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NAME
getmntent, setmntent, addmntent, endmntent, hasmntopt, getmntent_r -
get file system 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 */
#define _GNU_SOURCE /* or _SVID_SOURCE or _BSD_SOURCE */
#include <mntent.h>
struct mntent *getmntent_r(FILE *fp, struct mntent *mntbuf,
char *buf, int buflen);
DESCRIPTION
These routines are used to access the file system description file
/etc/fstab and the mounted file system description file /etc/mtab.
The setmntent() function opens the file system description file fp 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 file system
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 getm
ntent().
The addmntent() function adds the mntent structure mnt to the end of
the open file fp.
The endmntent() function closes the file system 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 file system */
char *mnt_dir; /* file system 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 backslash (\134) in those files when
they occur in one of the four strings in a mntent structure. The rou‐
tines addmntent() and getmntent() will convert from string representa‐
tion to escaped representation and back.
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 file system description file
/etc/mtab mounted file system description file
The non-reentrant functions are from SunOS 4.1.3. A routine getmn
tent_r() was introduced in HP-UX 10, but it returns an int. The proto‐
type shown above is glibc-only. LSB deprecates the functions endhos
tent(), sethostent() and setmntent().
NOTES
System V also has a getmntent() function but the calling sequence dif‐
fers, and the returned structure is different. Under System V
/etc/mnttab is used. 4.4BSD and Digital Unix have a routine getm
ntinfo(), a wrapper around the system call getfsstat().
fopen(3), fstab(5), feature_test_macros(7), mount(8)
2003-11-15 GETMNTENT(3)