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 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 (stdout) is not a tty, pwgen will only generate
30 one password, as this tends to be much more convenient for shell
31 scripts, and in order to be compatible with previous versions of this
32 program.
33 In addition, for backwards compatibility reasons, when stdout is not a
35 tty and secure password generation mode has not been requested, pwgen
36 will generate less secure passwords, as if the -0A options had been
37 passed to it on the command line. This can be overriden using the -nc
38 options. In the future, the behavior when stdout is a tty may change,
39 so shell scripts using pwgen should explicitly specify the -nc or -0A
40 options. The latter is not recommended for security reasons, since
41 such passwords are far too easy to guess.
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44 -0, --no-numerals
45 Don't include numbers in the generated passwords.
46 -1 Print the generated passwords one per line.
48 -A, --no-capitalize
50 Don't bother to include any capital letters in the generated
51 passwords.
52 -a, --alt-phonics
54 This option doesn't do anything special; it is present only for
55 backwards compatibility.
56 -B, --ambiguous
58 Don't use characters that could be confused by the user when
59 printed, such as 'l' and '1', or '0' or 'O'. This reduces the
60 number of possible passwords significantly, and as such reduces
61 the quality of the passwords. It may be useful for users who
62 have bad vision, but in general use of this option is not recom‐
63 mended.
64 -c, --capitalize
66 Include at least one capital letter in the password. This is
67 the default if the standard output is a tty device.
68 -C Print the generated passwords in columns. This is the default
70 if the standard output is a tty device.
71 -N, --num-passwords=num
73 Generate num passwords. This defaults to a screenful if pass‐
74 words are printed by columns, and one password.
75 -n, --numerals
77 Include at least one number in the password. This is the
78 default if the standard output is a tty device.
79 -H, --sha1=/path/to/file[#seed]
81 Will use the sha1's hash of given file and the optional seed to
82 create password. It will allow you to compute the same password
83 later, if you remember the file, seed, and pwgen's options used.
84 ie: pwgen -H ~/your_favorite.mp3#your@email.com gives a list of
85 possibles passwords for your pop3 account, and you can ask this
86 list again and again.
87 WARNING: The passwords generated using this option are not very
89 random. If you use this option, make sure the attacker can not
90 obtain a copy of the file. Also, note that the name of the file
91 may be easily available from the ~/.history or ~/.bash_history
92 file.
93 -h, --help
95 Print a help message.
96 -s, --secure
98 Generate completely random, hard-to-memorize passwords. These
99 should only be used for machine passwords, since otherwise it's
100 almost guaranteed that users will simply write the password on a
101 piece of paper taped to the monitor...
102 -v, --no-vowels
104 Generate random passwords that do not contain vowels or numbers
105 that might be mistaken for vowels. It provides less secure
106 passwords to allow system administrators to not have to worry
107 with random passwords accidentally contain offensive substrings.
108 -y, --symbols
110 Include at least one special character in the password.
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113 This version of pwgen was written by Theodore Ts'o
114 <tytso@alum.mit.edu>. It is modelled after a program originally writ‐
115 ten by Brandon S. Allbery, and then later extensively modified by Olaf
116 Titz, Jim Lynch, and others. It was rewritten from scratch by
117 Theodore Ts'o because the original program was somewhat of a hack, and
118 thus hard to maintain, and because the licensing status of the program
119 was unclear.
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122 passwd(1)
123pwgen version 2.05 January 2006 PWGEN(1)