the sequence \134 is
also converted to a backslash.
The getmntent() and getmntent_r() functions return a pointer to
the mntent structure or NULL on failure.
The addmntent() function returns 0 on success and 1 on failure.
The endmntent() function always returns 1.
The hasmntopt() function returns the address of the substring if a
match is found and NULL otherwise.
/etc/fstab
filesystem description file
/etc/mtab
mounted filesystem description file
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────┬───────────────┬────────────────────────────────┐
│ Interface │ Attribute │ Value │
├───────────────┼───────────────┼────────────────────────────────┤
│ setmntent(), │ Thread safety │ MT-Safe │
│ endmntent(), │ │ │
│ hasmntopt() │ │ │
├───────────────┼───────────────┼────────────────────────────────┤
│ getmntent() │ Thread safety │ MT-Unsafe race:mntentbuf │
│ │ │ locale │
├───────────────┼───────────────┼────────────────────────────────┤
│ addmntent() │ Thread safety │ MT-Safe race:stream locale │
├───────────────┼───────────────┼────────────────────────────────┤
│ getmntent_r() │ Thread safety │ MT-Safe locale │
└───────────────┴───────────────┴────────────────────────────────┘
None.
The nonreentrant functions are from SunOS 4.1.3. A routine
getmntent_r() was introduced in HP-UX 10, but it returns an int.
The prototype shown above is glibc-only.
System V also has a getmntent() function but the calling sequence
differs, and the returned structure is different. Under System V
/etc/mnttab is used. 4.4BSD and Digital UNIX have a routine
getmntinfo(), a wrapper around the system call getfsstat().
fopen(3), fstab(5), mount(8)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-06-28 getmntent(3)
Pages that refer to this page: getfsent(3), fstab(5)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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