140 lines
3.2 KiB
Groff
140 lines
3.2 KiB
Groff
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.TH GETPWENT 3
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.SH NAME
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getpwent, getpwnam, getpwuid, setpwent, endpwent, setpwfile \- password file routines
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.SH SYNOPSIS
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.ft B
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.nf
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#include <pwd.h>
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struct passwd *getpwent(void)
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struct passwd *getpwnam(const char *\fIname\fP)
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struct passwd *getpwuid(uid_t \fIuid\fP)
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int setpwent(void)
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void endpwent(void)
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void setpwfile(const char *\fIfile\fP)
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.fi
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.ft P
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.SH DESCRIPTION
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These functions are used to obtain information from the password file. They
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return this information in a
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.B struct passwd
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as defined by <pwd.h>:
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.PP
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.nf
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.ta +4n +6n +15n
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struct passwd {
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char *pw_name; /* login name */
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char *pw_passwd; /* encrypted password */
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uid_t pw_uid; /* numeric user id */
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gid_t pw_gid; /* numeric group id */
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char *pw_gecos; /* user full name and other info */
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char *pw_dir; /* user's home directory */
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char *pw_shell; /* name of the user's shell */
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};
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.fi
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.PP
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.B Getpwent()
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reads the password file entry by entry.
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.B Getpwnam()
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scans the entire password file for the user with the given
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.IR name .
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.B Getpwuid()
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looks for the first user with the given
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.IR uid .
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The
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.B setpwent()
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and
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.B endpwent()
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functions are used to open and later close the password file. With
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.B setpwfile()
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one can specify the file to read other than the normal password file. This
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only sets the name, the next
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.B setpwent()
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call will open the file. Do not touch the file name while it is active.
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Use
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.B setpwfile(NULL)
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to revert back to the normal password file.
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.PP
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The usual way to scan the password file is (error checking omitted):
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.PP
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.RS
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.nf
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.DT
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setpwent();
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while ((pw = getpwent()) != NULL)
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if (appropriate_test(pw)) break;
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endpwent();
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.fi
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.RE
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.PP
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The
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.B pw
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variable contains the entry that is wanted if non-NULL. The
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.B getpwnam()
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and
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.B getpwuid()
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functions are implemented as in this example, with error checking of course.
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.PP
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.B Getpwent()
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calls
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.B setpwent()
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if this has not yet been done.
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.B Setpwent()
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first calls
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.B endpwent()
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if the password file is still open. (Other implementations may simply
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rewind the file.)
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.SH FILES
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.TP 15
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.B /etc/passwd
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The password file database.
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.SH "SEE ALSO"
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.BR cuserid (3),
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.BR getlogin (3),
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.BR getgrent (3),
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.BR passwd (5).
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.SH DIAGNOSTICS
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.B Setpwent()
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has the same return value and error codes as the
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.BR open (2)
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call it uses to open the password file. The
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.BI get xxx ()
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functions return NULL on end of file, entry not found, or error. You can
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set
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.B errno
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to zero before the call and check it after.
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.SH NOTES
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All
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.BI get xxx ()
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routines return a pointer to static storage that is overwritten in each call.
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.PP
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Only
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.B getpwnam()
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and
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.B getpwuid()
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are defined by \s-2POSIX\s+2. The
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.B _MINIX_SOURCE
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macro must be defined before including <pwd.h> to make the other functions
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visible. The
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.B pw_passwd
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and
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.B pw_gecos
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fields are also not defined by \s-2POSIX\s+2, but are always visible.
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Portable code cannot reliably detect errors by setting
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.B errno
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to zero. Under Minix it is better to make a
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.B getpwent()
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scan if you need to look up several user-id's or names, but portable code
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had better use several
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.B getpwuid()
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or
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.B getpwnam()
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calls. The
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.B getpwent()
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is usually available on other systems, but may be very expensive.
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.SH AUTHOR
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Kees J. Bot (kjb@cs.vu.nl)
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.\"
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.\" $PchId: getpwent.3,v 1.2 1996/04/11 06:37:43 philip Exp $
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