LCKPWDF(3C) Standard C Library Functions LCKPWDF(3C)

NAME

lckpwdf, ulckpwdf - manipulate shadow password database lock file

SYNOPSIS

#include <shadow.h>

int lckpwdf(void);


int ulckpwdf(void);

DESCRIPTION

The lckpwdf() and ulckpwdf() functions enable modification access to
the password databases through the lock file. A process first uses
lckpwdf() to lock the lock file, thereby gaining exclusive rights to
modify the /etc/passwd or /etc/shadow password database. See
passwd(5) and shadow(5). Upon completing modifications, a process
should release the lock on the lock file using ulckpwdf(). This
mechanism prevents simultaneous modification of the password
databases. The lock file, /etc/.pwd.lock, is used to coordinate
modification access to the password databases /etc/passwd and
/etc/shadow.

RETURN VALUES

If lckpwdf() is successful in locking the file within 15 seconds, it
returns 0. If unsuccessful (for example, /etc/.pwd.lock is already
locked), it returns -1.


If ulckpwdf() is successful in unlocking the file /etc/.pwd.lock, it
returns 0. If unsuccessful (for example, /etc/.pwd.lock is already
unlocked), it returns -1.

USAGE

These routines are for internal use only; compatibility is not
guaranteed.

FILES

/etc/passwd
password database


/etc/shadow
shadow password database


/etc/.pwd.lock
lock file

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | MT-Safe |
+---------------+-----------------+

SEE ALSO

getpwnam(3C), getspnam(3C), passwd(5), shadow(5), attributes(7)

December 29, 1996 LCKPWDF(3C)