man3/getfsent.3

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  25 .\" Inspired by a page written by Walter Harms.
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  27 .TH GETFSENT 3 2017-09-15 "GNU" "Linux Programmer's Manual"
  28 .SH NAME
  29 getfsent, getfsspec, getfsfile, setfsent, endfsent \- handle fstab entries
  30 .SH SYNOPSIS
  31 .B #include <fstab.h>
  32 .PP
  33 .B "void endfsent(void);"
  34 .PP
  35 .B "struct fstab *getfsent(void);"
  36 .PP
  37 .BI "struct fstab *getfsfile(const char *" mount_point );
  38 .PP
  39 .BI "struct fstab *getfsspec(const char *" special_file );
  40 .PP
  41 .B "int setfsent(void);"
  42 .SH DESCRIPTION
  43 These functions read from the file
  44 .IR /etc/fstab .
  45 The
  46 .IR "struct fstab"
  47 is defined by:
  48 .PP
  49 .in +4n
  50 .EX
  51 struct fstab {
  52     char       *fs_spec;       /* block device name */
  53     char       *fs_file;       /* mount point */
  54     char       *fs_vfstype;    /* file-system type */
  55     char       *fs_mntops;     /* mount options */
  56     const char *fs_type;       /* rw/rq/ro/sw/xx option */
  57     int         fs_freq;       /* dump frequency, in days */
  58     int         fs_passno;     /* pass number on parallel dump */
  59 };
  60 .EE
  61 .in
  62 .PP
  63 Here the field
  64 .I fs_type
  65 contains (on a *BSD system)
  66 one of the five strings "rw", "rq", "ro", "sw", "xx"
  67 (read-write, read-write with quota, read-only, swap, ignore).
  68 .PP
  69 The function
  70 .BR setfsent ()
  71 opens the file when required and positions it at the first line.
  72 .PP
  73 The function
  74 .BR getfsent ()
  75 parses the next line from the file.
  76 (After opening it when required.)
  77 .PP
  78 The function
  79 .BR endfsent ()
  80 closes the file when required.
  81 .PP
  82 The function
  83 .BR getfsspec ()
  84 searches the file from the start and returns the first entry found
  85 for which the
  86 .I fs_spec
  87 field matches the
  88 .I special_file
  89 argument.
  90 .PP
  91 The function
  92 .BR getfsfile ()
  93 searches the file from the start and returns the first entry found
  94 for which the
  95 .I fs_file
  96 field matches the
  97 .I mount_point
  98 argument.
  99 .SH RETURN VALUE
 100 Upon success, the functions
 101 .BR getfsent (),
 102 .BR getfsfile (),
 103 and
 104 .BR getfsspec ()
 105 return a pointer to a
 106 .IR "struct fstab" ,
 107 while
 108 .BR setfsent ()
 109 returns 1.
 110 Upon failure or end-of-file, these functions return NULL and 0, respectively.
 111 .\" .SH HISTORY
 112 .\" The
 113 .\" .BR getfsent ()
 114 .\" function appeared in 4.0BSD; the other four functions appeared in 4.3BSD.
 115 .SH ATTRIBUTES
 116 For an explanation of the terms used in this section, see
 117 .BR attributes (7).
 118 .TS
 119 allbox;
 120 lb lb lbw24
 121 l l l.
 122 Interface       Attribute       Value
 123 T{
 124 .BR endfsent (),
 125 .br
 126 .BR setfsent ()
 127 T}      Thread safety   MT-Unsafe race:fsent
 128 T{
 129 .BR getfsent (),
 130 .br
 131 .BR getfsspec (),
 132 .br
 133 .BR getfsfile ()
 134 T}      Thread safety   MT-Unsafe race:fsent locale
 135 .TE
 136 .SH CONFORMING TO
 137 These functions are not in POSIX.1.
 138 Several operating systems have them, for example,
 139 *BSD, SunOS, Digital UNIX, AIX (which also has a
 140 .BR getfstype ()).
 141 HP-UX has functions of the same names,
 142 that however use a
 143 .IR "struct checklist"
 144 instead of a
 145 .IR "struct fstab" ,
 146 and calls these functions obsolete, superseded by
 147 .BR getmntent (3).
 148 .SH NOTES
 149 These functions are not thread-safe.
 150 .PP
 151 Since Linux allows mounting a block special device in several places,
 152 and since several devices can have the same mount point, where the
 153 last device with a given mount point is the interesting one,
 154 while
 155 .BR getfsfile ()
 156 and
 157 .BR getfsspec ()
 158 only return the first occurrence, these two functions are not suitable
 159 for use under Linux.
 160 .SH SEE ALSO
 161 .BR getmntent (3),
 162 .BR fstab (5)