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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | FILES | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
GETMNTENT(3) Linux Programmer's Manual GETMNTENT(3)
getmntent, setmntent, addmntent, endmntent, hasmntopt, getmntent_r -
get filesystem descriptor file entry
#include <stdio.h>
#include <mntent.h>
FILE *setmntent(const char *filename, const char *type);
struct mntent *getmntent(FILE *stream);
int addmntent(FILE *stream, const struct mntent *mnt);
int endmntent(FILE *streamp);
char *hasmntopt(const struct mntent *mnt, const char *opt);
/* GNU extension */
#include <mntent.h>
struct mntent *getmntent_r(FILE *streamp, struct mntent *mntbuf,
char *buf, int buflen);
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
filename 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 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 struct mount in the provided *mntbuf and stores the
strings pointed to by the entries in that struct in the provided
array buf of size buflen.
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 │
└──────────────┴───────────────┴─────────────────────────────────┘
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 release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2017-03-13 GETMNTENT(3)
Pages that refer to this page: getfsent(3), fstab(5)