pw_init, pw_edit, pw_prompt, pw_copy, pw_scan, pw_error - utility functions
for interactive passwd file updates
System Utilities Library (libutil, -lutil)
pw_edit(int notsetuid, const char *filename);
pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw);
pw_scan(char *bp, struct passwd *pw, int *flags);
pw_error(const char *name, int err, int eval);
These functions are designed as conveniences for interactive programs
which update the passwd file and do nothing else. They generally handle
errors by printing out a message to the standard error stream and possibly
aborting the process.
The pw_init() function prepares for a passwd update by unlimiting all
resource constraints, disabling core dumps (thus preventing dumping the
contents of the passwd database into a world-readable file), and disabling
The pw_edit() function runs an editor (named by the environment variable
EDITOR, or /usr/bin/vi if EDITOR is not set) on the file filename (or
/etc/ptmp if filename is NULL). If notsetuid is nonzero, pw_edit() will
set the effective user and group ID to the real user and group ID before
running the editor.
The pw_prompt() function asks the user whether he or she wants to re-edit
the password file; if the answer is no, pw_prompt() deletes the lock file
and exits the process.
The pw_copy() function reads a passwd file from ffd and writes it to tfd,
updating the entry corresponding to pw->pw_name with the information in
pw. If old_pw is not NULL, it checks to make sure the old entry is the
same as the one described in old_pw or the process is aborted. If an
entry is not found to match pw, a new entry is appended to the passwd
file only if the real user ID is 0.
The pw_scan() function accepts in bp a passwd entry as it would be represented
in /etc/master.passwd and fills in pw with corresponding values;
string fields in pw will be pointers into bp. Some characters in bp will
be overwritten with 0s in order to terminate the strings pointed to by
pw. If flags is non-null, it should be cleared and the following options
enabled if required:
_PASSWORD_NOWARN Don't print warnings.
_PASSWORD_OLDFMT Parse bp as an old format entry as found in
Upon return it is cleared, and filled in with the following flags:
_PASSWORD_NOUID The uid field of bp is empty.
_PASSWORD_NOGID The gid field of bp is empty.
_PASSWD_NOCHG The change field of bp is empty.
_PASSWD_NOEXP The expire field of bp is empty.
The pw_error() function displays an error message, aborts the current
passwd update, and exits the current process. If err is non-zero, a
warning message beginning with name is printed for the current value of
errno. The process exits with status eval.
The pw_scan() function prints a warning message and returns 0 if the
string in the bp argument is not a valid passwd string. Otherwise,
pw_scan() returns 1.
BSD December 15, 1995 BSD
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