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NAME | SYNTAX | DESCRIPTION | DESCRIPTION | DIAGNOSTICS | CAVEATS | FILES | SEE ALSO | COLOPHON |
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SHADOW(3) Library Calls SHADOW(3)
shadow, getspnam - encrypted password file routines
#include <shadow.h>
struct spwd *getspent();
struct spwd *getspnam(char *name);
void setspent();
void endspent();
struct spwd *fgetspent(FILE *fp);
struct spwd *sgetspent(char *cp);
int putspent(struct spwd *p, FILE *fp);
int lckpwdf();
int ulckpwdf();
shadow manipulates the contents of the shadow password file,
/etc/shadow. The structure in the #include file is:
struct spwd {
char *sp_namp; /* user login name */
char *sp_pwdp; /* encrypted password */
long int sp_lstchg; /* last password change */
long int sp_min; /* days until change allowed. */
long int sp_max; /* days before change required */
long int sp_warn; /* days warning for expiration */
long int sp_inact; /* days before account inactive */
long int sp_expire; /* date when account expires */
unsigned long int sp_flag; /* reserved for future use */
}
The meanings of each field are:
• sp_namp - pointer to null-terminated user name
• sp_pwdp - pointer to null-terminated password
• sp_lstchg - days since Jan 1, 1970 password was last changed
• sp_min - days before which password may not be changed
• sp_max - days after which password must be changed
• sp_warn - days before password is to expire that user is
warned of pending password expiration
• sp_inact - days after password expires that account is
considered inactive and disabled
• sp_expire - days since Jan 1, 1970 when account will be
disabled
• sp_flag - reserved for future use
getspent, getspname, fgetspent, and sgetspent each return a
pointer to a struct spwd. getspent returns the next entry from
the file, and fgetspent returns the next entry from the given
stream, which is assumed to be a file of the proper format.
sgetspent returns a pointer to a struct spwd using the provided
string as input. getspnam searches from the current position in
the file for an entry matching name.
setspent and endspent may be used to begin and end, respectively,
access to the shadow password file.
The lckpwdf and ulckpwdf routines should be used to insure
exclusive access to the /etc/shadow file. lckpwdf attempts to
acquire a lock using pw_lock for up to 15 seconds. It continues
by attempting to acquire a second lock using spw_lock for the
remainder of the initial 15 seconds. Should either attempt fail
after a total of 15 seconds, lckpwdf returns -1. When both locks
are acquired 0 is returned.
Routines return NULL if no more entries are available or if an
error occurs during processing. Routines which have int as the
return value return 0 for success and -1 for failure.
These routines may only be used by the superuser as access to the
shadow password file is restricted.
/etc/shadow
Secure user account information.
getpwent(3), shadow(5).
This page is part of the shadow-utils (utilities for managing
accounts and shadow password files) project. Information about
the project can be found at
⟨https://github.com/shadow-maint/shadow⟩. If you have a bug
report for this manual page, send it to
[email protected]. This page was obtained
from the project's upstream Git repository
⟨https://github.com/shadow-maint/shadow⟩ on 2024-06-15. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
shadow-utils 4.14.0 06/15/2024 SHADOW(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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