1PWGEN(1) General Commands Manual PWGEN(1)
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6 pwgen - generate pronounceable passwords
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9 pwgen [ OPTION ] [ pw_length ] [ num_pw ]
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12 The pwgen program generates passwords which are designed to be easily
13 memorized by humans, while being as secure as possible. Human-memo‐
14 rable passwords are never going to be as secure as completely com‐
15 pletely random passwords. In particular, passwords generated by pwgen
16 without the -s option should not be used in places where the password
17 could be attacked via an off-line brute-force attack. On the other
18 hand, completely randomly generated passwords have a tendency to be
19 written down, and are subject to being compromised in that fashion.
20 The pwgen program is designed to be used both interactively, and in
22 shell scripts. Hence, its default behavior is differs depending on
23 whether the standard output is a tty device or a pipe to another pro‐
24 gram. Used interactively, pwgen will display a screenful of passwords,
25 allowing the user to pick a single password, and then quickly erase the
26 screen. This prevents someone from being able to "shoulder-surf" the
27 user's chosen password.
28 When standard output is not a tty, pwgen will only generate one pass‐
30 word, as this tends to be much more convenient for shell scripts, and
31 in order to be compatible with previous versions of this program. In
32 addition, for backwards compatibility reasons, pwgen will not use upper
33 case letters or numbers by default in this mode, although this can be
34 overridden using the -n and -c options.
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37 -0, --no-numerals
38 Don't include numbers in the generated passwords.
39 -1 Print the generated passwords one per line.
41 -A, --no-capitalize
43 Don't bother to include any capital letters in the generated
44 passwords.
45 -a, --alt-phonics
47 This option doesn't do anything special; it is present only for
48 backwards compatibility.
49 -B, --ambiguous
51 Don't use characters that could be confused by the user when
52 printed, such as 'l' and '1', or '0' or 'O'. This reduces the
53 number of possible passwords significantly, and as such reduces
54 the quality of the passwords. It may be useful for users who
55 have bad vision, but in general use of this option is not recom‐
56 mended.
57 -c, --capitalize
59 Include at least one capital letter in the password. This is
60 the default if the standard output is a tty device.
61 -C Print the generated passwords in columns. This is the default
63 if the standard output is a tty device.
64 -N, --num-passwords=num
66 Generate num passwords. This defaults to a screenful if pass‐
67 words are printed by columns, and one password.
68 -n, --numerals
70 Include at least one number in the password. This is the
71 default if the standard output is a tty device.
72 -H, --sha1=/path/to/file[#seed]
74 Will use the sha1's hash of given file and the optional seed to
75 create password. It will allow you to compute the same password
76 later, if you remember the file, seed, and pwgen's options used.
77 ie: pwgen -H ~/your_favorite.mp3#your@email.com gives a list of
78 possibles passwords for your pop3 account, and you can ask this
79 list again and again.
80 WARNING: The passwords generated using this option are not very
82 random. If you use this option, make sure the attacker can not
83 obtain a copy of the file. Also, note that the name of the file
84 may be easily available from the ~/.history or ~/.bash_history
85 file.
86 -h, --help
88 Print a help message.
89 -s, --secure
91 Generate completely random, hard-to-memorize passwords. These
92 should only be used for machine passwords, since otherwise it's
93 almost guaranteed that users will simply write the password on a
94 piece of paper taped to the monitor...
95 -y, --symbols
97 Include at least one special character in the password.
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100 This version of pwgen was written by Theodore Ts'o
101 <tytso@alum.mit.edu>. It is modelled after a program originally writ‐
102 ten by Brandon S. Allbery, and then later extensively modified by Olaf
103 Titz, Jim Lynch, and others. It was rewritten from scratch by
104 Theodore Ts'o because the original program was somewhat of a hack, and
105 thus hard to maintain, and because the licensing status of the program
106 was unclear.
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109 passwd(1)
110pwgen version 2.05 January 2006 PWGEN(1)