man pages section 3: Basic Library Functions

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Updated: July 2014
 
 

ulckpwdf(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(4) and shadow(4). 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(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
MT-Level
MT-Safe

See Also

getpwnam(3C), getspnam(3C), passwd(4), shadow(4), attributes(5)