setmntent(3)

1GETMNTENT(3)               Linux Programmer's Manual              GETMNTENT(3)
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NAME

6       getmntent,  setmntent,  addmntent,  endmntent, hasmntopt, getmntent_r -
7       get file system descriptor file entry
8

SYNOPSIS

10       #include <stdio.h>
11       #include <mntent.h>
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13       FILE *setmntent(const char *filename, const char *type);
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15       struct mntent *getmntent(FILE *fp);
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17       int addmntent(FILE *fp, const struct mntent *mnt);
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19       int endmntent(FILE *fp);
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21       char *hasmntopt(const struct mntent *mnt, const char *opt);
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23       /* GNU extension */
24       #define _GNU_SOURCE    /* or _SVID_SOURCE or _BSD_SOURCE */
25       #include <mntent.h>
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27       struct mntent *getmntent_r(FILE *fp, struct mntent *mntbuf,
28                                  char *buf, int buflen);
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DESCRIPTION

31       These routines are used to access  the  file  system  description  file
32       /etc/fstab and the mounted file system description file /etc/mtab.
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34       The  setmntent() function opens the file system description file fp and
35       returns a file pointer which can be used by getmntent().  The  argument
36       type is the type of access required and can take the same values as the
37       mode argument of fopen(3).
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39       The getmntent() function reads the  next  line  from  the  file  system
40       description file fp and returns a pointer to a structure containing the
41       broken out fields from a line in the file.  The  pointer  points  to  a
42       static area of memory which is overwritten by subsequent calls to getm‐
43       ntent().
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45       The addmntent() function adds the mntent structure mnt to  the  end  of
46       the open file fp.
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48       The endmntent() function closes the file system description file fp.
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50       The  hasmntopt()  function  scans the mnt_opts field (see below) of the
51       mntent structure mnt for a substring that matches opt.  See  <mntent.h>
52       and mount(8) for valid mount options.
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54       The  reentrant  getmntent_r()  function  is similar to getmntent(), but
55       stores the struct mount in the provided *mntbuf and stores the  strings
56       pointed  to  by the entries in that struct in the provided array buf of
57       size buflen.
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59       The mntent structure is defined in <mntent.h> as follows:
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61              struct mntent {
62                      char    *mnt_fsname;    /* name of mounted file system */
63                      char    *mnt_dir;       /* file system path prefix */
64                      char    *mnt_type;      /* mount type (see mntent.h) */
65                      char    *mnt_opts;      /* mount options (see mntent.h) */
66                      int     mnt_freq;       /* dump frequency in days */
67                      int     mnt_passno;     /* pass number on parallel fsck */
68              };
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70       Since fields in the mtab and fstab files are separated  by  whitespace,
71       octal  escapes  are used to represent the four characters space (\040),
72       tab (\011), newline (\012) and backslash (\134)  in  those  files  when
73       they  occur in one of the four strings in a mntent structure.  The rou‐
74       tines addmntent() and getmntent() will convert from string  representa‐
75       tion to escaped representation and back.
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RETURN VALUE

78       The  getmntent()  and  getmntent_r()  functions return a pointer to the
79       mntent structure or NULL on failure.
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81       The addmntent() function returns 0 on success and 1 on failure.
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83       The endmntent() function always returns 1.
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85       The hasmntopt() function returns the address  of  the  substring  if  a
86       match is found and NULL otherwise.
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FILES

89       /etc/fstab          file system description file
90       /etc/mtab           mounted file system description file
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CONFORMING TO

93       The  non-reentrant  functions  are  from SunOS 4.1.3.  A routine getmn‐
94       tent_r() was introduced in HP-UX 10, but it returns an int.  The proto‐
95       type  shown  above is glibc-only.  LSB deprecates the functions endhos‐
96       tent(), sethostent() and setmntent().
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NOTES

99       System V also has a getmntent() function but the calling sequence  dif‐
100       fers, and the returned structure is different. Under System V /etc/mnt‐
101       tab is used.  4.4BSD and Digital Unix have a  routine  getmntinfo(),  a
102       wrapper around the system call getfsstat().
103