Manpage of GETMNTENT

GETMNTENT

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

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 *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  

DESCRIPTION

These routines are used to access the filesystem description file /etc/fstaband the mounted filesystem description file /etc/mtab.

The setmntent() function opens the filesystem description file filenameand returns a file pointer which can be used by getmntent(). The argument typeis the type of access required and can take the same values as the modeargument of fopen(3).

The getmntent() function reads the next line of the filesystem description file from streamand 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 mntentstructure mntto the end of the open stream.

The endmntent() function closes the streamassociated with the filesystem description file.

The hasmntopt() function scans the mnt_optsfield (see below) of the mntentstructure mntfor 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 mountin the provided *mntbufand stores the strings pointed to by the entries in that struct in the provided array bufof size buflen.

The mntentstructure 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 backslash (\134) in those files when they occur in one of the four strings in a mntentstructure. 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 mntentstructure 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
 

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
setmntent(), endmntent(), hasmntopt() Thread safetyMT-Safe
getmntent() Thread safetyMT-Unsafe race:mntentbuf locale
addmntent() Thread safetyMT-Safe race:stream locale
getmntent_r() Thread safetyMT-Safe locale

 

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/mnttabis 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)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
FILES
ATTRIBUTES
CONFORMING TO
NOTES
SEE ALSO

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