Visit The New, Modern Unix Linux Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #263
Difficulty: Easy
Alan Turing played a key role in cracking intercepted coded messages that enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic, and in so doing helped win and end the war.
True or False?
Linux & Unix Commands - Search Man Pages

vipw(8) [freebsd man page]

VIPW(8) 						    BSD System Manager's Manual 						   VIPW(8)

NAME
vipw -- edit the password file SYNOPSIS
vipw [-d directory] DESCRIPTION
The vipw utility edits the password file after setting the appropriate locks, and does any necessary processing after the password file is unlocked. If the password file is already locked for editing by another user, vipw will ask you to try again later. The default editor for vipw is vi(1). When run without options, vipw will work with the password files in /etc. The -d option may be used to specify an alternative directory to work with. The vipw utility performs a number of consistency checks on the password entries, and will not allow a password file with a ``mangled'' entry to be installed. If vipw rejects the new password file, the user is prompted to re-enter the edit session. Once the information has been verified, vipw uses pwd_mkdb(8) to update the user database. This is run in the background, and, at very large sites could take several minutes. Until this update is completed, the password file is unavailable for other updates and the new information is not available to programs. ENVIRONMENT
If the following environment variable exists it will be utilized by vipw: EDITOR The editor specified by the string EDITOR will be invoked instead of the default editor vi(1). This can be used to allow a script to non-interactively modify the password file. PW_SCAN_BIG_IDS See pwd_mkdb(8). SEE ALSO
chpass(1), passwd(1), passwd(5), adduser(8), pw(8), pwd_mkdb(8) HISTORY
The vipw utility appeared in 4.0BSD. BUGS
The mechanism for checking for password file modifications requires that the modification time of the password file changes. This means that in a default configuration where file system timestamps are not calculated with sub-second precision, EDITOR has to run for at least one sec- ond. Non-interactive editor scripts should invoke sleep(1) or equivalent to ensure this happens. BSD
February 14, 2012 BSD

Check Out this Related Man Page

PWD_MKDB(8)						    BSD System Manager's Manual 					       PWD_MKDB(8)

NAME
pwd_mkdb -- generate the password databases SYNOPSIS
pwd_mkdb [-c] [-p | -s] [-d directory] [-u username] file DESCRIPTION
pwd_mkdb creates db(3) style secure and insecure databases for the specified file. These databases are then installed into /etc/spwd.db and /etc/pwd.db, respectively. The file is installed into /etc/master.passwd. The file must be in the correct format (see passwd(5)). It is important to note that the format used in this system is different from the historic Version 7 style format. The options are as follows: -c Check if the password file is in the correct format. Do not change, add, or remove any files. -d directory Operate in a base directory other than the default of /etc. All absolute paths (including file) will be made relative to directory. Any directories specified as a part of file will be stripped off. This option is used to create password databases in directories other than etc; for instance in a chroot(8) jail. -p Create a Version 7 style password file and install it into /etc/passwd. -s Only update the secure version of the database. This is most commonly used in conjunction with the -u flag during a password change. Because the insecure database doesn't contain the password there is no reason to update it if the only change is in the password field. Cannot be used in conjunction with the -p flag. -u username Only update the record for the specified user. Utilities that operate on a single user can use this option to avoid the overhead of rebuilding the entire database. This option must never be used if the line number of the user's record in /etc/master.passwd has changed. file The absolute path to a file in master.passwd format, as described in passwd(5). The two databases differ in that the secure version contains the user's encrypted password and the insecure version has an asterisk ('*'). The databases are used by the C library password routines (see getpwent(3)). pwd_mkdb exits zero on success, non-zero on failure. FILES
/etc/master.passwd current password file /etc/passwd a Version 7 format password file /etc/pwd.db insecure password database file /etc/pwd.db.tmp temporary file /etc/spwd.db secure password database file /etc/spwd.db.tmp temporary file SEE ALSO
chpass(1), passwd(1), db(3), getpwent(3), passwd(5), vipw(8) STANDARDS
Previous versions of the system had a program similar to pwd_mkdb, mkpasswd, which built dbm(3) style databases for the password file but depended on the calling programs to install them. The program was renamed in order that previous users of the program not be surprised by the changes in functionality. BUGS
Because of the necessity for atomic update of the password files, pwd_mkdb uses rename(2) to install them. This, however, requires that the file specified on the command line live on the same file system as the /etc directory. There are the obvious races with multiple people running pwd_mkdb on different password files at the same time. The front-ends to pwd_mkdb, chpass(1), passwd(1), and vipw(8) handle the locking necessary to avoid this problem. BSD
June 6, 1993 BSD

Featured Tech Videos