PWGEN(1)PWGEN(1)NAMEpwgen - generate pronounceable passwords
SYNOPSISpwgen [ OPTION ] [ pw_length ] [ num_pw ]
DESCRIPTION
The pwgen program generates passwords which are designed to be easily
memorized by humans, while being as secure as possible. Human-memo‐
rable passwords are never going to be as secure as completely com‐
pletely random passwords. In particular, passwords generated by pwgen
without the -s option should not be used in places where the password
could be attacked via an off-line brute-force attack. On the other
hand, completely randomly generated passwords have a tendency to be
written down, and are subject to being compromised in that fashion.
The pwgen program is designed to be used both interactively, and in
shell scripts. Hence, its default behavior differs depending on
whether the standard output is a tty device or a pipe to another pro‐
gram. Used interactively, pwgen will display a screenful of passwords,
allowing the user to pick a single password, and then quickly erase the
screen. This prevents someone from being able to "shoulder surf" the
user's chosen password.
When standard output (stdout) is not a tty, pwgen will only generate
one password, as this tends to be much more convenient for shell
scripts, and in order to be compatible with previous versions of this
program.
In addition, for backwards compatibility reasons, when stdout is not a
tty and secure password generation mode has not been requested, pwgen
will generate less secure passwords, as if the -0A options had been
passed to it on the command line. This can be overriden using the -nc
options. In the future, the behavior when stdout is a tty may change,
so shell scripts using pwgen should explicitly specify the -nc or -0A
options. The latter is not recommended for security reasons, since
such passwords are far too easy to guess.
OPTIONS-0, --no-numerals
Don't include numbers in the generated passwords.
-1 Print the generated passwords one per line.
-A, --no-capitalize
Don't bother to include any capital letters in the generated
passwords.
-a, --alt-phonics
This option doesn't do anything special; it is present only for
backwards compatibility.
-B, --ambiguous
Don't use characters that could be confused by the user when
printed, such as 'l' and '1', or '0' or 'O'. This reduces the
number of possible passwords significantly, and as such reduces
the quality of the passwords. It may be useful for users who
have bad vision, but in general use of this option is not recom‐
mended.
-c, --capitalize
Include at least one capital letter in the password. This is
the default if the standard output is a tty device.
-C Print the generated passwords in columns. This is the default
if the standard output is a tty device.
-N, --num-passwords=num
Generate num passwords. This defaults to a screenful if pass‐
words are printed by columns, and one password.
-n, --numerals
Include at least one number in the password. This is the
default if the standard output is a tty device.
-H, --sha1=/path/to/file[#seed]
Will use the sha1's hash of given file and the optional seed to
create password. It will allow you to compute the same password
later, if you remember the file, seed, and pwgen's options used.
ie: pwgen-H ~/your_favorite.mp3#your@email.com gives a list of
possibles passwords for your pop3 account, and you can ask this
list again and again.
WARNING: The passwords generated using this option are not very
random. If you use this option, make sure the attacker can not
obtain a copy of the file. Also, note that the name of the file
may be easily available from the ~/.history or ~/.bash_history
file.
-h, --help
Print a help message.
-s, --secure
Generate completely random, hard-to-memorize passwords. These
should only be used for machine passwords, since otherwise it's
almost guaranteed that users will simply write the password on a
piece of paper taped to the monitor...
-v, --no-vowels
Generate random passwords that do not contain vowels or numbers
that might be mistaken for vowels. It provides less secure
passwords to allow system administrators to not have to worry
with random passwords accidentally contain offensive substrings.
-y, --symbols
Include at least one special character in the password.
AUTHOR
This version of pwgen was written by Theodore Ts'o
<tytso@alum.mit.edu>. It is modelled after a program originally writ‐
ten by Brandon S. Allbery, and then later extensively modified by Olaf
Titz, Jim Lynch, and others. It was rewritten from scratch by
Theodore Ts'o because the original program was somewhat of a hack, and
thus hard to maintain, and because the licensing status of the program
was unclear.
SEE ALSOpasswd(1)pwgen version 2.05 January 2006 PWGEN(1)
