ulckpwdf(3c)

1lckpwdf(3C)              Standard C Library Functions              lckpwdf(3C)
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NAME

6       lckpwdf, ulckpwdf - manipulate shadow password database lock file
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SYNOPSIS

9       #include <shadow.h>
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11       int lckpwdf(void);
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14       int ulckpwdf(void);
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DESCRIPTION

18       The  lckpwdf()  and  ulckpwdf() functions enable modification access to
19       the password databases through the lock file. A process first uses lck‐
20       pwdf()  to lock the lock file, thereby gaining exclusive rights to mod‐
21       ify the  /etc/passwd or  /etc/shadow password database.  See  passwd(4)
22       and  shadow(4). Upon completing modifications, a process should release
23       the lock on the lock file using  ulckpwdf().  This  mechanism  prevents
24       simultaneous  modification  of  the  password databases. The lock file,
25       /etc/.pwd.lock, is used to coordinate modification access to the  pass‐
26       word databases /etc/passwd and  /etc/shadow.
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RETURN VALUES

29       If  lckpwdf()  is  successful in locking the file within 15 seconds, it
30       returns 0. If unsuccessful (for  example,   /etc/.pwd.lock  is  already
31       locked), it returns −1.
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34       If  ulckpwdf()  is successful in unlocking the file  /etc/.pwd.lock, it
35       returns 0. If unsuccessful (for  example,   /etc/.pwd.lock  is  already
36       unlocked), it returns −1.
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USAGE

39       These  routines are for internal use only; compatibility is not guaran‐
40       teed.
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FILES

43       /etc/passwd       password database
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46       /etc/shadow       shadow password database
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49       /etc/.pwd.lock    lock file
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ATTRIBUTES

53       See attributes(5) for descriptions of the following attributes:
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58       ┌─────────────────────────────┬─────────────────────────────┐
59       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
60       ├─────────────────────────────┼─────────────────────────────┤
61       │MT-Level                     │MT-Safe                      │
62       └─────────────────────────────┴─────────────────────────────┘
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