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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 ⟨http://pkg-shadow.alioth.debian.org/⟩. If
you have a bug report for this manual page, see
⟨http://pkg-shadow.alioth.debian.org/getinvolved.php⟩. This page was
obtained from the project's upstream Git repository
⟨git://anonscm.debian.org/git/pkg-shadow/shadow.git⟩ on 2017-07-05.
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 man-pages@man7.org
shadow-utils 4.4 07/05/2017 SHADOW(3)