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GETMNTENT(3) Linux Programmer's Manual GETMNTENT(3)
NAME
getmntent, setmntent, addmntent, endmntent, hasmntopt, getmntent_r - get filesystem
descriptor file entry
SYNOPSIS
#include <stdio.h>
#include <mntent.h>
FILE *setmntent(const char *filename, const char *type);
struct mntent *getmntent(FILE *fp);
int addmntent(FILE *fp, const struct mntent *mnt);
int endmntent(FILE *fp);
char *hasmntopt(const struct mntent *mnt, const char *opt);
/* GNU extension */
#include <mntent.h>
struct mntent *getmntent_r(FILE *fp, struct mntent *mntbuf,
char *buf, int buflen);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getmntent_r(): _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
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 from the filesystem description file fp 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 file fp.
The endmntent() function closes the filesystem description file fp.
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 four characters space (\040), tab (\011), newline (\012) and back‐
slash (\134) in those files when they occur in one of the four strings in a mntent struc‐
ture. The routines addmntent() and getmntent() will convert from string representation to
escaped representation and back.
RETURN VALUE
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.
FILES
/etc/fstab filesystem description file
/etc/mtab mounted filesystem description file
CONFORMING TO
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.
NOTES
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().
SEE ALSO
fopen(3), fstab(5), mount(8)
COLOPHON
This page is part of release 3.74 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 http://www.kernel.org/doc/man-pages/.
2009-09-15 GETMNTENT(3)
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