NAME
lckpwdf(), ulckpwdf() — control access to the /etc/passwd and /etc/shadow files
SYNOPSIS
#include <shadow.h>
int lckpwdf (void)
int ulckpwdf (void)
DESCRIPTION
The
lckpwdf()
and
ulckpwdf()
routines are used to coordinate modification access to the password file
/etc/passwd
and to the shadow password file
/etc/shadow.
The lock file used by these two routines is
/etc/.pwd.lock.
A process first calls
lckpwdf()
to gain exclusive access rights for modification.
When modifications are complete,
ulckpwdf()
is called to release the lock on
/etc/.pwd.lock.
This mechanism prevents
simultaneous modification of the files.
RETURN VALUE
The
lckpwdf()
routine returns zero upon successful completion.
If the lock could not be obtained, it returns -1 and sets
errno
to indicate the error.
The
ulckpwdf()
routine returns zero upon successful completion.
If the lock has already been released,
ulckpwdf()
returns -1 and sets
errno
to indicate the error.
FILES
/etc/passwd
/etc/shadow
/etc/.pwd.lock
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