| 1 | .TH GETPWENT 3
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| 2 | .SH NAME
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| 3 | getpwent, getpwnam, getpwuid, setpwent, endpwent, setpwfile \- password file routines
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| 4 | .SH SYNOPSIS
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| 5 | .ft B
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| 6 | .nf
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| 7 | #include <pwd.h>
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| 8 |
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| 9 | struct passwd *getpwent(void)
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| 10 | struct passwd *getpwnam(const char *\fIname\fP)
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| 11 | struct passwd *getpwuid(uid_t \fIuid\fP)
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| 12 | int setpwent(void)
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| 13 | void endpwent(void)
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| 14 | void setpwfile(const char *\fIfile\fP)
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| 15 | .fi
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| 16 | .ft P
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| 17 | .SH DESCRIPTION
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| 18 | These functions are used to obtain information from the password file. They
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| 19 | return this information in a
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| 20 | .B struct passwd
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| 21 | as defined by <pwd.h>:
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| 22 | .PP
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| 23 | .nf
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| 24 | .ta +4n +6n +15n
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| 25 | struct passwd {
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| 26 | char *pw_name; /* login name */
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| 27 | char *pw_passwd; /* encrypted password */
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| 28 | uid_t pw_uid; /* numeric user id */
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| 29 | gid_t pw_gid; /* numeric group id */
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| 30 | char *pw_gecos; /* user full name and other info */
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| 31 | char *pw_dir; /* user's home directory */
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| 32 | char *pw_shell; /* name of the user's shell */
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| 33 | };
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| 34 | .fi
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| 35 | .PP
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| 36 | .B Getpwent()
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| 37 | reads the password file entry by entry.
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| 38 | .B Getpwnam()
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| 39 | scans the entire password file for the user with the given
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| 40 | .IR name .
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| 41 | .B Getpwuid()
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| 42 | looks for the first user with the given
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| 43 | .IR uid .
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| 44 | The
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| 45 | .B setpwent()
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| 46 | and
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| 47 | .B endpwent()
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| 48 | functions are used to open and later close the password file. With
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| 49 | .B setpwfile()
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| 50 | one can specify the file to read other than the normal password file. This
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| 51 | only sets the name, the next
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| 52 | .B setpwent()
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| 53 | call will open the file. Do not touch the file name while it is active.
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| 54 | Use
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| 55 | .B setpwfile(NULL)
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| 56 | to revert back to the normal password file.
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| 57 | .PP
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| 58 | The usual way to scan the password file is (error checking omitted):
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| 59 | .PP
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| 60 | .RS
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| 61 | .nf
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| 62 | .DT
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| 63 | setpwent();
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| 64 | while ((pw = getpwent()) != NULL)
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| 65 | if (appropriate_test(pw)) break;
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| 66 | endpwent();
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| 67 | .fi
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| 68 | .RE
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| 69 | .PP
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| 70 | The
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| 71 | .B pw
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| 72 | variable contains the entry that is wanted if non-NULL. The
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| 73 | .B getpwnam()
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| 74 | and
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| 75 | .B getpwuid()
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| 76 | functions are implemented as in this example, with error checking of course.
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| 77 | .PP
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| 78 | .B Getpwent()
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| 79 | calls
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| 80 | .B setpwent()
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| 81 | if this has not yet been done.
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| 82 | .B Setpwent()
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| 83 | first calls
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| 84 | .B endpwent()
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| 85 | if the password file is still open. (Other implementations may simply
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| 86 | rewind the file.)
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| 87 | .SH FILES
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| 88 | .TP 15
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| 89 | .B /etc/passwd
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| 90 | The password file database.
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| 91 | .SH "SEE ALSO"
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| 92 | .BR cuserid (3),
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| 93 | .BR getlogin (3),
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| 94 | .BR getgrent (3),
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| 95 | .BR passwd (5).
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| 96 | .SH DIAGNOSTICS
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| 97 | .B Setpwent()
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| 98 | has the same return value and error codes as the
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| 99 | .BR open (2)
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| 100 | call it uses to open the password file. The
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| 101 | .BI get xxx ()
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| 102 | functions return NULL on end of file, entry not found, or error. You can
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| 103 | set
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| 104 | .B errno
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| 105 | to zero before the call and check it after.
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| 106 | .SH NOTES
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| 107 | All
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| 108 | .BI get xxx ()
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| 109 | routines return a pointer to static storage that is overwritten in each call.
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| 110 | .PP
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| 111 | Only
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| 112 | .B getpwnam()
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| 113 | and
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| 114 | .B getpwuid()
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| 115 | are defined by \s-2POSIX\s+2. The
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| 116 | .B _MINIX_SOURCE
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| 117 | macro must be defined before including <pwd.h> to make the other functions
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| 118 | visible. The
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| 119 | .B pw_passwd
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| 120 | and
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| 121 | .B pw_gecos
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| 122 | fields are also not defined by \s-2POSIX\s+2, but are always visible.
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| 123 | Portable code cannot reliably detect errors by setting
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| 124 | .B errno
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| 125 | to zero. Under MINIX 3 it is better to make a
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| 126 | .B getpwent()
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| 127 | scan if you need to look up several user-id's or names, but portable code
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| 128 | had better use several
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| 129 | .B getpwuid()
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| 130 | or
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| 131 | .B getpwnam()
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| 132 | calls. The
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| 133 | .B getpwent()
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| 134 | is usually available on other systems, but may be very expensive.
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| 135 | .SH AUTHOR
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| 136 | Kees J. Bot (kjb@cs.vu.nl)
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| 137 |
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| 138 | .\"
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| 139 | .\" $PchId: getpwent.3,v 1.2 1996/04/11 06:37:43 philip Exp $
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