shadow(3)

1SHADOW(3)                        Library Calls                       SHADOW(3)
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NAME

6       shadow, getspnam - encrypted password file routines
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SYNTAX

9       #include <shadow.h>
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11       struct spwd *getspent();
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13       struct spwd *getspnam(char *name);
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15       void setspent();
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17       void endspent();
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19       struct spwd *fgetspent(FILE *fp);
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21       struct spwd *sgetspent(char *cp);
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23       int putspent(struct spwd *p, FILE *fp);
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25       int lckpwdf();
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27       int ulckpwdf();
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DESCRIPTION

30       shadow manipulates the contents of the shadow password file,
31       /etc/shadow. The structure in the #include file is:
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33           struct spwd {
34                 char          *sp_namp; /* user login name */
35                 char          *sp_pwdp; /* encrypted password */
36                 long int      sp_lstchg; /* last password change */
37                 long int      sp_min; /* days until change allowed. */
38                 long int      sp_max; /* days before change required */
39                 long int      sp_warn; /* days warning for expiration */
40                 long int      sp_inact; /* days before account inactive */
41                 long int      sp_expire; /* date when account expires */
42                 unsigned long int  sp_flag; /* reserved for future use */
43           }
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45
46       The meanings of each field are:
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48       •   sp_namp - pointer to null-terminated user name
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50       •   sp_pwdp - pointer to null-terminated password
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52       •   sp_lstchg - days since Jan 1, 1970 password was last changed
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54       •   sp_min - days before which password may not be changed
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56       •   sp_max - days after which password must be changed
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58       •   sp_warn - days before password is to expire that user is warned of
59           pending password expiration
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61       •   sp_inact - days after password expires that account is considered
62           inactive and disabled
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64       •   sp_expire - days since Jan 1, 1970 when account will be disabled
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66       •   sp_flag - reserved for future use
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DESCRIPTION

69       getspent, getspname, fgetspent, and sgetspent each return a pointer to
70       a struct spwd.  getspent returns the next entry from the file, and
71       fgetspent returns the next entry from the given stream, which is
72       assumed to be a file of the proper format.  sgetspent returns a pointer
73       to a struct spwd using the provided string as input.  getspnam searches
74       from the current position in the file for an entry matching name.
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76       setspent and endspent may be used to begin and end, respectively,
77       access to the shadow password file.
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79       The lckpwdf and ulckpwdf routines should be used to insure exclusive
80       access to the /etc/shadow file.  lckpwdf attempts to acquire a lock
81       using pw_lock for up to 15 seconds. It continues by attempting to
82       acquire a second lock using spw_lock for the remainder of the initial
83       15 seconds. Should either attempt fail after a total of 15 seconds,
84       lckpwdf returns -1. When both locks are acquired 0 is returned.
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DIAGNOSTICS

87       Routines return NULL if no more entries are available or if an error
88       occurs during processing. Routines which have int as the return value
89       return 0 for success and -1 for failure.
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CAVEATS

92       These routines may only be used by the superuser as access to the
93       shadow password file is restricted.
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FILES

96       /etc/shadow
97           Secure user account information.
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